Sync branches 260715-0058

64 files changed, 2143 insertions, 697 deletions

diff --git a/build/conf/compilers/gnu_compiler.conf b/build/conf/compilers/gnu_compiler.conf
index 2b269831069..3382f99a79d 100644
--- a/build/conf/compilers/gnu_compiler.conf
+++ b/build/conf/compilers/gnu_compiler.conf
@@ -178,18 +178,6 @@ elsewhen ($CONSISTENT_DEBUG == "yes") {
     }
     YASM_DEBUG_INFO_DISABLE_CACHE__NO_UID__=--replace=${ARCADIA_BUILD_ROOT}=/-B --replace=${ARCADIA_ROOT}=/-S --replace=$(TOOL_ROOT)=/-T ${env:"YASM_TEST_SUITE=1"}
 }
-elsewhen ($CONSISTENT_DEBUG_LIGHT == "yes") {
-    when ($CLANG == "yes") {
-        CL_DEBUG_INFO_DISABLE_CACHE__NO_UID__=-fdebug-prefix-map=${ARCADIA_BUILD_ROOT}=/-B -Xclang -fdebug-compilation-dir -Xclang /tmp
-    }
-    otherwise {
-        CL_DEBUG_INFO_DISABLE_CACHE__NO_UID__=-fdebug-prefix-map=${ARCADIA_BUILD_ROOT}=/-B
-        when ($ARCH_XTENSA == "yes") {
-            CL_DEBUG_INFO_DISABLE_CACHE__NO_UID__=
-        }
-    }
-    YASM_DEBUG_INFO_DISABLE_CACHE__NO_UID__=--replace=${ARCADIA_BUILD_ROOT}=/-B ${env:"YASM_TEST_SUITE=1"}
-}
 
 when ($OS_LINUX == "yes" || $OS_DARWIN == "yes" || $OS_WINDOWS == "yes") {
     # Some android toolchains using old compilers which didn't support some flags (f.e. -fmacro-prefix-map)
diff --git a/contrib/libs/openssl/.yandex_meta/__init__.py b/contrib/libs/openssl/.yandex_meta/__init__.py
index 912cdd7c01b..03d0dc5a5da 100644
--- a/contrib/libs/openssl/.yandex_meta/__init__.py
+++ b/contrib/libs/openssl/.yandex_meta/__init__.py
@@ -1,16 +1,27 @@
-import os.path as P
+import os
 
-from devtools.yamaker.fileutil import subcopy
+from devtools.yamaker import fileutil
+from devtools.yamaker import pathutil
 from devtools.yamaker.modules import Linkable, Switch
 from devtools.yamaker.project import NixProject
 
 
+def post_build(self):
+    os.remove(f"{self.dstdir}/libssl.map")
+    for hdr in fileutil.files(f"{self.dstdir}/include", rel=False, test=pathutil.is_header):
+        with open(hdr, "rt") as hdr_file:
+            data = hdr_file.read()
+        with open(hdr, "wt") as hdr_file:
+            hdr_file.write("#include <contrib/libs/openssl/redef.h>\n")
+            hdr_file.write(data)
+
+
 def post_install(self):
     def d(s):
         return self.dstdir + "/" + s
 
     # Move asm sources to asm/linux.
-    subcopy(self.dstdir, d("asm/linux"), ["**/*.s"], move=True)
+    fileutil.subcopy(self.dstdir, d("asm/linux"), ["**/*.s"], move=True)
     with self.yamakes["crypto"] as m:
         asm = {s for s in m.SRCS if s.endswith(".s")}
         m.SRCS -= asm
@@ -28,7 +39,7 @@ def post_install(self):
         )
         # Shorten paths.
         m.SRCDIR = []
-        m.SRCS = {P.relpath(s, "crypto") for s in m.SRCS}
+        m.SRCS = {os.path.relpath(s, "crypto") for s in m.SRCS}
         m.SRCS -= {"dso/dso_dlfcn.c", "rand/rand_vms.c"}
 
     # Add suppression for ubsan, see also https://github.com/openssl/openssl/issues/22896
@@ -137,6 +148,7 @@ openssl = NixProject(
         "include/openssl/opensslconf.h",
     ],
     keep_paths=[
+        # This asm files were generated manually
         "asm/aarch64/",
         "asm/android/",
         "asm/darwin/",
@@ -144,9 +156,13 @@ openssl = NixProject(
         "asm/ios/",
         "asm/ppc64le/",
         "asm/windows/",
-        "openssl.package.json",
+        # This code is written by us
+        "ar.pyplugin",
         "sanitizers.h",
         "crypto/ubsan.supp",
+        "redef.h",
+        "system_openssl.ya.inc",
     ],
+    post_build=post_build,
     post_install=post_install,
 )
diff --git a/contrib/libs/openssl/apps/progs-linux.h b/contrib/libs/openssl/apps/progs-linux.h
index 2fce5cbc797..b7c2e31b284 100644
--- a/contrib/libs/openssl/apps/progs-linux.h
+++ b/contrib/libs/openssl/apps/progs-linux.h
@@ -2,7 +2,7 @@
  * WARNING: do not edit!
  * Generated by apps/progs.pl
  *
- * Copyright 1995-2023 The OpenSSL Project Authors. All Rights Reserved.
+ * Copyright 1995-2026 The OpenSSL Project Authors. All Rights Reserved.
  *
  * Licensed under the OpenSSL license (the "License").  You may not use
  * this file except in compliance with the License.  You can obtain a copy
diff --git a/contrib/libs/openssl/include/crypto/bn_conf.h b/contrib/libs/openssl/include/crypto/bn_conf.h
index eb25b5c6636..7b4d0a3b106 100644
--- a/contrib/libs/openssl/include/crypto/bn_conf.h
+++ b/contrib/libs/openssl/include/crypto/bn_conf.h
@@ -1,7 +1,8 @@
-#include <contrib/libs/openssl/redef.h>
 #pragma once
 
-#if defined(__ANDROID__) && defined(__arm__)
+#if defined(__wasm__) && !defined(__wasm64__)
+#   include "bn_conf-wasm32.h"
+#elif defined(__ANDROID__) && defined(__arm__)
 #   include "bn_conf-android-arm.h"
 #elif defined(__ANDROID__) && defined(__aarch64__)
 #   include "bn_conf-android-arm64.h"
@@ -21,8 +22,6 @@
 #   include "bn_conf-linux-arm.h"
 #elif defined(__linux__) && (defined(__aarch64__) || defined(_M_ARM64))
 #   include "bn_conf-linux-aarch64.h"
-#elif defined(__wasm__) && !defined(__wasm64__)
-#   include "bn_conf-wasm32.h"
 #else
 #   include "bn_conf-linux.h"
 #endif
diff --git a/contrib/libs/openssl/include/crypto/dso_conf.h b/contrib/libs/openssl/include/crypto/dso_conf.h
index fd60cdfe832..39695b0aaa8 100644
--- a/contrib/libs/openssl/include/crypto/dso_conf.h
+++ b/contrib/libs/openssl/include/crypto/dso_conf.h
@@ -1,4 +1,3 @@
-#include <contrib/libs/openssl/redef.h>
 #pragma once
 
 #if defined(__ANDROID__)
diff --git a/contrib/libs/openssl/include/openssl/opensslconf-freebsd.h b/contrib/libs/openssl/include/openssl/opensslconf-freebsd-x86_64.h
index bdeb5b9a471..bdeb5b9a471 100644
--- a/contrib/libs/openssl/include/openssl/opensslconf-freebsd.h
+++ b/contrib/libs/openssl/include/openssl/opensslconf-freebsd-x86_64.h
diff --git a/contrib/libs/openssl/include/openssl/opensslconf.h b/contrib/libs/openssl/include/openssl/opensslconf.h
index 38164e3cb65..d7f65c6ab1e 100644
--- a/contrib/libs/openssl/include/openssl/opensslconf.h
+++ b/contrib/libs/openssl/include/openssl/opensslconf.h
@@ -1,7 +1,10 @@
-#include <contrib/libs/openssl/redef.h>
 #pragma once
 
-#if defined(__ANDROID__) && defined(__arm__)
+#if defined(__wasm__) && !defined(__wasm64__)
+#   include "opensslconf-wasm32.h"
+#elif defined(__wasm64__)
+#   include "opensslconf-wasm64.h"
+#elif defined(__ANDROID__) && defined(__arm__)
 #   include "opensslconf-android-arm.h"
 #elif defined(__ANDROID__) && defined(__aarch64__)
 #   include "opensslconf-android-arm64.h"
@@ -21,16 +24,12 @@
 #   include "opensslconf-win-x86_64.h"
 #elif defined(_MSC_VER) && (defined(__i686__) || defined(_M_IX86))
 #   include "opensslconf-win-i686.h"
+#elif defined(__FreeBSD__) && (defined(__x86_64__) || defined(_M_X64))
+#   include "opensslconf-freebsd-x86_64.h"
 #elif defined(__linux__) && defined(__arm__)
 #   include "opensslconf-linux-arm.h"
 #elif defined(__linux__) && (defined(__aarch64__) || defined(_M_ARM64))
 #   include "opensslconf-linux-aarch64.h"
-#elif defined(__wasm__) && !defined(__wasm64__)
-#   include "opensslconf-wasm32.h"
-#elif defined(__wasm64__)
-#   include "opensslconf-wasm64.h"
-#elif defined(__FreeBSD__)
-#   include "opensslconf-freebsd.h"
 #else
 #   include "opensslconf-linux.h"
 #endif
diff --git a/contrib/libs/openssl/libssl.map b/contrib/libs/openssl/libssl.map
deleted file mode 100644
index 153358459d1..00000000000
--- a/contrib/libs/openssl/libssl.map
+++ /dev/null
@@ -1,543 +0,0 @@
-OPENSSL_1_1_0 {
-    global:
-        BIO_f_ssl;
-        BIO_new_buffer_ssl_connect;
-        BIO_new_ssl;
-        BIO_new_ssl_connect;
-        BIO_ssl_copy_session_id;
-        BIO_ssl_shutdown;
-        DTLS_client_method;
-        DTLS_method;
-        DTLS_server_method;
-        DTLSv1_2_client_method;
-        DTLSv1_2_method;
-        DTLSv1_2_server_method;
-        DTLSv1_client_method;
-        DTLSv1_listen;
-        DTLSv1_method;
-        DTLSv1_server_method;
-        ERR_load_SSL_strings;
-        OPENSSL_init_ssl;
-        PEM_read_SSL_SESSION;
-        PEM_read_bio_SSL_SESSION;
-        PEM_write_SSL_SESSION;
-        PEM_write_bio_SSL_SESSION;
-        SRP_Calc_A_param;
-        SSL_CIPHER_description;
-        SSL_CIPHER_find;
-        SSL_CIPHER_get_auth_nid;
-        SSL_CIPHER_get_bits;
-        SSL_CIPHER_get_cipher_nid;
-        SSL_CIPHER_get_digest_nid;
-        SSL_CIPHER_get_id;
-        SSL_CIPHER_get_kx_nid;
-        SSL_CIPHER_get_name;
-        SSL_CIPHER_get_version;
-        SSL_CIPHER_is_aead;
-        SSL_CIPHER_standard_name;
-        SSL_COMP_add_compression_method;
-        SSL_COMP_get_compression_methods;
-        SSL_COMP_get_name;
-        SSL_COMP_set0_compression_methods;
-        SSL_CONF_CTX_clear_flags;
-        SSL_CONF_CTX_finish;
-        SSL_CONF_CTX_free;
-        SSL_CONF_CTX_new;
-        SSL_CONF_CTX_set1_prefix;
-        SSL_CONF_CTX_set_flags;
-        SSL_CONF_CTX_set_ssl;
-        SSL_CONF_CTX_set_ssl_ctx;
-        SSL_CONF_cmd;
-        SSL_CONF_cmd_argv;
-        SSL_CONF_cmd_value_type;
-        SSL_CTX_SRP_CTX_free;
-        SSL_CTX_SRP_CTX_init;
-        SSL_CTX_add_client_CA;
-        SSL_CTX_add_client_custom_ext;
-        SSL_CTX_add_server_custom_ext;
-        SSL_CTX_add_session;
-        SSL_CTX_callback_ctrl;
-        SSL_CTX_check_private_key;
-        SSL_CTX_clear_options;
-        SSL_CTX_config;
-        SSL_CTX_ct_is_enabled;
-        SSL_CTX_ctrl;
-        SSL_CTX_dane_clear_flags;
-        SSL_CTX_dane_enable;
-        SSL_CTX_dane_mtype_set;
-        SSL_CTX_dane_set_flags;
-        SSL_CTX_enable_ct;
-        SSL_CTX_flush_sessions;
-        SSL_CTX_free;
-        SSL_CTX_get0_certificate;
-        SSL_CTX_get0_ctlog_store;
-        SSL_CTX_get0_param;
-        SSL_CTX_get0_privatekey;
-        SSL_CTX_get0_security_ex_data;
-        SSL_CTX_get_cert_store;
-        SSL_CTX_get_ciphers;
-        SSL_CTX_get_client_CA_list;
-        SSL_CTX_get_client_cert_cb;
-        SSL_CTX_get_default_passwd_cb;
-        SSL_CTX_get_default_passwd_cb_userdata;
-        SSL_CTX_get_ex_data;
-        SSL_CTX_get_info_callback;
-        SSL_CTX_get_options;
-        SSL_CTX_get_quiet_shutdown;
-        SSL_CTX_get_security_callback;
-        SSL_CTX_get_security_level;
-        SSL_CTX_get_ssl_method;
-        SSL_CTX_get_timeout;
-        SSL_CTX_get_verify_callback;
-        SSL_CTX_get_verify_depth;
-        SSL_CTX_get_verify_mode;
-        SSL_CTX_has_client_custom_ext;
-        SSL_CTX_load_verify_locations;
-        SSL_CTX_new;
-        SSL_CTX_remove_session;
-        SSL_CTX_sess_get_get_cb;
-        SSL_CTX_sess_get_new_cb;
-        SSL_CTX_sess_get_remove_cb;
-        SSL_CTX_sess_set_get_cb;
-        SSL_CTX_sess_set_new_cb;
-        SSL_CTX_sess_set_remove_cb;
-        SSL_CTX_sessions;
-        SSL_CTX_set0_ctlog_store;
-        SSL_CTX_set0_security_ex_data;
-        SSL_CTX_set1_param;
-        SSL_CTX_set_alpn_protos;
-        SSL_CTX_set_alpn_select_cb;
-        SSL_CTX_set_cert_cb;
-        SSL_CTX_set_cert_store;
-        SSL_CTX_set_cert_verify_callback;
-        SSL_CTX_set_cipher_list;
-        SSL_CTX_set_client_CA_list;
-        SSL_CTX_set_client_cert_cb;
-        SSL_CTX_set_client_cert_engine;
-        SSL_CTX_set_cookie_generate_cb;
-        SSL_CTX_set_cookie_verify_cb;
-        SSL_CTX_set_ct_validation_callback;
-        SSL_CTX_set_ctlog_list_file;
-        SSL_CTX_set_default_ctlog_list_file;
-        SSL_CTX_set_default_passwd_cb;
-        SSL_CTX_set_default_passwd_cb_userdata;
-        SSL_CTX_set_default_read_buffer_len;
-        SSL_CTX_set_default_verify_dir;
-        SSL_CTX_set_default_verify_file;
-        SSL_CTX_set_default_verify_paths;
-        SSL_CTX_set_ex_data;
-        SSL_CTX_set_generate_session_id;
-        SSL_CTX_set_info_callback;
-        SSL_CTX_set_msg_callback;
-        SSL_CTX_set_next_proto_select_cb;
-        SSL_CTX_set_next_protos_advertised_cb;
-        SSL_CTX_set_not_resumable_session_callback;
-        SSL_CTX_set_options;
-        SSL_CTX_set_psk_client_callback;
-        SSL_CTX_set_psk_server_callback;
-        SSL_CTX_set_purpose;
-        SSL_CTX_set_quiet_shutdown;
-        SSL_CTX_set_security_callback;
-        SSL_CTX_set_security_level;
-        SSL_CTX_set_session_id_context;
-        SSL_CTX_set_srp_cb_arg;
-        SSL_CTX_set_srp_client_pwd_callback;
-        SSL_CTX_set_srp_password;
-        SSL_CTX_set_srp_strength;
-        SSL_CTX_set_srp_username;
-        SSL_CTX_set_srp_username_callback;
-        SSL_CTX_set_srp_verify_param_callback;
-        SSL_CTX_set_ssl_version;
-        SSL_CTX_set_timeout;
-        SSL_CTX_set_tlsext_use_srtp;
-        SSL_CTX_set_tmp_dh_callback;
-        SSL_CTX_set_trust;
-        SSL_CTX_set_verify;
-        SSL_CTX_set_verify_depth;
-        SSL_CTX_up_ref;
-        SSL_CTX_use_PrivateKey;
-        SSL_CTX_use_PrivateKey_ASN1;
-        SSL_CTX_use_PrivateKey_file;
-        SSL_CTX_use_RSAPrivateKey;
-        SSL_CTX_use_RSAPrivateKey_ASN1;
-        SSL_CTX_use_RSAPrivateKey_file;
-        SSL_CTX_use_certificate;
-        SSL_CTX_use_certificate_ASN1;
-        SSL_CTX_use_certificate_chain_file;
-        SSL_CTX_use_certificate_file;
-        SSL_CTX_use_psk_identity_hint;
-        SSL_CTX_use_serverinfo;
-        SSL_CTX_use_serverinfo_file;
-        SSL_SESSION_free;
-        SSL_SESSION_get0_cipher;
-        SSL_SESSION_get0_hostname;
-        SSL_SESSION_get0_id_context;
-        SSL_SESSION_get0_peer;
-        SSL_SESSION_get0_ticket;
-        SSL_SESSION_get_compress_id;
-        SSL_SESSION_get_ex_data;
-        SSL_SESSION_get_id;
-        SSL_SESSION_get_master_key;
-        SSL_SESSION_get_protocol_version;
-        SSL_SESSION_get_ticket_lifetime_hint;
-        SSL_SESSION_get_time;
-        SSL_SESSION_get_timeout;
-        SSL_SESSION_has_ticket;
-        SSL_SESSION_new;
-        SSL_SESSION_print;
-        SSL_SESSION_print_fp;
-        SSL_SESSION_print_keylog;
-        SSL_SESSION_set1_id;
-        SSL_SESSION_set1_id_context;
-        SSL_SESSION_set_ex_data;
-        SSL_SESSION_set_time;
-        SSL_SESSION_set_timeout;
-        SSL_SESSION_up_ref;
-        SSL_SRP_CTX_free;
-        SSL_SRP_CTX_init;
-        SSL_accept;
-        SSL_add1_host;
-        SSL_add_client_CA;
-        SSL_add_dir_cert_subjects_to_stack;
-        SSL_add_file_cert_subjects_to_stack;
-        SSL_add_ssl_module;
-        SSL_alert_desc_string;
-        SSL_alert_desc_string_long;
-        SSL_alert_type_string;
-        SSL_alert_type_string_long;
-        SSL_callback_ctrl;
-        SSL_certs_clear;
-        SSL_check_chain;
-        SSL_check_private_key;
-        SSL_clear;
-        SSL_clear_options;
-        SSL_client_version;
-        SSL_config;
-        SSL_connect;
-        SSL_copy_session_id;
-        SSL_ct_is_enabled;
-        SSL_ctrl;
-        SSL_dane_clear_flags;
-        SSL_dane_enable;
-        SSL_dane_set_flags;
-        SSL_dane_tlsa_add;
-        SSL_do_handshake;
-        SSL_dup;
-        SSL_dup_CA_list;
-        SSL_enable_ct;
-        SSL_export_keying_material;
-        SSL_extension_supported;
-        SSL_free;
-        SSL_get0_alpn_selected;
-        SSL_get0_dane;
-        SSL_get0_dane_authority;
-        SSL_get0_dane_tlsa;
-        SSL_get0_next_proto_negotiated;
-        SSL_get0_param;
-        SSL_get0_peer_scts;
-        SSL_get0_peername;
-        SSL_get0_security_ex_data;
-        SSL_get0_verified_chain;
-        SSL_get1_session;
-        SSL_get1_supported_ciphers;
-        SSL_get_SSL_CTX;
-        SSL_get_all_async_fds;
-        SSL_get_certificate;
-        SSL_get_changed_async_fds;
-        SSL_get_cipher_list;
-        SSL_get_ciphers;
-        SSL_get_client_CA_list;
-        SSL_get_client_ciphers;
-        SSL_get_client_random;
-        SSL_get_current_cipher;
-        SSL_get_current_compression;
-        SSL_get_current_expansion;
-        SSL_get_default_passwd_cb;
-        SSL_get_default_passwd_cb_userdata;
-        SSL_get_default_timeout;
-        SSL_get_error;
-        SSL_get_ex_data;
-        SSL_get_ex_data_X509_STORE_CTX_idx;
-        SSL_get_fd;
-        SSL_get_finished;
-        SSL_get_info_callback;
-        SSL_get_options;
-        SSL_get_peer_cert_chain;
-        SSL_get_peer_certificate;
-        SSL_get_peer_finished;
-        SSL_get_privatekey;
-        SSL_get_psk_identity;
-        SSL_get_psk_identity_hint;
-        SSL_get_quiet_shutdown;
-        SSL_get_rbio;
-        SSL_get_read_ahead;
-        SSL_get_rfd;
-        SSL_get_security_callback;
-        SSL_get_security_level;
-        SSL_get_selected_srtp_profile;
-        SSL_get_server_random;
-        SSL_get_servername;
-        SSL_get_servername_type;
-        SSL_get_session;
-        SSL_get_shared_ciphers;
-        SSL_get_shared_sigalgs;
-        SSL_get_shutdown;
-        SSL_get_sigalgs;
-        SSL_get_srp_N;
-        SSL_get_srp_g;
-        SSL_get_srp_userinfo;
-        SSL_get_srp_username;
-        SSL_get_srtp_profiles;
-        SSL_get_ssl_method;
-        SSL_get_state;
-        SSL_get_verify_callback;
-        SSL_get_verify_depth;
-        SSL_get_verify_mode;
-        SSL_get_verify_result;
-        SSL_get_version;
-        SSL_get_wbio;
-        SSL_get_wfd;
-        SSL_has_matching_session_id;
-        SSL_has_pending;
-        SSL_in_before;
-        SSL_in_init;
-        SSL_is_dtls;
-        SSL_is_init_finished;
-        SSL_is_server;
-        SSL_load_client_CA_file;
-        SSL_new;
-        SSL_peek;
-        SSL_pending;
-        SSL_read;
-        SSL_renegotiate;
-        SSL_renegotiate_abbreviated;
-        SSL_renegotiate_pending;
-        SSL_rstate_string;
-        SSL_rstate_string_long;
-        SSL_select_next_proto;
-        SSL_session_reused;
-        SSL_set0_rbio;
-        SSL_set0_security_ex_data;
-        SSL_set0_wbio;
-        SSL_set1_host;
-        SSL_set1_param;
-        SSL_set_SSL_CTX;
-        SSL_set_accept_state;
-        SSL_set_alpn_protos;
-        SSL_set_bio;
-        SSL_set_cert_cb;
-        SSL_set_cipher_list;
-        SSL_set_client_CA_list;
-        SSL_set_connect_state;
-        SSL_set_ct_validation_callback;
-        SSL_set_debug;
-        SSL_set_default_passwd_cb;
-        SSL_set_default_passwd_cb_userdata;
-        SSL_set_default_read_buffer_len;
-        SSL_set_ex_data;
-        SSL_set_fd;
-        SSL_set_generate_session_id;
-        SSL_set_hostflags;
-        SSL_set_info_callback;
-        SSL_set_msg_callback;
-        SSL_set_not_resumable_session_callback;
-        SSL_set_options;
-        SSL_set_psk_client_callback;
-        SSL_set_psk_server_callback;
-        SSL_set_purpose;
-        SSL_set_quiet_shutdown;
-        SSL_set_read_ahead;
-        SSL_set_rfd;
-        SSL_set_security_callback;
-        SSL_set_security_level;
-        SSL_set_session;
-        SSL_set_session_id_context;
-        SSL_set_session_secret_cb;
-        SSL_set_session_ticket_ext;
-        SSL_set_session_ticket_ext_cb;
-        SSL_set_shutdown;
-        SSL_set_srp_server_param;
-        SSL_set_srp_server_param_pw;
-        SSL_set_ssl_method;
-        SSL_set_tlsext_use_srtp;
-        SSL_set_tmp_dh_callback;
-        SSL_set_trust;
-        SSL_set_verify;
-        SSL_set_verify_depth;
-        SSL_set_verify_result;
-        SSL_set_wfd;
-        SSL_shutdown;
-        SSL_srp_server_param_with_username;
-        SSL_state_string;
-        SSL_state_string_long;
-        SSL_up_ref;
-        SSL_use_PrivateKey;
-        SSL_use_PrivateKey_ASN1;
-        SSL_use_PrivateKey_file;
-        SSL_use_RSAPrivateKey;
-        SSL_use_RSAPrivateKey_ASN1;
-        SSL_use_RSAPrivateKey_file;
-        SSL_use_certificate;
-        SSL_use_certificate_ASN1;
-        SSL_use_certificate_chain_file;
-        SSL_use_certificate_file;
-        SSL_use_psk_identity_hint;
-        SSL_version;
-        SSL_waiting_for_async;
-        SSL_want;
-        SSL_write;
-        TLS_client_method;
-        TLS_method;
-        TLS_server_method;
-        TLSv1_1_client_method;
-        TLSv1_1_method;
-        TLSv1_1_server_method;
-        TLSv1_2_client_method;
-        TLSv1_2_method;
-        TLSv1_2_server_method;
-        TLSv1_client_method;
-        TLSv1_method;
-        TLSv1_server_method;
-        d2i_SSL_SESSION;
-        i2d_SSL_SESSION;
-};
-
-OPENSSL_1_1_0d {
-    global:
-        SSL_COMP_get0_name;
-        SSL_COMP_get_id;
-} OPENSSL_1_1_0;
-
-OPENSSL_1_1_1 {
-    global:
-        DTLS_get_data_mtu;
-        DTLS_set_timer_cb;
-        OPENSSL_cipher_name;
-        SSL_CIPHER_get_handshake_digest;
-        SSL_CIPHER_get_protocol_id;
-        SSL_CTX_add1_to_CA_list;
-        SSL_CTX_add_custom_ext;
-        SSL_CTX_get0_CA_list;
-        SSL_CTX_get_keylog_callback;
-        SSL_CTX_get_max_early_data;
-        SSL_CTX_get_num_tickets;
-        SSL_CTX_get_record_padding_callback_arg;
-        SSL_CTX_get_recv_max_early_data;
-        SSL_CTX_set0_CA_list;
-        SSL_CTX_set1_cert_store;
-        SSL_CTX_set_allow_early_data_cb;
-        SSL_CTX_set_block_padding;
-        SSL_CTX_set_ciphersuites;
-        SSL_CTX_set_client_hello_cb;
-        SSL_CTX_set_keylog_callback;
-        SSL_CTX_set_max_early_data;
-        SSL_CTX_set_num_tickets;
-        SSL_CTX_set_post_handshake_auth;
-        SSL_CTX_set_psk_find_session_callback;
-        SSL_CTX_set_psk_use_session_callback;
-        SSL_CTX_set_record_padding_callback;
-        SSL_CTX_set_record_padding_callback_arg;
-        SSL_CTX_set_recv_max_early_data;
-        SSL_CTX_set_session_ticket_cb;
-        SSL_CTX_set_stateless_cookie_generate_cb;
-        SSL_CTX_set_stateless_cookie_verify_cb;
-        SSL_CTX_set_tlsext_max_fragment_length;
-        SSL_CTX_use_cert_and_key;
-        SSL_CTX_use_serverinfo_ex;
-        SSL_SESSION_dup;
-        SSL_SESSION_get0_alpn_selected;
-        SSL_SESSION_get0_ticket_appdata;
-        SSL_SESSION_get_max_early_data;
-        SSL_SESSION_get_max_fragment_length;
-        SSL_SESSION_is_resumable;
-        SSL_SESSION_set1_alpn_selected;
-        SSL_SESSION_set1_hostname;
-        SSL_SESSION_set1_master_key;
-        SSL_SESSION_set1_ticket_appdata;
-        SSL_SESSION_set_cipher;
-        SSL_SESSION_set_max_early_data;
-        SSL_SESSION_set_protocol_version;
-        SSL_add1_to_CA_list;
-        SSL_alloc_buffers;
-        SSL_bytes_to_cipher_list;
-        SSL_client_hello_get0_ciphers;
-        SSL_client_hello_get0_compression_methods;
-        SSL_client_hello_get0_ext;
-        SSL_client_hello_get0_legacy_version;
-        SSL_client_hello_get0_random;
-        SSL_client_hello_get0_session_id;
-        SSL_client_hello_get1_extensions_present;
-        SSL_client_hello_isv2;
-        SSL_export_keying_material_early;
-        SSL_free_buffers;
-        SSL_get0_CA_list;
-        SSL_get0_peer_CA_list;
-        SSL_get_early_data_status;
-        SSL_get_key_update_type;
-        SSL_get_max_early_data;
-        SSL_get_num_tickets;
-        SSL_get_peer_signature_type_nid;
-        SSL_get_pending_cipher;
-        SSL_get_record_padding_callback_arg;
-        SSL_get_recv_max_early_data;
-        SSL_key_update;
-        SSL_peek_ex;
-        SSL_read_early_data;
-        SSL_read_ex;
-        SSL_set0_CA_list;
-        SSL_set_allow_early_data_cb;
-        SSL_set_block_padding;
-        SSL_set_ciphersuites;
-        SSL_set_max_early_data;
-        SSL_set_num_tickets;
-        SSL_set_post_handshake_auth;
-        SSL_set_psk_find_session_callback;
-        SSL_set_psk_use_session_callback;
-        SSL_set_record_padding_callback;
-        SSL_set_record_padding_callback_arg;
-        SSL_set_recv_max_early_data;
-        SSL_set_tlsext_max_fragment_length;
-        SSL_stateless;
-        SSL_use_cert_and_key;
-        SSL_verify_client_post_handshake;
-        SSL_write_early_data;
-        SSL_write_ex;
-} OPENSSL_1_1_0d;
-
-OPENSSL_1_1_1a {
-    global:
-        SSL_get_signature_type_nid;
-    local: *;
-} OPENSSL_1_1_1;
-
-OPENSSL_1_1_1i {
-    global:
-        SSL_CIPHER_get_prf_nid;
-        SSL_CTX_set_quic_method;
-        SSL_get_peer_quic_transport_params;
-        SSL_get_peer_quic_transport_version;
-        SSL_get_quic_transport_version;
-        SSL_is_quic;
-        SSL_process_quic_post_handshake;
-        SSL_provide_quic_data;
-        SSL_quic_max_handshake_flight_len;
-        SSL_quic_read_level;
-        SSL_quic_write_level;
-        SSL_set_quic_method;
-        SSL_set_quic_transport_params;
-        SSL_set_quic_transport_version;
-        SSL_set_quic_use_legacy_codepoint;
-} OPENSSL_1_1_1a;
-
-OPENSSL_1_1_1j {
-    global:
-        SSL_set_quic_early_data_enabled;
-} OPENSSL_1_1_1i;
-
-OPENSSL_1_1_1k {
-    global:
-        SSL_new_session_ticket;
-    local: *;
-} OPENSSL_1_1_1j;
-
-
diff --git a/contrib/libs/openssl/openssl.package.json b/contrib/libs/openssl/openssl.package.json
deleted file mode 100644
index e98964e5067..00000000000
--- a/contrib/libs/openssl/openssl.package.json
+++ /dev/null
@@ -1,37 +0,0 @@
-{
-  "meta": {
-    "name": "libyandex-openssl-dev",
-    "version": "1.0.2j-r{revision}",
-    "maintainer": "Sergey Mironov <[email protected]>",
-    "description": "Statically linked OpenSSL from arcadia, headers\nWith Yandex' patches\nApproved by security"
-  },
-  "build": {
-    "targets": [
-      "contrib/libs/openssl"
-    ]
-  },
-  "data": [
-    {
-      "source": {
-        "type": "BUILD_OUTPUT",
-        "path": "contrib/libs/openssl",
-        "files": [
-          "libcontrib-libs-openssl.a"
-        ]
-      },
-      "destination": {
-        "path": "/usr/lib/"
-      }
-    },
-    {
-      "source": {
-        "path": "contrib/libs/openssl/include/openssl",
-        "scheme": "svn",
-        "type": "ARCADIA"
-      },
-      "destination": {
-        "path": "/usr/include/yandex-newssl/"
-      }
-    }
-  ]
-}
diff --git a/util/ysafeptr.cpp b/util/ysafeptr.cpp
index 96f25140673..db2ff21ec0c 100644
--- a/util/ysafeptr.cpp
+++ b/util/ysafeptr.cpp
@@ -1,5 +1,7 @@
 #include "ysafeptr.h"
 
+#include <util/system/sanitizers.h>
+
 #ifdef CHECK_YPTR2
 Y_POD_THREAD(bool)
 IObjectBase::DisableThreadCheck;
@@ -24,6 +26,11 @@ void IObjectBase::ReleaseObjComplete(int nMask) {
     }
 }
 ////////////////////////////////////////////////////////////////////////////////////////////////////
+void IObjectBase::UnpoisonCounters() noexcept {
+    NSan::Unpoison(&ObjData, sizeof(ObjData));
+    NSan::Unpoison(&RefData, sizeof(RefData));
+}
+////////////////////////////////////////////////////////////////////////////////////////////////////
 void IObjectBase::ReleaseRefComplete() {
     assert(RefData == 0);
     if ((ObjData & 0x3fffffff) == 0) {
diff --git a/util/ysafeptr.h b/util/ysafeptr.h
index ab5f26fb1ba..807ed63b67e 100644
--- a/util/ysafeptr.h
+++ b/util/ysafeptr.h
@@ -91,6 +91,8 @@ protected:
     // function should clear contents of object, easy to implement via consequent calls to
     // destructor and constructor, this function should not be called directly, use Clear()
     virtual void DestroyContents() = 0;
+    // Unpoison ObjData/RefData to mute deliberate use-after-dtor
+    void UnpoisonCounters() noexcept;
     virtual ~IObjectBase() = default;
     inline void CopyValidFlag(const IObjectBase& a) {
         ObjData &= 0x7fffffff;
@@ -207,6 +209,7 @@ public:                                                           \
 protected:                                                        \
     virtual void DestroyContents() override {                     \
         this->~classname();                                       \
+        this->UnpoisonCounters();                                 \
         int nHoldRefs = this->RefData, nHoldObjs = this->ObjData; \
         new (this) classname();                                   \
         this->RefData += nHoldRefs;                               \
diff --git a/yql/essentials/core/peephole_opt/yql_opt_peephole_physical.cpp b/yql/essentials/core/peephole_opt/yql_opt_peephole_physical.cpp
index 2c82652f573..1b74ca1e817 100644
--- a/yql/essentials/core/peephole_opt/yql_opt_peephole_physical.cpp
+++ b/yql/essentials/core/peephole_opt/yql_opt_peephole_physical.cpp
@@ -3143,6 +3143,30 @@ TExprNode::TPtr ExpandPartitionsByKeys(const TExprNode::TPtr& node, TExprContext
     return ctx.ReplaceNode(node->Tail().TailPtr(), node->Tail().Head().Head(), std::move(sort));
 }
 
+TExprNode::TPtr ExpandLPartitionsByKeys(const TExprNode::TPtr& node, TExprContext& ctx) {
+    YQL_CLOG(DEBUG, CorePeepHole) << "Expand " << node->Content();
+    return ctx.Builder(node->Pos())
+        .Callable("Block")
+            .Lambda(0)
+                .Param("parent")
+                .Callable("Collect")
+                    .Callable(0, "PartitionsByKeys")
+                        .Callable(0, "Iterator")
+                            .Add(0, node->HeadPtr())
+                            .Callable(1, "DependsOn")
+                                .Arg(0, "parent")
+                            .Seal()
+                        .Seal()
+                        .Add(1, node->ChildPtr(1))
+                        .Add(2, node->ChildPtr(2))
+                        .Add(3, node->ChildPtr(3))
+                        .Add(4, node->ChildPtr(4))
+                    .Seal()
+                .Seal()
+            .Seal()
+        .Seal().Build();
+}
+
 TExprNode::TPtr ExpandIsKeySwitch(const TExprNode::TPtr& node, TExprContext& ctx) {
     YQL_CLOG(DEBUG, CorePeepHole) << "Expand " << node->Content();
     return ctx.Builder(node->Pos())
@@ -9349,6 +9373,7 @@ struct TPeepHoleRules {
         {"Fold1Map", &CleckClosureOnUpperLambdaOverList<1U, 2U>},
         {"Chain1Map", &CleckClosureOnUpperLambdaOverList<1U, 2U>},
         {"PartitionsByKeys", &ExpandPartitionsByKeys},
+        {"LPartitionsByKeys", &ExpandLPartitionsByKeys},
         {"DictItems", &MapForOptionalContainer},
         {"DictKeys", &MapForOptionalContainer},
         {"DictPayloads", &MapForOptionalContainer},
diff --git a/yql/essentials/core/type_ann/type_ann_blocks.cpp b/yql/essentials/core/type_ann/type_ann_blocks.cpp
index eee3e6a8db3..dd5e3dae0a4 100644
--- a/yql/essentials/core/type_ann/type_ann_blocks.cpp
+++ b/yql/essentials/core/type_ann/type_ann_blocks.cpp
@@ -1377,10 +1377,24 @@ IGraphTransformer::TStatus BlockPgCallWrapper(const TExprNode::TPtr& input, TExp
         }
 
         auto content = setting->Head().Content();
-        ctx.Expr.AddError(TIssue(ctx.Expr.GetPosition(input->Pos()),
-            TStringBuilder() << "Unexpected setting " << content << " in function " << name));
+        if (content == "collation_oid") {
+            // BlockPgResolvedCall is only ever built by rewriting an already-resolved
+            // PgResolvedCall (see the peephole rewrite in yql_opt_peephole_physical.cpp),
+            // so its settings never carry a raw "collation" name - only the already-resolved
+            // "collation_oid", trusted as-is here, same as the analogous case in PgCallWrapper.
+            if (!EnsureTupleSize(*setting, 2, ctx.Expr)) {
+                return IGraphTransformer::TStatus::Error;
+            }
 
-        return IGraphTransformer::TStatus::Error;
+            if (!EnsureAtom(setting->Tail(), ctx.Expr)) {
+                return IGraphTransformer::TStatus::Error;
+            }
+        } else {
+            ctx.Expr.AddError(TIssue(ctx.Expr.GetPosition(input->Pos()),
+                TStringBuilder() << "Unexpected setting " << content << " in function " << name));
+
+            return IGraphTransformer::TStatus::Error;
+        }
     }
 
     TVector<ui32> argTypes;
diff --git a/yql/essentials/core/type_ann/type_ann_core.cpp b/yql/essentials/core/type_ann/type_ann_core.cpp
index 1fd05710857..74dca3df57a 100644
--- a/yql/essentials/core/type_ann/type_ann_core.cpp
+++ b/yql/essentials/core/type_ann/type_ann_core.cpp
@@ -16087,7 +16087,8 @@ template <NKikimr::NUdf::EDataSlot DataSlot>
         Functions["ToBytes"] = &ToBytesWrapper;
         Functions["GroupByKey"] = &GroupByKeyWrapper;
         Functions["PartitionByKey"] = &PartitionByKeyWrapper;
-        Functions["PartitionsByKeys"] = &PartitionsByKeysWrapper;
+        Functions["PartitionsByKeys"] = &PartitionsByKeysWrapper<false>;
+        Functions["LPartitionsByKeys"] = &PartitionsByKeysWrapper<true>;
         Functions["Reverse"] = &ReverseWrapper;
         ExtFunctions["Skip"] = &TakeWrapperEx;
         ExtFunctions["Take"] = &TakeWrapperEx;
diff --git a/yql/essentials/core/type_ann/type_ann_list.cpp b/yql/essentials/core/type_ann/type_ann_list.cpp
index bfdcb22552b..d2cd11fad47 100644
--- a/yql/essentials/core/type_ann/type_ann_list.cpp
+++ b/yql/essentials/core/type_ann/type_ann_list.cpp
@@ -4369,6 +4369,7 @@ namespace {
         return IGraphTransformer::TStatus::Ok;
     }
 
+    template<bool LPartitionsByKeys>
     IGraphTransformer::TStatus PartitionsByKeysWrapper(const TExprNode::TPtr& input, TExprNode::TPtr& output, TContext& ctx) {
         Y_UNUSED(output);
         if (!EnsureArgsCount(*input, 5, ctx.Expr)) {
@@ -4381,8 +4382,15 @@ namespace {
         }
 
         const TTypeAnnotationNode* itemType = nullptr;
-        if (!EnsureNewSeqType<false>(input->Head(), ctx.Expr, &itemType)) {
-            return IGraphTransformer::TStatus::Error;
+        if constexpr (LPartitionsByKeys) {
+            if (!EnsureListType(input->Head(), ctx.Expr)) {
+                return IGraphTransformer::TStatus::Error;
+            }
+            itemType = input->Head().GetTypeAnn()->Cast<TListExprType>()->GetItemType();
+        } else {
+            if (!EnsureNewSeqType<false>(input->Head(), ctx.Expr, &itemType)) {
+                return IGraphTransformer::TStatus::Error;
+            }
         }
 
         auto& lambdaKeySelector = input->ChildRef(1);
@@ -4450,7 +4458,11 @@ namespace {
             return IGraphTransformer::TStatus::Error;
         }
 
-        if (!UpdateLambdaAllArgumentsTypes(lambdaFinalHandler, { input->Head().GetTypeAnn() }, ctx.Expr)) {
+        const auto lambdaFinalHandlerArgType = LPartitionsByKeys
+            ? ctx.Expr.MakeType<TStreamExprType>(itemType)
+            : input->Head().GetTypeAnn();
+
+        if (!UpdateLambdaAllArgumentsTypes(lambdaFinalHandler, { lambdaFinalHandlerArgType }, ctx.Expr)) {
             return IGraphTransformer::TStatus::Error;
         }
 
@@ -4467,10 +4479,17 @@ namespace {
             return IGraphTransformer::TStatus::Error;
         }
 
-        input->SetTypeAnn(lambdaFinalHandler->GetTypeAnn());
+        if constexpr (LPartitionsByKeys) {
+            input->SetTypeAnn(ctx.Expr.MakeType<TListExprType>(&GetSeqItemType(*lambdaFinalHandler->GetTypeAnn())));
+        } else {
+            input->SetTypeAnn(lambdaFinalHandler->GetTypeAnn());
+        }
         return IGraphTransformer::TStatus::Ok;
     }
 
+    template IGraphTransformer::TStatus PartitionsByKeysWrapper<true>(const TExprNode::TPtr& input, TExprNode::TPtr& output, TContext& ctx);
+    template IGraphTransformer::TStatus PartitionsByKeysWrapper<false>(const TExprNode::TPtr& input, TExprNode::TPtr& output, TContext& ctx);
+
     IGraphTransformer::TStatus ReverseWrapper(const TExprNode::TPtr& input, TExprNode::TPtr& output, TContext& ctx) {
         if (!EnsureArgsCount(*input, 1, ctx.Expr)) {
             return IGraphTransformer::TStatus::Error;
diff --git a/yql/essentials/core/type_ann/type_ann_list.h b/yql/essentials/core/type_ann/type_ann_list.h
index 026a0e38a19..5a4d8038e74 100644
--- a/yql/essentials/core/type_ann/type_ann_list.h
+++ b/yql/essentials/core/type_ann/type_ann_list.h
@@ -89,6 +89,7 @@ namespace NYql::NTypeAnnImpl {
     IGraphTransformer::TStatus SessionWindowTraitsWrapper(const TExprNode::TPtr& input, TExprNode::TPtr& output, TContext& ctx);
     IGraphTransformer::TStatus GroupByKeyWrapper(const TExprNode::TPtr& input, TExprNode::TPtr& output, TContext& ctx);
     IGraphTransformer::TStatus PartitionByKeyWrapper(const TExprNode::TPtr& input, TExprNode::TPtr& output, TContext& ctx);
+    template<bool LPartitionsByKeys>
     IGraphTransformer::TStatus PartitionsByKeysWrapper(const TExprNode::TPtr& input, TExprNode::TPtr& output, TContext& ctx);
     IGraphTransformer::TStatus ReverseWrapper(const TExprNode::TPtr& input, TExprNode::TPtr& output, TContext& ctx);
     IGraphTransformer::TStatus TakeWrapperEx(const TExprNode::TPtr& input, TExprNode::TPtr& output, TExtContext& ctx);
diff --git a/yql/essentials/core/type_ann/type_ann_pg.cpp b/yql/essentials/core/type_ann/type_ann_pg.cpp
index accf9548635..18255f683b4 100644
--- a/yql/essentials/core/type_ann/type_ann_pg.cpp
+++ b/yql/essentials/core/type_ann/type_ann_pg.cpp
@@ -254,6 +254,34 @@ IGraphTransformer::TStatus PgCallWrapper(const TExprNode::TPtr& input, TExprNode
             }
 
             refinedType = NPg::LookupType(TString(setting->Tail().Content())).TypeId;
+        } else if (content == "collation") {
+            if (!EnsureTupleSize(*setting, 2, ctx.Expr)) {
+                return IGraphTransformer::TStatus::Error;
+            }
+
+            if (!EnsureAtom(setting->Tail(), ctx.Expr)) {
+                return IGraphTransformer::TStatus::Error;
+            }
+
+            TString collationName(setting->Tail().Content());
+            try {
+                NPg::LookupCollation(collationName);
+            } catch (const yexception& e) {
+                ctx.Expr.AddError(TIssue(ctx.Expr.GetPosition(input->Pos()),
+                    TStringBuilder() << "Failed to resolve collation \"" << collationName << "\" for function " << name << ": " << e.what()));
+                return IGraphTransformer::TStatus::Error;
+            }
+        } else if (content == "collation_oid") {
+            // Resolved collation oid, computed once from the "collation" setting above
+            // when PgResolvedCall was built (see below) - trusted as-is, same as the
+            // resolved proc oid in input->Child(1) is trusted without re-resolving the name.
+            if (!EnsureTupleSize(*setting, 2, ctx.Expr)) {
+                return IGraphTransformer::TStatus::Error;
+            }
+
+            if (!EnsureAtom(setting->Tail(), ctx.Expr)) {
+                return IGraphTransformer::TStatus::Error;
+            }
         } else {
             ctx.Expr.AddError(TIssue(ctx.Expr.GetPosition(input->Pos()),
                 TStringBuilder() << "Unexpected setting " << content << " in function " << name));
@@ -373,6 +401,32 @@ IGraphTransformer::TStatus PgCallWrapper(const TExprNode::TPtr& input, TExprNode
                     children.push_back(std::move(node));
                 }
 
+                // If the call had an explicit COLLATE, resolve it to a stable oid (see
+                // NPg::LookupCollation) and replace the "collation" (name) setting with the
+                // resolved "collation_oid" one - the name has done its job (validation) and
+                // the oid is now the single source of truth, same as how the function name
+                // atom stays but the unresolved settings entry itself doesn't need to persist.
+                auto& settingsNode = children[argStart - 1];
+                for (const auto& setting : settingsNode->Children()) {
+                    if (setting->Head().Content() != "collation") {
+                        continue;
+                    }
+
+                    auto collationOid = NPg::LookupCollation(TString(setting->Tail().Content())).Oid;
+                    TExprNode::TListType newSettings;
+                    for (const auto& other : settingsNode->Children()) {
+                        if (other->Head().Content() != "collation") {
+                            newSettings.push_back(other);
+                        }
+                    }
+                    newSettings.push_back(ctx.Expr.NewList(input->Pos(), {
+                        ctx.Expr.NewAtom(input->Pos(), "collation_oid"),
+                        ctx.Expr.NewAtom(input->Pos(), ToString(collationOid)),
+                    }));
+                    settingsNode = ctx.Expr.NewList(input->Pos(), std::move(newSettings));
+                    break;
+                }
+
                 if (proc.Lang == NPg::LangSQL) {
                     if (!proc.ExprNode) {
                         throw yexception() << "Function " << proc.Name << " has no implementation";
diff --git a/yql/essentials/minikql/mkql_program_builder.cpp b/yql/essentials/minikql/mkql_program_builder.cpp
index 7a902067c85..87ed9bbbeb7 100644
--- a/yql/essentials/minikql/mkql_program_builder.cpp
+++ b/yql/essentials/minikql/mkql_program_builder.cpp
@@ -6185,23 +6185,59 @@ TRuntimeNode TProgramBuilder::PgConst(TPgType* pgType, const std::string_view& v
 
 TRuntimeNode TProgramBuilder::PgResolvedCall(bool useContext, const std::string_view& name,
                                              ui32 id, const TArrayRef<const TRuntimeNode>& args,
-                                             TType* returnType, bool rangeFunction) {
-    TCallableBuilder callableBuilder(Env_, __func__, returnType);
-    callableBuilder.Add(NewDataLiteral(useContext));
-    callableBuilder.Add(NewDataLiteral(rangeFunction));
-    callableBuilder.Add(NewDataLiteral<NUdf::EDataSlot::String>(name));
-    callableBuilder.Add(NewDataLiteral(id));
-    for (const auto& arg : args) {
-        callableBuilder.Add(arg);
+                                             TType* returnType, bool rangeFunction, ui32 collationOid) {
+    // On old runtimes, always use the "PgResolvedCall" callable exactly as before (and
+    // explicit COLLATE, which needs the collation oid slot, isn't representable at all).
+    // Once the runtime is new enough, ALWAYS use the distinct "PgResolvedCall2" callable -
+    // with an extra collation oid slot right after `id` - even when collationOid is 0, so
+    // that "PgResolvedCall" stops being emitted entirely once the whole fleet is upgraded
+    // past this version, and its read-side support can eventually be deleted. The two
+    // shapes are told apart by callable name rather than input count/type, since an arg's
+    // own static type can legitimately be non-Pg (e.g. a NULL literal).
+    if constexpr (RuntimeVersion < 81U) {
+        Y_ENSURE(collationOid == 0, "Explicit COLLATE requires minikql runtime version >= 81, current: " << RuntimeVersion);
+        TCallableBuilder callableBuilder(Env_, "PgResolvedCall", returnType);
+        callableBuilder.Add(NewDataLiteral(useContext));
+        callableBuilder.Add(NewDataLiteral(rangeFunction));
+        callableBuilder.Add(NewDataLiteral<NUdf::EDataSlot::String>(name));
+        callableBuilder.Add(NewDataLiteral(id));
+        for (const auto& arg : args) {
+            callableBuilder.Add(arg);
+        }
+        return TRuntimeNode(callableBuilder.Build(), /*isImmediate=*/false);
+    } else {
+        TCallableBuilder callableBuilder(Env_, "PgResolvedCall2", returnType);
+        callableBuilder.Add(NewDataLiteral(useContext));
+        callableBuilder.Add(NewDataLiteral(rangeFunction));
+        callableBuilder.Add(NewDataLiteral<NUdf::EDataSlot::String>(name));
+        callableBuilder.Add(NewDataLiteral(id));
+        callableBuilder.Add(NewDataLiteral(collationOid));
+        for (const auto& arg : args) {
+            callableBuilder.Add(arg);
+        }
+        return TRuntimeNode(callableBuilder.Build(), /*isImmediate=*/false);
     }
-    return TRuntimeNode(callableBuilder.Build(), /*isImmediate=*/false);
 }
 
 TRuntimeNode TProgramBuilder::BlockPgResolvedCall(const std::string_view& name, ui32 id,
-                                                  const TArrayRef<const TRuntimeNode>& args, TType* returnType) {
-    TCallableBuilder callableBuilder(Env_, __func__, returnType);
+                                                  const TArrayRef<const TRuntimeNode>& args, TType* returnType,
+                                                  ui32 collationOid) {
+    // Mirrors TProgramBuilder::PgResolvedCall - see the comment there.
+    if constexpr (RuntimeVersion < 81U) {
+        Y_ENSURE(collationOid == 0, "Explicit COLLATE requires minikql runtime version >= 81, current: " << RuntimeVersion);
+        TCallableBuilder callableBuilder(Env_, "BlockPgResolvedCall", returnType);
+        callableBuilder.Add(NewDataLiteral<NUdf::EDataSlot::String>(name));
+        callableBuilder.Add(NewDataLiteral(id));
+        for (const auto& arg : args) {
+            callableBuilder.Add(arg);
+        }
+        return TRuntimeNode(callableBuilder.Build(), /*isImmediate=*/false);
+    }
+
+    TCallableBuilder callableBuilder(Env_, "BlockPgResolvedCall2", returnType);
     callableBuilder.Add(NewDataLiteral<NUdf::EDataSlot::String>(name));
     callableBuilder.Add(NewDataLiteral(id));
+    callableBuilder.Add(NewDataLiteral(collationOid));
     for (const auto& arg : args) {
         callableBuilder.Add(arg);
     }
diff --git a/yql/essentials/minikql/mkql_program_builder.h b/yql/essentials/minikql/mkql_program_builder.h
index 7499782e162..32fccf7c7c8 100644
--- a/yql/essentials/minikql/mkql_program_builder.h
+++ b/yql/essentials/minikql/mkql_program_builder.h
@@ -288,7 +288,8 @@ public:
     TRuntimeNode BlockToPg(TRuntimeNode input, TType* returnType);
     TRuntimeNode BlockFromPg(TRuntimeNode input, TType* returnType);
     TRuntimeNode BlockPgResolvedCall(const std::string_view& name, ui32 id,
-                                     const TArrayRef<const TRuntimeNode>& args, TType* returnType);
+                                     const TArrayRef<const TRuntimeNode>& args, TType* returnType,
+                                     ui32 collationOid);
     TRuntimeNode BlockStorage(TRuntimeNode list, TType* returnType);
     TRuntimeNode BlockMapJoinIndex(TRuntimeNode blockStorage, TType* listItemType, const TArrayRef<const ui32>& keyColumns, bool any, TType* returnType);
     TRuntimeNode BlockMapJoinCore(TRuntimeNode leftStream, TRuntimeNode rightBlockStorage, TType* rightListItemType, EJoinKind joinKind,
@@ -750,7 +751,8 @@ public:
 
     TRuntimeNode PgConst(TPgType* pgType, const std::string_view& value, TRuntimeNode typeMod = {});
     TRuntimeNode PgResolvedCall(bool useContext, const std::string_view& name, ui32 id,
-                                const TArrayRef<const TRuntimeNode>& args, TType* returnType, bool rangeFunction);
+                                const TArrayRef<const TRuntimeNode>& args, TType* returnType, bool rangeFunction,
+                                ui32 collationOid);
     TRuntimeNode PgCast(TRuntimeNode input, TType* returnType, TRuntimeNode typeMod = {});
     TRuntimeNode FromPg(TRuntimeNode input, TType* returnType);
     TRuntimeNode ToPg(TRuntimeNode input, TType* returnType);
diff --git a/yql/essentials/parser/pg_catalog/catalog.cpp b/yql/essentials/parser/pg_catalog/catalog.cpp
index 88a0a8ac1fc..847bdb6f236 100644
--- a/yql/essentials/parser/pg_catalog/catalog.cpp
+++ b/yql/essentials/parser/pg_catalog/catalog.cpp
@@ -59,6 +59,8 @@ using TAggregations = THashMap<ui32, TAggregateDesc>;
 
 using TAms = THashMap<ui32, TAmDesc>;
 
+using TCollations = THashMap<ui32, TCollationDesc>;
+
 using TNamespaces = THashMap<decltype(TNamespaceDesc::Oid), TNamespaceDesc>;
 
 using TOpFamilies = THashMap<TString, TOpFamilyDesc>;
@@ -1299,6 +1301,53 @@ private:
     TAms& Ams_;
 };
 
+class TCollationsParser: public TParser {
+public:
+    explicit TCollationsParser(TCollations& collations)
+        : Collations_(collations)
+    {
+    }
+
+    void OnKey(const TString& key, const TString& value) override {
+        if (key == "oid") {
+            CurrDesc_.Oid = FromString<ui32>(value);
+        } else if (key == "descr") {
+            CurrDesc_.Descr = value;
+        } else if (key == "collname") {
+            CurrDesc_.Name = value;
+        } else if (key == "collprovider") {
+            Y_ENSURE(value.size() == 1);
+            switch (value[0]) {
+                case (char)ECollationProvider::Default:
+                case (char)ECollationProvider::Icu:
+                case (char)ECollationProvider::Libc:
+                    CurrDesc_.Provider = (ECollationProvider)value[0];
+                    break;
+                default:
+                    throw yexception() << "Unknown collprovider value: " << value;
+            }
+        } else if (key == "collencoding") {
+            CurrDesc_.Encoding = FromString<i32>(value);
+        } else if (key == "collcollate") {
+            CurrDesc_.Collate = value;
+        } else if (key == "collctype") {
+            CurrDesc_.Ctype = value;
+        } else if (key == "colliculocale") {
+            CurrDesc_.IcuLocale = value;
+        }
+    }
+
+    void OnFinish() override {
+        Y_ENSURE(!CurrDesc_.Name.empty());
+        Collations_[CurrDesc_.Oid] = std::move(CurrDesc_);
+        CurrDesc_ = TCollationDesc();
+    }
+
+private:
+    TCollationDesc CurrDesc_;
+    TCollations& Collations_;
+};
+
 class TAmProcsParser: public TParser {
 public:
     TAmProcsParser(TAmProcs& amProcs, const THashMap<TString, ui32>& typeByName,
@@ -1582,6 +1631,13 @@ TAms ParseAms(const TString& dat) {
     return ret;
 }
 
+TCollations ParseCollations(const TString& dat) {
+    TCollations ret;
+    TCollationsParser parser(ret);
+    parser.Do(dat);
+    return ret;
+}
+
 TLanguages ParseLanguages(const TString& dat) {
     TLanguages ret;
     TLanguagesParser parser(ret);
@@ -1634,6 +1690,14 @@ const char* AllowedProcsRaw[] = {
 #include "postgis_procs.h"
 };
 
+// Locale names known to the ICU library pg_collation_icu.generated.h was generated from
+// (see gen_icu_collations). Append-only: a locale's position here becomes part of its
+// collation oid (see IcuCollationOidBase below), so it must never change once assigned.
+// NOLINTNEXTLINE(modernize-avoid-c-arrays)
+const char* AllIcuCollationLocalesRaw[] = {
+#include "pg_collation_icu.generated.h"
+};
+
 struct TCatalog: public IExtensionSqlBuilder {
     TCatalog() {
         Init();
@@ -1733,6 +1797,8 @@ struct TCatalog: public IExtensionSqlBuilder {
         Y_ENSURE(NResource::FindExact("pg_conversion.dat", &conversionData));
         TString amData;
         Y_ENSURE(NResource::FindExact("pg_am.dat", &amData));
+        TString collationData;
+        Y_ENSURE(NResource::FindExact("pg_collation.dat", &collationData));
         TString languagesData;
         Y_ENSURE(NResource::FindExact("pg_language.dat", &languagesData));
         THashMap<ui32, TLazyTypeInfo> lazyTypeInfos;
@@ -1860,6 +1926,22 @@ struct TCatalog: public IExtensionSqlBuilder {
         State->AmOps = ParseAmOps(amOpData, State->TypeByName, State->Types, State->OperatorsByName, State->Operators, State->OpFamilies);
         State->AmProcs = ParseAmProcs(amProcData, State->TypeByName, State->ProcByName, State->Procs, State->OpFamilies);
         State->Ams = ParseAms(amData);
+        State->Collations = ParseCollations(collationData);
+        for (const auto& [k, v] : State->Collations) {
+            Y_ENSURE(State->CollationByName.insert(std::make_pair(v.Name, k)).second);
+        }
+
+        for (size_t i = 0; i < Y_ARRAY_SIZE(AllIcuCollationLocalesRaw); ++i) {
+            TCollationDesc desc;
+            desc.Oid = IcuCollationOidBase + i;
+            desc.IcuLocale = AllIcuCollationLocalesRaw[i];
+            desc.Name = desc.IcuLocale + "-x-icu";
+            desc.Provider = ECollationProvider::Icu;
+            desc.Descr = "ICU locale collation";
+            Y_ENSURE(State->Collations.insert(std::make_pair(desc.Oid, desc)).second);
+            Y_ENSURE(State->CollationByName.insert(std::make_pair(desc.Name, desc.Oid)).second);
+        }
+
         State->Namespaces = FillNamespaces();
         for (auto& [k, v] : State->Types) {
             if (v.TypeId != v.ArrayTypeId) {
@@ -2263,6 +2345,7 @@ struct TCatalog: public IExtensionSqlBuilder {
         TCasts Casts;
         TAggregations Aggregations;
         TAms Ams;
+        TCollations Collations;
         TNamespaces Namespaces;
         TOpFamilies OpFamilies;
         TOpClasses OpClasses;
@@ -2272,6 +2355,7 @@ struct TCatalog: public IExtensionSqlBuilder {
         TLanguages Languages;
         THashMap<TString, TVector<ui32>> ProcByName;
         THashMap<TString, ui32> TypeByName;
+        THashMap<TString, ui32> CollationByName;
         THashMap<std::pair<ui32, ui32>, ui32> CastsByDir;
         THashMap<TString, TVector<ui32>> OperatorsByName;
         THashMap<TString, TVector<ui32>> AggregationsByName;
@@ -2463,6 +2547,38 @@ void EnumAm(std::function<void(ui32, const TAmDesc&)> f) {
     }
 }
 
+bool HasCollation(const TString& name) {
+    const auto& catalog = TCatalog::Instance();
+    return catalog.State->CollationByName.contains(name);
+}
+
+const TCollationDesc& LookupCollation(const TString& name) {
+    const auto& catalog = TCatalog::Instance();
+    const auto oidPtr = catalog.State->CollationByName.FindPtr(name);
+    if (!oidPtr) {
+        throw yexception() << "No such collation: " << name;
+    }
+
+    return LookupCollation(*oidPtr);
+}
+
+const TCollationDesc& LookupCollation(ui32 oid) {
+    const auto& catalog = TCatalog::Instance();
+    const auto descPtr = catalog.State->Collations.FindPtr(oid);
+    if (!descPtr) {
+        throw yexception() << "No such collation: " << oid;
+    }
+
+    return *descPtr;
+}
+
+void EnumCollation(std::function<void(ui32, const TCollationDesc&)> f) {
+    const auto& catalog = TCatalog::Instance();
+    for (const auto& [oid, desc] : catalog.State->Collations) {
+        f(oid, desc);
+    }
+}
+
 void EnumConversions(std::function<void(const TConversionDesc&)> f) {
     const auto& catalog = TCatalog::Instance();
     for (const auto& [_, desc] : catalog.State->Conversions) {
diff --git a/yql/essentials/parser/pg_catalog/catalog.h b/yql/essentials/parser/pg_catalog/catalog.h
index 1f30f692706..e06b7616d44 100644
--- a/yql/essentials/parser/pg_catalog/catalog.h
+++ b/yql/essentials/parser/pg_catalog/catalog.h
@@ -91,6 +91,32 @@ constexpr ui32 DefaultCollationOid = 100;
 constexpr ui32 C_CollationOid = 950;
 constexpr ui32 PosixCollationOid = 951;
 
+// Oid space reserved for ICU locale collations (name "<locale>-x-icu"), kept clear of the
+// oids used by pg_collation.dat (which top out in the low thousands).
+// A locale's oid is IcuCollationOidBase plus its position in the checked-in, append-only
+// pg_collation_icu.generated.h (see gen_icu_collations) - stable across processes/rebuilds
+// regardless of which ICU library version is actually linked, since it is our own versioned
+// data rather than something derived live from whatever ICU happens to be available.
+constexpr ui32 IcuCollationOidBase = 1'000'000;
+
+// Copied from pg_collation.h, COLLPROVIDER_* constants
+enum class ECollationProvider: char {
+    Default = 'd',
+    Icu = 'i',
+    Libc = 'c',
+};
+
+struct TCollationDesc {
+    ui32 Oid = 0;
+    TString Name;
+    TString Descr;
+    ECollationProvider Provider = ECollationProvider::Libc;
+    i32 Encoding = -1;
+    TString Collate;
+    TString Ctype;
+    TString IcuLocale;
+};
+
 // Copied from pg_type_d.h, TYPTYPE_* constants
 enum class ETypType: char {
     Base = 'b',
@@ -295,6 +321,11 @@ void EnumTypes(std::function<void(ui32, const TTypeDesc&)> f);
 const TAmDesc& LookupAm(ui32 oid);
 void EnumAm(std::function<void(ui32, const TAmDesc&)> f);
 
+bool HasCollation(const TString& name);
+const TCollationDesc& LookupCollation(const TString& name);
+const TCollationDesc& LookupCollation(ui32 oid);
+void EnumCollation(std::function<void(ui32, const TCollationDesc&)> f);
+
 void EnumConversions(std::function<void(const TConversionDesc&)> f);
 
 const TNamespaceDesc& LookupNamespace(ui32 oid);
@@ -497,6 +528,11 @@ inline void Out<NYql::NPg::ECoercionCode>(IOutputStream& out, NYql::NPg::ECoerci
 }
 
 template <>
+inline void Out<NYql::NPg::ECollationProvider>(IOutputStream& out, NYql::NPg::ECollationProvider value) {
+    out.Write(static_cast<std::underlying_type<NYql::NPg::ECollationProvider>::type>(value));
+}
+
+template <>
 struct THash<NYql::NPg::TTableInfoKey> {
     size_t operator()(const NYql::NPg::TTableInfoKey& val) const {
         return val.Hash();
diff --git a/yql/essentials/parser/pg_catalog/gen_icu_collations/main.cpp b/yql/essentials/parser/pg_catalog/gen_icu_collations/main.cpp
new file mode 100644
index 00000000000..9d9e4577806
--- /dev/null
+++ b/yql/essentials/parser/pg_catalog/gen_icu_collations/main.cpp
@@ -0,0 +1,107 @@
+// Regenerates pg_collation_icu.generated.h - the checked-in list of ICU collation locale
+// names known to pg_catalog. Run manually and commit the result whenever the vendored ICU
+// (contrib/libs/icu) is updated:
+//
+//   ya make yql/essentials/parser/pg_catalog/gen_icu_collations
+//   yql/essentials/parser/pg_catalog/gen_icu_collations/gen_icu_collations \
+//       yql/essentials/parser/pg_catalog/pg_collation_icu.generated.h
+//
+// The output is append-only: existing entries are read back first and kept in place, and
+// only locales not already present are appended at the end. This keeps each locale's
+// position in the file - and hence the collation oid pg_catalog derives from that position
+// - stable across regenerations, even if the set of locales ICU knows about changes,
+// exactly like AllStaticTablesRaw/pg_class.generated.h and library/cpp/type_info/tz do for
+// their own generated tables.
+
+#include <unicode/uloc.h>
+
+#include <util/generic/algorithm.h>
+#include <util/generic/hash_set.h>
+#include <util/generic/string.h>
+#include <util/generic/vector.h>
+#include <util/generic/yexception.h>
+#include <util/stream/file.h>
+#include <util/system/fs.h>
+
+#include <cstdio>
+
+namespace {
+
+// Canonicalizes an ICU locale id (e.g. "de_DE") to its BCP47 language tag (e.g. "de-DE").
+// Returns an empty string if ICU can't parse it at all.
+TString CanonicalizeIcuLocale(const TString& locale) {
+    UErrorCode status = U_ZERO_ERROR;
+    std::array<char, ULOC_FULLNAME_CAPACITY> tag;
+    auto len = uloc_toLanguageTag(locale.c_str(), tag.data(), tag.size(), /* strict */ true, &status);
+    if (U_FAILURE(status)) {
+        return {};
+    }
+
+    return TString(tag.data(), len);
+}
+
+TVector<TString> ReadExistingLocales(const TString& path) {
+    TVector<TString> result;
+    if (!NFs::Exists(path)) {
+        return result;
+    }
+
+    TFileInput input(path);
+    TString line;
+    while (input.ReadLine(line)) {
+        auto endQuote = line.find('"', 1);
+        Y_ENSURE(line.size() > 2 && line[0] == '"' && endQuote != TString::npos, "Malformed line in " << path << ": " << line);
+        result.push_back(line.substr(1, endQuote - 1));
+    }
+
+    return result;
+}
+
+TVector<TString> DiscoverIcuLocales() {
+    TVector<TString> result;
+    if (auto root = CanonicalizeIcuLocale(""); !root.empty()) {
+        result.push_back(root);
+    }
+
+    for (i32 i = 0; i < uloc_countAvailable(); ++i) {
+        if (auto tag = CanonicalizeIcuLocale(uloc_getAvailable(i)); !tag.empty()) {
+            result.push_back(tag);
+        }
+    }
+
+    Sort(result.begin(), result.end());
+    result.erase(Unique(result.begin(), result.end()), result.end());
+    return result;
+}
+
+} // namespace
+
+int main(int argc, char** argv) {
+    Y_ENSURE(argc == 2, "usage: gen_icu_collations <path-to-pg_collation_icu.generated.h>");
+    TString outputPath = argv[1];
+
+    auto existing = ReadExistingLocales(outputPath);
+    THashSet<TString> seen(existing.begin(), existing.end());
+
+    TVector<TString> toAppend;
+    for (auto& tag : DiscoverIcuLocales()) {
+        if (seen.insert(tag).second) {
+            toAppend.push_back(tag);
+        }
+    }
+
+    {
+        TFileOutput output(outputPath);
+        for (auto& tag : existing) {
+            output << "\"" << tag << "\",\n";
+        }
+
+        for (auto& tag : toAppend) {
+            output << "\"" << tag << "\",\n";
+        }
+    }
+
+    Cerr << "Wrote " << (existing.size() + toAppend.size()) << " ICU collation locales ("
+         << toAppend.size() << " new) to " << outputPath << Endl;
+    return 0;
+}
diff --git a/yql/essentials/parser/pg_catalog/gen_icu_collations/ya.make b/yql/essentials/parser/pg_catalog/gen_icu_collations/ya.make
new file mode 100644
index 00000000000..b90c170c01a
--- /dev/null
+++ b/yql/essentials/parser/pg_catalog/gen_icu_collations/ya.make
@@ -0,0 +1,11 @@
+PROGRAM(gen_icu_collations)
+
+SRCS(
+    main.cpp
+)
+
+PEERDIR(
+    contrib/libs/icu
+)
+
+END()
diff --git a/yql/essentials/parser/pg_catalog/pg_collation_icu.generated.h b/yql/essentials/parser/pg_catalog/pg_collation_icu.generated.h
new file mode 100644
index 00000000000..c1796fc4a7f
--- /dev/null
+++ b/yql/essentials/parser/pg_catalog/pg_collation_icu.generated.h
@@ -0,0 +1,907 @@
+"af",
+"af-NA",
+"af-ZA",
+"agq",
+"agq-CM",
+"ak",
+"ak-GH",
+"am",
+"am-ET",
+"ar",
+"ar-001",
+"ar-AE",
+"ar-BH",
+"ar-DJ",
+"ar-DZ",
+"ar-EG",
+"ar-EH",
+"ar-ER",
+"ar-IL",
+"ar-IQ",
+"ar-JO",
+"ar-KM",
+"ar-KW",
+"ar-LB",
+"ar-LY",
+"ar-MA",
+"ar-MR",
+"ar-OM",
+"ar-PS",
+"ar-QA",
+"ar-SA",
+"ar-SD",
+"ar-SO",
+"ar-SS",
+"ar-SY",
+"ar-TD",
+"ar-TN",
+"ar-YE",
+"as",
+"as-IN",
+"asa",
+"asa-TZ",
+"ast",
+"ast-ES",
+"az",
+"az-Cyrl",
+"az-Cyrl-AZ",
+"az-Latn",
+"az-Latn-AZ",
+"ba",
+"ba-RU",
+"bas",
+"bas-CM",
+"be",
+"be-BY",
+"bem",
+"bem-ZM",
+"bez",
+"bez-TZ",
+"bg",
+"bg-BG",
+"bgc",
+"bgc-IN",
+"bho",
+"bho-IN",
+"blo",
+"blo-BJ",
+"bm",
+"bm-ML",
+"bn",
+"bn-BD",
+"bn-IN",
+"bo",
+"bo-CN",
+"bo-IN",
+"br",
+"br-FR",
+"brx",
+"brx-IN",
+"bs",
+"bs-Cyrl",
+"bs-Cyrl-BA",
+"bs-Latn",
+"bs-Latn-BA",
+"bua",
+"bua-RU",
+"ca",
+"ca-AD",
+"ca-ES",
+"ca-FR",
+"ca-IT",
+"ccp",
+"ccp-BD",
+"ccp-IN",
+"ce",
+"ce-RU",
+"ceb",
+"ceb-PH",
+"cgg",
+"cgg-UG",
+"chr",
+"chr-US",
+"ckb",
+"ckb-IQ",
+"ckb-IR",
+"cs",
+"cs-CZ",
+"csw",
+"csw-CA",
+"cv",
+"cv-RU",
+"cy",
+"cy-GB",
+"da",
+"da-DK",
+"da-GL",
+"dav",
+"dav-KE",
+"de",
+"de-AT",
+"de-BE",
+"de-CH",
+"de-DE",
+"de-IT",
+"de-LI",
+"de-LU",
+"dje",
+"dje-NE",
+"doi",
+"doi-IN",
+"dsb",
+"dsb-DE",
+"dua",
+"dua-CM",
+"dyo",
+"dyo-SN",
+"dz",
+"dz-BT",
+"ebu",
+"ebu-KE",
+"ee",
+"ee-GH",
+"ee-TG",
+"el",
+"el-CY",
+"el-GR",
+"en",
+"en-001",
+"en-150",
+"en-AE",
+"en-AG",
+"en-AI",
+"en-AS",
+"en-AT",
+"en-AU",
+"en-BB",
+"en-BE",
+"en-BI",
+"en-BM",
+"en-BS",
+"en-BW",
+"en-BZ",
+"en-CA",
+"en-CC",
+"en-CH",
+"en-CK",
+"en-CM",
+"en-CX",
+"en-CY",
+"en-CZ",
+"en-DE",
+"en-DG",
+"en-DK",
+"en-DM",
+"en-EE",
+"en-ER",
+"en-ES",
+"en-FI",
+"en-FJ",
+"en-FK",
+"en-FM",
+"en-FR",
+"en-GB",
+"en-GD",
+"en-GE",
+"en-GG",
+"en-GH",
+"en-GI",
+"en-GM",
+"en-GS",
+"en-GU",
+"en-GY",
+"en-HK",
+"en-HU",
+"en-ID",
+"en-IE",
+"en-IL",
+"en-IM",
+"en-IN",
+"en-IO",
+"en-IT",
+"en-JE",
+"en-JM",
+"en-JP",
+"en-KE",
+"en-KI",
+"en-KN",
+"en-KY",
+"en-LC",
+"en-LR",
+"en-LS",
+"en-LT",
+"en-LV",
+"en-MG",
+"en-MH",
+"en-MO",
+"en-MP",
+"en-MS",
+"en-MT",
+"en-MU",
+"en-MV",
+"en-MW",
+"en-MY",
+"en-NA",
+"en-NF",
+"en-NG",
+"en-NL",
+"en-NO",
+"en-NR",
+"en-NU",
+"en-NZ",
+"en-PG",
+"en-PH",
+"en-PK",
+"en-PL",
+"en-PN",
+"en-PR",
+"en-PT",
+"en-PW",
+"en-RO",
+"en-RW",
+"en-SB",
+"en-SC",
+"en-SD",
+"en-SE",
+"en-SG",
+"en-SH",
+"en-SI",
+"en-SK",
+"en-SL",
+"en-SS",
+"en-SX",
+"en-SZ",
+"en-TC",
+"en-TK",
+"en-TO",
+"en-TT",
+"en-TV",
+"en-TZ",
+"en-UA",
+"en-UG",
+"en-UM",
+"en-US",
+"en-US-u-va-posix",
+"en-VC",
+"en-VG",
+"en-VI",
+"en-VU",
+"en-WS",
+"en-ZA",
+"en-ZM",
+"en-ZW",
+"eo",
+"eo-001",
+"es",
+"es-419",
+"es-AR",
+"es-BO",
+"es-BR",
+"es-BZ",
+"es-CL",
+"es-CO",
+"es-CR",
+"es-CU",
+"es-DO",
+"es-EA",
+"es-EC",
+"es-ES",
+"es-GQ",
+"es-GT",
+"es-HN",
+"es-IC",
+"es-MX",
+"es-NI",
+"es-PA",
+"es-PE",
+"es-PH",
+"es-PR",
+"es-PY",
+"es-SV",
+"es-US",
+"es-UY",
+"es-VE",
+"et",
+"et-EE",
+"eu",
+"eu-ES",
+"ewo",
+"ewo-CM",
+"fa",
+"fa-AF",
+"fa-IR",
+"ff",
+"ff-Adlm",
+"ff-Adlm-BF",
+"ff-Adlm-CM",
+"ff-Adlm-GH",
+"ff-Adlm-GM",
+"ff-Adlm-GN",
+"ff-Adlm-GW",
+"ff-Adlm-LR",
+"ff-Adlm-MR",
+"ff-Adlm-NE",
+"ff-Adlm-NG",
+"ff-Adlm-SL",
+"ff-Adlm-SN",
+"ff-Latn",
+"ff-Latn-BF",
+"ff-Latn-CM",
+"ff-Latn-GH",
+"ff-Latn-GM",
+"ff-Latn-GN",
+"ff-Latn-GW",
+"ff-Latn-LR",
+"ff-Latn-MR",
+"ff-Latn-NE",
+"ff-Latn-NG",
+"ff-Latn-SL",
+"ff-Latn-SN",
+"fi",
+"fi-FI",
+"fil",
+"fil-PH",
+"fo",
+"fo-DK",
+"fo-FO",
+"fr",
+"fr-BE",
+"fr-BF",
+"fr-BI",
+"fr-BJ",
+"fr-BL",
+"fr-CA",
+"fr-CD",
+"fr-CF",
+"fr-CG",
+"fr-CH",
+"fr-CI",
+"fr-CM",
+"fr-DJ",
+"fr-DZ",
+"fr-FR",
+"fr-GA",
+"fr-GF",
+"fr-GN",
+"fr-GP",
+"fr-GQ",
+"fr-HT",
+"fr-KM",
+"fr-LU",
+"fr-MA",
+"fr-MC",
+"fr-MF",
+"fr-MG",
+"fr-ML",
+"fr-MQ",
+"fr-MR",
+"fr-MU",
+"fr-NC",
+"fr-NE",
+"fr-PF",
+"fr-PM",
+"fr-RE",
+"fr-RW",
+"fr-SC",
+"fr-SN",
+"fr-SY",
+"fr-TD",
+"fr-TG",
+"fr-TN",
+"fr-VU",
+"fr-WF",
+"fr-YT",
+"fur",
+"fur-IT",
+"fy",
+"fy-NL",
+"ga",
+"ga-GB",
+"ga-IE",
+"gaa",
+"gaa-GH",
+"gd",
+"gd-GB",
+"gl",
+"gl-ES",
+"gsw",
+"gsw-CH",
+"gsw-FR",
+"gsw-LI",
+"gu",
+"gu-IN",
+"guz",
+"guz-KE",
+"gv",
+"gv-IM",
+"ha",
+"ha-GH",
+"ha-NE",
+"ha-NG",
+"haw",
+"haw-US",
+"he",
+"he-IL",
+"hi",
+"hi-IN",
+"hi-Latn",
+"hi-Latn-IN",
+"hr",
+"hr-BA",
+"hr-HR",
+"hsb",
+"hsb-DE",
+"hu",
+"hu-HU",
+"hy",
+"hy-AM",
+"ia",
+"ia-001",
+"id",
+"id-ID",
+"ie",
+"ie-EE",
+"ig",
+"ig-NG",
+"ii",
+"ii-CN",
+"is",
+"is-IS",
+"it",
+"it-CH",
+"it-IT",
+"it-SM",
+"it-VA",
+"ja",
+"ja-JP",
+"jgo",
+"jgo-CM",
+"jmc",
+"jmc-TZ",
+"jv",
+"jv-ID",
+"ka",
+"ka-GE",
+"kab",
+"kab-DZ",
+"kam",
+"kam-KE",
+"kde",
+"kde-TZ",
+"kea",
+"kea-CV",
+"kgp",
+"kgp-BR",
+"khq",
+"khq-ML",
+"ki",
+"ki-KE",
+"kk",
+"kk-Arab",
+"kk-Arab-CN",
+"kk-Cyrl",
+"kk-Cyrl-KZ",
+"kk-KZ",
+"kkj",
+"kkj-CM",
+"kl",
+"kl-GL",
+"kln",
+"kln-KE",
+"km",
+"km-KH",
+"kn",
+"kn-IN",
+"ko",
+"ko-CN",
+"ko-KP",
+"ko-KR",
+"kok",
+"kok-Deva",
+"kok-Deva-IN",
+"kok-Latn",
+"kok-Latn-IN",
+"ks",
+"ks-Arab",
+"ks-Arab-IN",
+"ks-Deva",
+"ks-Deva-IN",
+"ksb",
+"ksb-TZ",
+"ksf",
+"ksf-CM",
+"ksh",
+"ksh-DE",
+"ku",
+"ku-Latn",
+"ku-Latn-IQ",
+"ku-Latn-SY",
+"ku-Latn-TR",
+"ku-TR",
+"kw",
+"kw-GB",
+"kxv",
+"kxv-Deva",
+"kxv-Deva-IN",
+"kxv-Latn",
+"kxv-Latn-IN",
+"kxv-Orya",
+"kxv-Orya-IN",
+"kxv-Telu",
+"kxv-Telu-IN",
+"ky",
+"ky-KG",
+"lag",
+"lag-TZ",
+"lb",
+"lb-LU",
+"lg",
+"lg-UG",
+"lij",
+"lij-IT",
+"lkt",
+"lkt-US",
+"lmo",
+"lmo-IT",
+"ln",
+"ln-AO",
+"ln-CD",
+"ln-CF",
+"ln-CG",
+"lo",
+"lo-LA",
+"lrc",
+"lrc-IQ",
+"lrc-IR",
+"lt",
+"lt-LT",
+"lu",
+"lu-CD",
+"luo",
+"luo-KE",
+"luy",
+"luy-KE",
+"lv",
+"lv-LV",
+"mai",
+"mai-IN",
+"mas",
+"mas-KE",
+"mas-TZ",
+"mer",
+"mer-KE",
+"mfe",
+"mfe-MU",
+"mg",
+"mg-MG",
+"mgh",
+"mgh-MZ",
+"mgo",
+"mgo-CM",
+"mi",
+"mi-NZ",
+"mk",
+"mk-MK",
+"ml",
+"ml-IN",
+"mn",
+"mn-MN",
+"mni",
+"mni-Beng",
+"mni-Beng-IN",
+"mr",
+"mr-IN",
+"ms",
+"ms-BN",
+"ms-ID",
+"ms-MY",
+"ms-SG",
+"mt",
+"mt-MT",
+"mua",
+"mua-CM",
+"my",
+"my-MM",
+"mzn",
+"mzn-IR",
+"naq",
+"naq-NA",
+"nb",
+"nb-NO",
+"nb-SJ",
+"nd",
+"nd-ZW",
+"nds",
+"nds-DE",
+"nds-NL",
+"ne",
+"ne-IN",
+"ne-NP",
+"nl",
+"nl-AW",
+"nl-BE",
+"nl-BQ",
+"nl-CW",
+"nl-NL",
+"nl-SR",
+"nl-SX",
+"nmg",
+"nmg-CM",
+"nn",
+"nn-NO",
+"nnh",
+"nnh-CM",
+"no",
+"nqo",
+"nqo-GN",
+"nso",
+"nso-ZA",
+"nus",
+"nus-SS",
+"nyn",
+"nyn-UG",
+"oc",
+"oc-ES",
+"oc-FR",
+"om",
+"om-ET",
+"om-KE",
+"or",
+"or-IN",
+"os",
+"os-GE",
+"os-RU",
+"pa",
+"pa-Arab",
+"pa-Arab-PK",
+"pa-Guru",
+"pa-Guru-IN",
+"pcm",
+"pcm-NG",
+"pl",
+"pl-PL",
+"pms",
+"pms-IT",
+"prg",
+"prg-PL",
+"ps",
+"ps-AF",
+"ps-PK",
+"pt",
+"pt-AO",
+"pt-BR",
+"pt-CH",
+"pt-CV",
+"pt-GQ",
+"pt-GW",
+"pt-LU",
+"pt-MO",
+"pt-MZ",
+"pt-PT",
+"pt-ST",
+"pt-TL",
+"qu",
+"qu-BO",
+"qu-EC",
+"qu-PE",
+"raj",
+"raj-IN",
+"rm",
+"rm-CH",
+"rn",
+"rn-BI",
+"ro",
+"ro-MD",
+"ro-RO",
+"rof",
+"rof-TZ",
+"ru",
+"ru-BY",
+"ru-KG",
+"ru-KZ",
+"ru-MD",
+"ru-RU",
+"ru-UA",
+"rw",
+"rw-RW",
+"rwk",
+"rwk-TZ",
+"sa",
+"sa-IN",
+"sah",
+"sah-RU",
+"saq",
+"saq-KE",
+"sat",
+"sat-Olck",
+"sat-Olck-IN",
+"sbp",
+"sbp-TZ",
+"sc",
+"sc-IT",
+"scn",
+"scn-IT",
+"sd",
+"sd-Arab",
+"sd-Arab-PK",
+"sd-Deva",
+"sd-Deva-IN",
+"se",
+"se-FI",
+"se-NO",
+"se-SE",
+"seh",
+"seh-MZ",
+"ses",
+"ses-ML",
+"sg",
+"sg-CF",
+"shi",
+"shi-Latn",
+"shi-Latn-MA",
+"shi-Tfng",
+"shi-Tfng-MA",
+"shn",
+"shn-MM",
+"shn-TH",
+"si",
+"si-LK",
+"sk",
+"sk-SK",
+"sl",
+"sl-SI",
+"smn",
+"smn-FI",
+"sn",
+"sn-ZW",
+"so",
+"so-DJ",
+"so-ET",
+"so-KE",
+"so-SO",
+"sq",
+"sq-AL",
+"sq-MK",
+"sq-XK",
+"sr",
+"sr-Cyrl",
+"sr-Cyrl-BA",
+"sr-Cyrl-ME",
+"sr-Cyrl-RS",
+"sr-Cyrl-XK",
+"sr-Latn",
+"sr-Latn-BA",
+"sr-Latn-ME",
+"sr-Latn-RS",
+"sr-Latn-XK",
+"st",
+"st-LS",
+"st-ZA",
+"su",
+"su-Latn",
+"su-Latn-ID",
+"sv",
+"sv-AX",
+"sv-FI",
+"sv-SE",
+"sw",
+"sw-CD",
+"sw-KE",
+"sw-TZ",
+"sw-UG",
+"syr",
+"syr-IQ",
+"syr-SY",
+"szl",
+"szl-PL",
+"ta",
+"ta-IN",
+"ta-LK",
+"ta-MY",
+"ta-SG",
+"te",
+"te-IN",
+"teo",
+"teo-KE",
+"teo-UG",
+"tg",
+"tg-TJ",
+"th",
+"th-TH",
+"ti",
+"ti-ER",
+"ti-ET",
+"tk",
+"tk-TM",
+"tn",
+"tn-BW",
+"tn-ZA",
+"to",
+"to-TO",
+"tok",
+"tok-001",
+"tr",
+"tr-CY",
+"tr-TR",
+"tt",
+"tt-RU",
+"twq",
+"twq-NE",
+"tyv",
+"tyv-RU",
+"tzm",
+"tzm-MA",
+"ug",
+"ug-CN",
+"uk",
+"uk-UA",
+"und",
+"ur",
+"ur-IN",
+"ur-PK",
+"uz",
+"uz-Arab",
+"uz-Arab-AF",
+"uz-Cyrl",
+"uz-Cyrl-UZ",
+"uz-Latn",
+"uz-Latn-UZ",
+"vai",
+"vai-Latn",
+"vai-Latn-LR",
+"vai-Vaii",
+"vai-Vaii-LR",
+"vec",
+"vec-IT",
+"vi",
+"vi-VN",
+"vmw",
+"vmw-MZ",
+"vun",
+"vun-TZ",
+"wae",
+"wae-CH",
+"wo",
+"wo-SN",
+"xh",
+"xh-ZA",
+"xnr",
+"xnr-IN",
+"xog",
+"xog-UG",
+"yav",
+"yav-CM",
+"yi",
+"yi-UA",
+"yo",
+"yo-BJ",
+"yo-NG",
+"yrl",
+"yrl-BR",
+"yrl-CO",
+"yrl-VE",
+"yue",
+"yue-Hans",
+"yue-Hans-CN",
+"yue-Hant",
+"yue-Hant-CN",
+"yue-Hant-HK",
+"yue-Hant-MO",
+"za",
+"za-CN",
+"zgh",
+"zgh-MA",
+"zh",
+"zh-Hans",
+"zh-Hans-CN",
+"zh-Hans-HK",
+"zh-Hans-MO",
+"zh-Hans-MY",
+"zh-Hans-SG",
+"zh-Hant",
+"zh-Hant-HK",
+"zh-Hant-MO",
+"zh-Hant-MY",
+"zh-Hant-TW",
+"zu",
+"zu-ZA",
diff --git a/yql/essentials/parser/pg_catalog/ut/catalog_ut.cpp b/yql/essentials/parser/pg_catalog/ut/catalog_ut.cpp
index 0dd8e623c14..1bc9f4bf3cd 100644
--- a/yql/essentials/parser/pg_catalog/ut/catalog_ut.cpp
+++ b/yql/essentials/parser/pg_catalog/ut/catalog_ut.cpp
@@ -207,3 +207,69 @@ Y_UNIT_TEST(TestOk) {
     UNIT_ASSERT_VALUES_EQUAL(LookupProc(procId).Name, "iso8859_1_to_utf8");
 }
 } // Y_UNIT_TEST_SUITE(TConversionTests)
+
+Y_UNIT_TEST_SUITE(TCollationTests) {
+Y_UNIT_TEST(TestMissing) {
+    UNIT_ASSERT(!HasCollation("_foo_bar_"));
+    UNIT_ASSERT_EXCEPTION(LookupCollation("_foo_bar_"), yexception);
+    UNIT_ASSERT_EXCEPTION(LookupCollation((ui32)123456), yexception);
+}
+
+Y_UNIT_TEST(TestDefault) {
+    UNIT_ASSERT(HasCollation("default"));
+    const auto& ret = LookupCollation("default");
+    UNIT_ASSERT_VALUES_EQUAL(ret.Oid, DefaultCollationOid);
+    UNIT_ASSERT_VALUES_EQUAL(ret.Provider, ECollationProvider::Default);
+    UNIT_ASSERT_VALUES_EQUAL(LookupCollation(ret.Oid).Name, "default");
+}
+
+Y_UNIT_TEST(TestC) {
+    const auto& ret = LookupCollation("C");
+    UNIT_ASSERT_VALUES_EQUAL(ret.Oid, C_CollationOid);
+    UNIT_ASSERT_VALUES_EQUAL(ret.Provider, ECollationProvider::Libc);
+    UNIT_ASSERT_VALUES_EQUAL(ret.Collate, "C");
+    UNIT_ASSERT_VALUES_EQUAL(ret.Ctype, "C");
+}
+
+Y_UNIT_TEST(TestPosix) {
+    const auto& ret = LookupCollation("POSIX");
+    UNIT_ASSERT_VALUES_EQUAL(ret.Oid, PosixCollationOid);
+    UNIT_ASSERT_VALUES_EQUAL(ret.Provider, ECollationProvider::Libc);
+}
+
+Y_UNIT_TEST(TestUnicodeIcu) {
+    const auto& ret = LookupCollation("unicode");
+    UNIT_ASSERT_VALUES_EQUAL(ret.Provider, ECollationProvider::Icu);
+    UNIT_ASSERT_VALUES_EQUAL(ret.IcuLocale, "und");
+}
+
+Y_UNIT_TEST(TestEnum) {
+    size_t count = 0;
+    EnumCollation([&](ui32 oid, const TCollationDesc& desc) {
+        UNIT_ASSERT_VALUES_EQUAL(LookupCollation(desc.Name).Oid, oid);
+        ++count;
+    });
+
+    // 5 statically catalogued (pg_collation.dat) + generated ICU locale collations.
+    UNIT_ASSERT(count > 5);
+}
+
+Y_UNIT_TEST(TestIcuLocale) {
+    const auto& ret = LookupCollation("de-DE-x-icu");
+    UNIT_ASSERT_VALUES_EQUAL(ret.Provider, ECollationProvider::Icu);
+    UNIT_ASSERT_VALUES_EQUAL(ret.IcuLocale, "de-DE");
+    UNIT_ASSERT(ret.Oid >= IcuCollationOidBase);
+    UNIT_ASSERT_VALUES_EQUAL(LookupCollation(ret.Oid).Name, "de-DE-x-icu");
+
+    // The same locale always resolves to the same oid.
+    UNIT_ASSERT_VALUES_EQUAL(ret.Oid, LookupCollation("de-DE-x-icu").Oid);
+
+    // Different locales get different oids.
+    UNIT_ASSERT_UNEQUAL(ret.Oid, LookupCollation("en-US-x-icu").Oid);
+}
+
+Y_UNIT_TEST(TestIcuLocaleMissing) {
+    UNIT_ASSERT(!HasCollation("xx-XX-x-icu"));
+    UNIT_ASSERT_EXCEPTION(LookupCollation("xx-XX-x-icu"), yexception);
+}
+} // Y_UNIT_TEST_SUITE(TCollationTests)
diff --git a/yql/essentials/parser/pg_catalog/ya.make b/yql/essentials/parser/pg_catalog/ya.make
index f7eecb3e7a8..ab657f751dc 100644
--- a/yql/essentials/parser/pg_catalog/ya.make
+++ b/yql/essentials/parser/pg_catalog/ya.make
@@ -13,6 +13,7 @@ RESOURCE(../pg_wrapper/postgresql/src/include/catalog/pg_opclass.dat pg_opclass.
 RESOURCE(../pg_wrapper/postgresql/src/include/catalog/pg_amproc.dat pg_amproc.dat)
 RESOURCE(../pg_wrapper/postgresql/src/include/catalog/pg_amop.dat pg_amop.dat)
 RESOURCE(../pg_wrapper/postgresql/src/include/catalog/pg_am.dat pg_am.dat)
+RESOURCE(../pg_wrapper/postgresql/src/include/catalog/pg_collation.dat pg_collation.dat)
 RESOURCE(../pg_wrapper/postgresql/src/include/catalog/pg_conversion.dat pg_conversion.dat)
 RESOURCE(../pg_wrapper/postgresql/src/include/catalog/pg_language.dat pg_language.dat)
 RESOURCE(../pg_wrapper/postgresql/src/backend/catalog/system_functions.sql system_functions.sql)
@@ -31,6 +32,10 @@ PEERDIR(
 
 END()
 
+RECURSE(
+    gen_icu_collations
+)
+
 RECURSE_FOR_TESTS(
    ut
 )
diff --git a/yql/essentials/parser/pg_wrapper/comp_factory.cpp b/yql/essentials/parser/pg_wrapper/comp_factory.cpp
index 78b7e4c59fa..27601a078b3 100644
--- a/yql/essentials/parser/pg_wrapper/comp_factory.cpp
+++ b/yql/essentials/parser/pg_wrapper/comp_factory.cpp
@@ -463,6 +463,21 @@ public:
                 };
 
                 ApplyFillers(AllPgExtensionFillers, Y_ARRAY_SIZE(AllPgExtensionFillers), PgExtensionFillers_);
+            } else if (Table_ == "pg_collation") {
+                static const std::pair<const char*, TPgCollationFiller> AllPgCollationFillers[] = {
+                    {"oid", [](const NPg::TCollationDesc& desc) { return ScalarDatumToPod(ObjectIdGetDatum(desc.Oid)); }},
+                    {"collname", [](const NPg::TCollationDesc& desc) { return PointerDatumToPod((Datum)MakeFixedString(desc.Name, NAMEDATALEN)); }},
+                    {"collnamespace", [](const NPg::TCollationDesc&) { return ScalarDatumToPod(ObjectIdGetDatum(PG_CATALOG_NAMESPACE)); }},
+                    {"collowner", [](const NPg::TCollationDesc&) { return ScalarDatumToPod(ObjectIdGetDatum(1)); }},
+                    {"collprovider", [](const NPg::TCollationDesc& desc) { return ScalarDatumToPod(CharGetDatum((char)desc.Provider)); }},
+                    {"collisdeterministic", [](const NPg::TCollationDesc&) { return ScalarDatumToPod(BoolGetDatum(true)); }},
+                    {"collencoding", [](const NPg::TCollationDesc& desc) { return ScalarDatumToPod(Int32GetDatum(desc.Encoding)); }},
+                    {"collcollate", [](const NPg::TCollationDesc& desc) { return desc.Collate.empty() ? NUdf::TUnboxedValuePod() : PointerDatumToPod((Datum)MakeVar(desc.Collate)); }},
+                    {"collctype", [](const NPg::TCollationDesc& desc) { return desc.Ctype.empty() ? NUdf::TUnboxedValuePod() : PointerDatumToPod((Datum)MakeVar(desc.Ctype)); }},
+                    {"colliculocale", [](const NPg::TCollationDesc& desc) { return desc.IcuLocale.empty() ? NUdf::TUnboxedValuePod() : PointerDatumToPod((Datum)MakeVar(desc.IcuLocale)); }},
+                };
+
+                ApplyFillers(AllPgCollationFillers, Y_ARRAY_SIZE(AllPgCollationFillers), PgCollationFillers_);
             }
         } else {
             if (Table_ == "tables") {
@@ -864,6 +879,19 @@ public:
                     sysFiller.Fill(items);
                     rows.emplace_back(row);
                 });
+            } else if (Table_ == "pg_collation") {
+                NPg::EnumCollation([&](ui32, const NPg::TCollationDesc& desc) {
+                    NUdf::TUnboxedValue* items;
+                    auto row = compCtx.HolderFactory.CreateDirectArrayHolder(PgCollationFillers_.size(), items);
+                    for (ui32 i = 0; i < PgCollationFillers_.size(); ++i) {
+                        if (PgCollationFillers_[i]) {
+                            items[i] = PgCollationFillers_[i](desc);
+                        }
+                    }
+
+                    sysFiller.Fill(items);
+                    rows.emplace_back(row);
+                });
             }
         } else {
             if (Table_ == "tables") {
@@ -952,6 +980,9 @@ private:
     using TPgProcFiller = NUdf::TUnboxedValuePod(*)(const NPg::TProcDesc&);
     TVector<TPgProcFiller> PgProcFillers_;
 
+    using TPgCollationFiller = NUdf::TUnboxedValuePod(*)(const NPg::TCollationDesc&);
+    TVector<TPgCollationFiller> PgCollationFillers_;
+
     using TPgAggregateFiller = NUdf::TUnboxedValuePod(*)(const NPg::TAggregateDesc&);
     TVector<TPgAggregateFiller> PgAggregateFillers_;
 
@@ -1033,8 +1064,8 @@ private:
 };
 
 struct TPgResolvedCallNodeState : public TPgResolvedCallState, public TComputationValue<TPgResolvedCallNodeState> {
-    TPgResolvedCallNodeState(TMemoryUsageInfo* memInfo, ui32 numArgs, const FmgrInfo* finfo)
-        : TPgResolvedCallState(numArgs, finfo)
+    TPgResolvedCallNodeState(TMemoryUsageInfo* memInfo, ui32 numArgs, const FmgrInfo* finfo, ui32 collationOid)
+        : TPgResolvedCallState(numArgs, finfo, collationOid)
         , TComputationValue(memInfo) {}
 };
 
@@ -1043,10 +1074,11 @@ class TPgResolvedCallNode : public TPgResolvedCall<UseContext>, public TMutableC
     typedef TMutableComputationNode<TPgResolvedCallNode<UseContext>> TBaseComputation;
 public:
     TPgResolvedCallNode(TComputationMutables& mutables, const std::string_view& name, ui32 id,
-        TComputationNodePtrVector&& argNodes, TVector<TType*>&& argTypes, TType* returnType)
+        TComputationNodePtrVector&& argNodes, TVector<TType*>&& argTypes, TType* returnType, ui32 collationOid)
         : TPgResolvedCall<UseContext>(name, id, std::move(argTypes), returnType)
         , TBaseComputation(mutables)
         , ArgNodes(std::move(argNodes))
+        , CollationOid(collationOid)
         , StateIndex(mutables.CurValueIndex++)
     {
         Y_ENSURE(ArgNodes.size() == this->ArgDesc.size());
@@ -1068,13 +1100,14 @@ private:
     TPgResolvedCallNodeState& GetState(TComputationContext& compCtx) const {
         auto& result = compCtx.MutableValues[this->StateIndex];
         if (!result.HasValue()) {
-            result = compCtx.HolderFactory.Create<TPgResolvedCallNodeState>(this->ArgNodes.size(), &this->FInfo);
+            result = compCtx.HolderFactory.Create<TPgResolvedCallNodeState>(this->ArgNodes.size(), &this->FInfo, CollationOid);
         }
 
         return *static_cast<TPgResolvedCallNodeState*>(result.AsBoxed().Get());
     }
 
     const TComputationNodePtrVector ArgNodes;
+    const ui32 CollationOid;
     const ui32 StateIndex;
 };
 
@@ -1087,14 +1120,14 @@ private:
         public:
             TIterator(TMemoryUsageInfo* memInfo, const std::string_view& name, const TUnboxedValueVector& args,
                 const TVector<NPg::TTypeDesc>& argDesc, const NPg::TTypeDesc& retTypeDesc, const NPg::TProcDesc& procDesc,
-                const FmgrInfo* fInfo, const TStructType* structType, const TVector<NPg::TTypeDesc>& structTypeDesc, const THolderFactory& holderFactory)
+                const FmgrInfo* fInfo, ui32 collationOid, const TStructType* structType, const TVector<NPg::TTypeDesc>& structTypeDesc, const THolderFactory& holderFactory)
                 : TComputationValue<TIterator>(memInfo)
                 , Name(name)
                 , Args(args)
                 , ArgDesc(argDesc)
                 , RetTypeDesc(retTypeDesc)
                 , ProcDesc(procDesc)
-                , CallInfo(argDesc.size(), fInfo)
+                , CallInfo(argDesc.size(), fInfo, collationOid)
                 , StructType(structType)
                 , StructTypeDesc(structTypeDesc)
                 , HolderFactory(holderFactory)
@@ -1302,7 +1335,7 @@ private:
 
         TListValue(TMemoryUsageInfo* memInfo, TComputationContext& compCtx,
             const std::string_view& name, TUnboxedValueVector&& args, const TVector<NPg::TTypeDesc>& argDesc,
-            const NPg::TTypeDesc& retTypeDesc, const NPg::TProcDesc& procDesc, const FmgrInfo* fInfo,
+            const NPg::TTypeDesc& retTypeDesc, const NPg::TProcDesc& procDesc, const FmgrInfo* fInfo, ui32 collationOid,
             const TStructType* structType, const TVector<NPg::TTypeDesc>& structTypeDesc, const THolderFactory& /*holderFactory*/)
             : TCustomListValue(memInfo)
             , CompCtx(compCtx)
@@ -1312,6 +1345,7 @@ private:
             , RetTypeDesc(retTypeDesc)
             , ProcDesc(procDesc)
             , FInfo(fInfo)
+            , CollationOid(collationOid)
             , StructType(structType)
             , StructTypeDesc(structTypeDesc)
         {
@@ -1319,7 +1353,7 @@ private:
 
     private:
         NUdf::TUnboxedValue GetListIterator() const final {
-            return CompCtx.HolderFactory.Create<TIterator>(Name, Args, ArgDesc, RetTypeDesc, ProcDesc, FInfo, StructType, StructTypeDesc, CompCtx.HolderFactory);
+            return CompCtx.HolderFactory.Create<TIterator>(Name, Args, ArgDesc, RetTypeDesc, ProcDesc, FInfo, CollationOid, StructType, StructTypeDesc, CompCtx.HolderFactory);
         }
 
         TComputationContext& CompCtx;
@@ -1329,16 +1363,18 @@ private:
         const NPg::TTypeDesc& RetTypeDesc;
         const NPg::TProcDesc& ProcDesc;
         const FmgrInfo* FInfo;
+        const ui32 CollationOid;
         const TStructType* StructType;
         const TVector<NPg::TTypeDesc>& StructTypeDesc;
     };
 
 public:
     TPgResolvedMultiCall(TComputationMutables& mutables, const std::string_view& name, ui32 id,
-        TComputationNodePtrVector&& argNodes, TVector<TType*>&& argTypes, TType* returnType, const TStructType* structType)
+        TComputationNodePtrVector&& argNodes, TVector<TType*>&& argTypes, TType* returnType, const TStructType* structType, ui32 collationOid)
         : TPgResolvedCallBase(name, id, std::move(argTypes), returnType, true, structType)
         , TBaseComputation(mutables)
         , ArgNodes(std::move(argNodes))
+        , CollationOid(collationOid)
         , StructType(structType)
     {
         Y_ENSURE(ArgNodes.size() == ArgDesc.size());
@@ -1352,7 +1388,7 @@ public:
             args.push_back(value);
         }
 
-        return compCtx.HolderFactory.Create<TListValue>(compCtx, Name, std::move(args), ArgDesc, RetTypeDesc, ProcDesc, &FInfo, StructType, StructTypeDesc, compCtx.HolderFactory);
+        return compCtx.HolderFactory.Create<TListValue>(compCtx, Name, std::move(args), ArgDesc, RetTypeDesc, ProcDesc, &FInfo, CollationOid, StructType, StructTypeDesc, compCtx.HolderFactory);
     }
 
 private:
@@ -1362,6 +1398,7 @@ private:
         }
     }
     const TComputationNodePtrVector ArgNodes;
+    const ui32 CollationOid;
     const TStructType* StructType;
 };
 
@@ -2757,7 +2794,7 @@ std::shared_ptr<arrow::compute::ScalarKernel> MakeToPgKernel(TType* inputType, T
     return kernel;
 }
 
-std::shared_ptr<arrow::compute::ScalarKernel> MakePgKernel(TVector<TType*> argTypes, TType* resultType, TExecFunc execFunc, ui32 procId) {
+std::shared_ptr<arrow::compute::ScalarKernel> MakePgKernel(TVector<TType*> argTypes, TType* resultType, TExecFunc execFunc, ui32 procId, ui32 collationOid) {
     std::shared_ptr<arrow::DataType> returnArrowType;
     MKQL_ENSURE(ConvertArrowType(AS_TYPE(TBlockType, resultType)->GetItemType(), returnArrowType), "Unsupported arrow type");
     auto kernel = std::make_shared<arrow::compute::ScalarKernel>(ConvertToInputTypes(argTypes), ConvertToOutputType(resultType),
@@ -2778,14 +2815,14 @@ std::shared_ptr<arrow::compute::ScalarKernel> MakePgKernel(TVector<TType*> argTy
     }
 
     kernel->null_handling = arrow::compute::NullHandling::COMPUTED_NO_PREALLOCATE;
-    kernel->init = [procId, pgArgTypes](arrow::compute::KernelContext*, const arrow::compute::KernelInitArgs&) {
+    kernel->init = [procId, pgArgTypes, collationOid](arrow::compute::KernelContext*, const arrow::compute::KernelInitArgs&) {
         auto state = std::make_unique<TPgKernelState>();
         Zero(state->flinfo);
         GetPgFuncAddr(procId, state->flinfo);
         YQL_ENSURE(state->flinfo.fn_addr);
         state->resultinfo = nullptr;
         state->context = nullptr;
-        state->fncollation = DEFAULT_COLLATION_OID;
+        state->fncollation = collationOid ? collationOid : DEFAULT_COLLATION_OID;
         const auto& procDesc = NPg::LookupProc(procId);
         const auto& retTypeDesc = NPg::LookupType(procDesc.ResultType);
         state->Name = procDesc.Name;
@@ -2855,7 +2892,8 @@ TComputationNodeFactory GetPgFactory() {
                 return new TPgToRecord(ctx.Mutables, input, structType, std::move(members));
             }
 
-            if (name == "PgResolvedCall") {
+            if (name == "PgResolvedCall" || name == "PgResolvedCall2") {
+                const bool hasCollation = (name == "PgResolvedCall2");
                 const auto useContextData = AS_VALUE(TDataLiteral, callable.GetInput(0));
                 const auto rangeFunctionData = AS_VALUE(TDataLiteral, callable.GetInput(1));
                 const auto nameData = AS_VALUE(TDataLiteral, callable.GetInput(2));
@@ -2864,9 +2902,18 @@ TComputationNodeFactory GetPgFactory() {
                 auto rangeFunction = rangeFunctionData->AsValue().Get<bool>();
                 auto name = nameData->AsValue().AsStringRef();
                 auto id = idData->AsValue().Get<ui32>();
+
+                ui32 collationOid = 0;
+                ui32 argsStart = 4;
+                if (hasCollation) {
+                    const auto collationOidData = AS_VALUE(TDataLiteral, callable.GetInput(4));
+                    collationOid = collationOidData->AsValue().Get<ui32>();
+                    argsStart = 5;
+                }
+
                 TComputationNodePtrVector argNodes;
                 TVector<TType*> argTypes;
-                for (ui32 i = 4; i < callable.GetInputsCount(); ++i) {
+                for (ui32 i = argsStart; i < callable.GetInputsCount(); ++i) {
                     argNodes.emplace_back(LocateNode(ctx.NodeLocator, callable, i));
                     argTypes.emplace_back(callable.GetInput(i).GetStaticType());
                 }
@@ -2883,25 +2930,35 @@ TComputationNodeFactory GetPgFactory() {
 
                 if (isList) {
                     YQL_ENSURE(!useContext);
-                    return new TPgResolvedMultiCall(ctx.Mutables, name, id, std::move(argNodes), std::move(argTypes), itemType, structType);
+                    return new TPgResolvedMultiCall(ctx.Mutables, name, id, std::move(argNodes), std::move(argTypes), itemType, structType, collationOid);
                 } else {
                     YQL_ENSURE(!structType);
                     if (useContext) {
-                        return new TPgResolvedCallNode<true>(ctx.Mutables, name, id, std::move(argNodes), std::move(argTypes), returnType);
+                        return new TPgResolvedCallNode<true>(ctx.Mutables, name, id, std::move(argNodes), std::move(argTypes), returnType, collationOid);
                     } else {
-                        return new TPgResolvedCallNode<false>(ctx.Mutables, name, id, std::move(argNodes), std::move(argTypes), returnType);
+                        return new TPgResolvedCallNode<false>(ctx.Mutables, name, id, std::move(argNodes), std::move(argTypes), returnType, collationOid);
                     }
                 }
             }
 
-            if (name == "BlockPgResolvedCall") {
+            if (name == "BlockPgResolvedCall" || name == "BlockPgResolvedCall2") {
+                const bool hasCollation = (name == "BlockPgResolvedCall2");
                 const auto nameData = AS_VALUE(TDataLiteral, callable.GetInput(0));
                 const auto idData = AS_VALUE(TDataLiteral, callable.GetInput(1));
                 auto name = nameData->AsValue().AsStringRef();
                 auto id = idData->AsValue().Get<ui32>();
+
+                ui32 collationOid = 0;
+                ui32 argsStart = 2;
+                if (hasCollation) {
+                    const auto collationOidData = AS_VALUE(TDataLiteral, callable.GetInput(2));
+                    collationOid = collationOidData->AsValue().Get<ui32>();
+                    argsStart = 3;
+                }
+
                 TComputationNodePtrVector argNodes;
                 TVector<TType*> argTypes;
-                for (ui32 i = 2; i < callable.GetInputsCount(); ++i) {
+                for (ui32 i = argsStart; i < callable.GetInputsCount(); ++i) {
                     argNodes.emplace_back(LocateNode(ctx.NodeLocator, callable, i));
                     argTypes.emplace_back(callable.GetInput(i).GetStaticType());
                 }
@@ -2909,7 +2966,7 @@ TComputationNodeFactory GetPgFactory() {
                 auto returnType = callable.GetType()->GetReturnType();
                 auto execFunc = FindExec(id);
                 YQL_ENSURE(execFunc);
-                auto kernel = MakePgKernel(argTypes, returnType, execFunc, id);
+                auto kernel = MakePgKernel(argTypes, returnType, execFunc, id, collationOid);
                 return new TBlockFuncNode(ctx.Mutables, ctx.RuntimeSettings->DatumValidation.Get(), callable.GetType()->GetName(), std::move(argNodes), argTypes, returnType, *kernel, kernel);
             }
 
diff --git a/yql/essentials/parser/pg_wrapper/comp_factory_utils.cpp b/yql/essentials/parser/pg_wrapper/comp_factory_utils.cpp
index 06b75438043..309e03621ea 100644
--- a/yql/essentials/parser/pg_wrapper/comp_factory_utils.cpp
+++ b/yql/essentials/parser/pg_wrapper/comp_factory_utils.cpp
@@ -169,7 +169,7 @@ NUdf::TUnboxedValue TPgConst::ExtractConst(i32 typeMod) const {
     return AnyDatumToPod(ret, TypeDesc.PassByValue);
 }
 
-TFunctionCallInfo::TFunctionCallInfo(ui32 numArgs, const FmgrInfo* finfo)
+TFunctionCallInfo::TFunctionCallInfo(ui32 numArgs, const FmgrInfo* finfo, ui32 collationOid)
     : NumArgs(numArgs)
     , CopyFmgrInfo(*finfo)
 {
@@ -183,7 +183,7 @@ TFunctionCallInfo::TFunctionCallInfo(ui32 numArgs, const FmgrInfo* finfo)
     Zero(callInfo);
     callInfo.flinfo = &CopyFmgrInfo; // client may mutate fn_extra
     callInfo.nargs = NumArgs;
-    callInfo.fncollation = DEFAULT_COLLATION_OID;
+    callInfo.fncollation = collationOid ? collationOid : DEFAULT_COLLATION_OID;
 }
 
 FunctionCallInfoBaseData& TFunctionCallInfo::Ref() {
@@ -197,8 +197,8 @@ TFunctionCallInfo::~TFunctionCallInfo() {
     }
 }
 
-TPgResolvedCallState::TPgResolvedCallState(ui32 numArgs, const FmgrInfo* finfo)
-    : CallInfo(numArgs, finfo)
+TPgResolvedCallState::TPgResolvedCallState(ui32 numArgs, const FmgrInfo* finfo, ui32 collationOid)
+    : CallInfo(numArgs, finfo, collationOid)
     , Args(numArgs)
 {
 }
@@ -248,7 +248,7 @@ NUdf::TUnboxedValue TPgResolvedCall<UseContext>::CallFunction(TPgResolvedCallSta
 
 template <bool UseContext>
 THolder<TPgResolvedCallState> TPgResolvedCall<UseContext>::CreateState() const {
-    return MakeHolder<TPgResolvedCallState>(GetArgCount(), &FInfo);
+    return MakeHolder<TPgResolvedCallState>(GetArgCount(), &FInfo, NPg::InvalidCollationOid);
 }
 
 TPgCast::TPgCast(ui32 sourceId, ui32 targetId, bool hasTypeMod)
@@ -496,7 +496,7 @@ template class TPgResolvedCall<false>;
 TPgResolvedCallWithCastState::TPgResolvedCallWithCastState(
     const TPgResolvedCall<false>& caller,
     const TVector<TPgCast>& casters)
-    : CallState(caller.GetArgCount(), &caller.GetFInfo())
+    : CallState(caller.GetArgCount(), &caller.GetFInfo(), NPg::InvalidCollationOid)
 {
     CastStates.reserve(casters.size());
     for (const auto& caster : casters) {
diff --git a/yql/essentials/parser/pg_wrapper/comp_factory_utils.h b/yql/essentials/parser/pg_wrapper/comp_factory_utils.h
index f31ebedfa9f..804ea63ab2a 100644
--- a/yql/essentials/parser/pg_wrapper/comp_factory_utils.h
+++ b/yql/essentials/parser/pg_wrapper/comp_factory_utils.h
@@ -103,7 +103,7 @@ protected:
 
 class TFunctionCallInfo {
 public:
-    TFunctionCallInfo(ui32 numArgs, const FmgrInfo* finfo);
+    TFunctionCallInfo(ui32 numArgs, const FmgrInfo* finfo, ui32 collationOid);
     ~TFunctionCallInfo();
 
     TFunctionCallInfo(const TFunctionCallInfo&) = delete;
@@ -119,7 +119,7 @@ private:
 };
 
 struct TPgResolvedCallState {
-    TPgResolvedCallState(ui32 numArgs, const FmgrInfo* finfo);
+    TPgResolvedCallState(ui32 numArgs, const FmgrInfo* finfo, ui32 collationOid);
 
     TFunctionCallInfo CallInfo;
     NKikimr::NMiniKQL::TUnboxedValueVector Args;
@@ -205,8 +205,8 @@ extern template class TPgResolvedCall<false>;
 
 struct TPgCastState {
     TPgCastState(const FmgrInfo* finfo1, const FmgrInfo* finfo2)
-        : CallInfo1(3, finfo1)
-        , CallInfo2(1, finfo2)
+        : CallInfo1(3, finfo1, NPg::InvalidCollationOid)
+        , CallInfo2(1, finfo2, NPg::InvalidCollationOid)
     {
     }
 
diff --git a/yql/essentials/parser/pg_wrapper/pg_ops.cpp b/yql/essentials/parser/pg_wrapper/pg_ops.cpp
index af7205eeb32..b9133398c22 100644
--- a/yql/essentials/parser/pg_wrapper/pg_ops.cpp
+++ b/yql/essentials/parser/pg_wrapper/pg_ops.cpp
@@ -52,8 +52,8 @@ public:
         : ZeroInterval_(zeroInterval)
         , EqCall_(eqCall)
         , GtCall_(gtCall)
-        , EqState_(MakeHolder<TPgResolvedCallState>(eqCall.GetArgCount(), &eqCall.GetFInfo()))
-        , GtState_(MakeHolder<TPgResolvedCallState>(gtCall.GetArgCount(), &gtCall.GetFInfo()))
+        , EqState_(MakeHolder<TPgResolvedCallState>(eqCall.GetArgCount(), &eqCall.GetFInfo(), NPg::InvalidCollationOid))
+        , GtState_(MakeHolder<TPgResolvedCallState>(gtCall.GetArgCount(), &gtCall.GetFInfo(), NPg::InvalidCollationOid))
     {
     }
 
diff --git a/yql/essentials/parser/pg_wrapper/syscache.cpp b/yql/essentials/parser/pg_wrapper/syscache.cpp
index 6e476f45108..7e95e9e3dfe 100644
--- a/yql/essentials/parser/pg_wrapper/syscache.cpp
+++ b/yql/essentials/parser/pg_wrapper/syscache.cpp
@@ -12,6 +12,7 @@ extern "C" {
 #include "catalog/pg_namespace.h"
 #include "catalog/pg_type.h"
 #include "catalog/pg_type_d.h"
+#include "catalog/pg_collation.h"
 #include "catalog/pg_authid.h"
 #include "access/htup_details.h"
 #include "utils/fmgroids.h"
@@ -129,7 +130,7 @@ bool ByNameProcEquals3(const THeapTupleKey& key1, const THeapTupleKey& key2) {
 }
 
 struct TSysCacheItem {
-    TSysCacheItem(THeapTupleHasher hasher, THeapTupleEquals equals, TupleDesc desc, ui32 numKeys = 1, 
+    TSysCacheItem(THeapTupleHasher hasher, THeapTupleEquals equals, TupleDesc desc, ui32 numKeys = 1,
         THeapTupleHasher hasherRange1 = {}, THeapTupleEquals equalsRange1 = {})
         : NumKeys(numKeys)
         , LookupMap(0, hasher, equals)
@@ -199,7 +200,7 @@ struct TSysCache {
 
     static TSysCache& MutableInstance() {
         return *Singleton<TSysCache>();
-    }    
+    }
 
     TSysCache()
     {
@@ -219,6 +220,7 @@ struct TSysCache {
 
             InitializeProcs();
             InitializeTypes();
+            InitializeCollations();
             InitializeDatabase();
             InitializeAuthId();
             InitializeNameAndOidNamespaces();
@@ -477,7 +479,7 @@ struct TSysCache {
             Y_ENSURE(row->typalign == desc.TypeAlign);
             Y_ENSURE(row->typstorage == storage);
 
-            auto key1 = THeapTupleKey(oid, 0, 0, 0);            
+            auto key1 = THeapTupleKey(oid, 0, 0, 0);
             lookupMap1.emplace(key1, h);
             auto key2 = THeapTupleKey((Datum)desc.Name.c_str(), PG_CATALOG_NAMESPACE, 0, 0);
             lookupMap2.emplace(key2, h);
@@ -485,6 +487,59 @@ struct TSysCache {
 
     }
 
+    void InitializeCollations() {
+        TupleDesc tupleDesc = CreateTemplateTupleDesc(Natts_pg_collation);
+        FillAttr(tupleDesc, Anum_pg_collation_oid, OIDOID);
+        FillAttr(tupleDesc, Anum_pg_collation_collname, NAMEOID);
+        FillAttr(tupleDesc, Anum_pg_collation_collnamespace, OIDOID);
+        FillAttr(tupleDesc, Anum_pg_collation_collowner, OIDOID);
+        FillAttr(tupleDesc, Anum_pg_collation_collprovider, CHAROID);
+        FillAttr(tupleDesc, Anum_pg_collation_collisdeterministic, BOOLOID);
+        FillAttr(tupleDesc, Anum_pg_collation_collencoding, INT4OID);
+        FillAttr(tupleDesc, Anum_pg_collation_collcollate, TEXTOID);
+        FillAttr(tupleDesc, Anum_pg_collation_collctype, TEXTOID);
+        FillAttr(tupleDesc, Anum_pg_collation_colliculocale, TEXTOID);
+        FillAttr(tupleDesc, Anum_pg_collation_collicurules, TEXTOID);
+        FillAttr(tupleDesc, Anum_pg_collation_collversion, TEXTOID);
+
+        auto& cacheItem = Items[COLLOID] = std::make_unique<TSysCacheItem>(OidHasher1, OidEquals1, tupleDesc);
+        auto& lookupMap = cacheItem->LookupMap;
+
+        NPg::EnumCollation([&](ui32 oid, const NPg::TCollationDesc& desc) {
+            Datum values[Natts_pg_collation];
+            bool nulls[Natts_pg_collation];
+            Zero(values);
+            std::fill_n(nulls, Natts_pg_collation, true);
+            std::fill_n(nulls, Anum_pg_collation_collencoding, false); // fixed part of Form_pg_collation
+            FillDatum(Natts_pg_collation, values, nulls, Anum_pg_collation_oid, oid);
+            auto name = MakeFixedString(desc.Name, NAMEDATALEN);
+            FillDatum(Natts_pg_collation, values, nulls, Anum_pg_collation_collname, (Datum)name);
+            FillDatum(Natts_pg_collation, values, nulls, Anum_pg_collation_collnamespace, PG_CATALOG_NAMESPACE);
+            FillDatum(Natts_pg_collation, values, nulls, Anum_pg_collation_collowner, 1);
+            FillDatum(Natts_pg_collation, values, nulls, Anum_pg_collation_collprovider, (char)desc.Provider);
+            FillDatum(Natts_pg_collation, values, nulls, Anum_pg_collation_collisdeterministic, true);
+            FillDatum(Natts_pg_collation, values, nulls, Anum_pg_collation_collencoding, desc.Encoding);
+            if (!desc.Collate.empty()) {
+                FillDatum(Natts_pg_collation, values, nulls, Anum_pg_collation_collcollate, (Datum)MakeVar(desc.Collate));
+            }
+            if (!desc.Ctype.empty()) {
+                FillDatum(Natts_pg_collation, values, nulls, Anum_pg_collation_collctype, (Datum)MakeVar(desc.Ctype));
+            }
+            if (!desc.IcuLocale.empty()) {
+                FillDatum(Natts_pg_collation, values, nulls, Anum_pg_collation_colliculocale, (Datum)MakeVar(desc.IcuLocale));
+            }
+
+            HeapTuple h = heap_form_tuple(tupleDesc, values, nulls);
+            auto row = (Form_pg_collation)GETSTRUCT(h);
+            Y_ENSURE(row->oid == oid);
+            Y_ENSURE(NameStr(row->collname) == desc.Name);
+            Y_ENSURE(row->collprovider == (char)desc.Provider);
+
+            auto key = THeapTupleKey(oid, 0, 0, 0);
+            lookupMap.emplace(key, h);
+        });
+    }
+
     static HeapTuple MakePgDatabaseHeapTuple(ui32 oid, const char* name) {
         TupleDesc tupleDesc = CreateTemplateTupleDesc(Natts_pg_database);
         FillAttr(tupleDesc, Anum_pg_database_oid, OIDOID);
diff --git a/yql/essentials/providers/common/mkql/yql_provider_mkql.cpp b/yql/essentials/providers/common/mkql/yql_provider_mkql.cpp
index d3f2d071b18..21b1137e6ef 100644
--- a/yql/essentials/providers/common/mkql/yql_provider_mkql.cpp
+++ b/yql/essentials/providers/common/mkql/yql_provider_mkql.cpp
@@ -2819,14 +2819,17 @@ TMkqlCommonCallableCompiler::TShared::TShared() {
         }
 
         bool rangeFunction = false;
+        ui32 collationOid = 0;
         for (const auto& child : node.Child(2)->Children()) {
             if (child->Head().Content() == "range") {
                 rangeFunction = true;
+            } else if (child->Head().Content() == "collation_oid") {
+                collationOid = FromString<ui32>(child->Tail().Content());
             }
         }
 
         auto returnType = ctx.BuildType(node, *node.GetTypeAnn());
-        return ctx.ProgramBuilder.PgResolvedCall(node.IsCallable("PgResolvedCallCtx"), name, id, args, returnType, rangeFunction);
+        return ctx.ProgramBuilder.PgResolvedCall(node.IsCallable("PgResolvedCallCtx"), name, id, args, returnType, rangeFunction, collationOid);
     });
 
     AddCallable("PgResolvedOp", [](const TExprNode& node, TMkqlBuildContext& ctx) {
@@ -2840,7 +2843,7 @@ TMkqlCommonCallableCompiler::TShared::TShared() {
         }
 
         auto returnType = ctx.BuildType(node, *node.GetTypeAnn());
-        return ctx.ProgramBuilder.PgResolvedCall(/*useContext=*/false, procName, procId, args, returnType, /*rangeFunction=*/false);
+        return ctx.ProgramBuilder.PgResolvedCall(/*useContext=*/false, procName, procId, args, returnType, /*rangeFunction=*/false, NPg::InvalidCollationOid);
     });
 
     AddCallable("BlockPgResolvedCall", [](const TExprNode& node, TMkqlBuildContext& ctx) {
@@ -2852,8 +2855,15 @@ TMkqlCommonCallableCompiler::TShared::TShared() {
             args.push_back(MkqlBuildExpr(*node.Child(i), ctx));
         }
 
+        ui32 collationOid = 0;
+        for (const auto& child : node.Child(2)->Children()) {
+            if (child->Head().Content() == "collation_oid") {
+                collationOid = FromString<ui32>(child->Tail().Content());
+            }
+        }
+
         auto returnType = ctx.BuildType(node, *node.GetTypeAnn());
-        return ctx.ProgramBuilder.BlockPgResolvedCall(name, id, args, returnType);
+        return ctx.ProgramBuilder.BlockPgResolvedCall(name, id, args, returnType, collationOid);
     });
 
     AddCallable("BlockPgResolvedOp", [](const TExprNode& node, TMkqlBuildContext& ctx) {
@@ -2867,7 +2877,7 @@ TMkqlCommonCallableCompiler::TShared::TShared() {
         }
 
         auto returnType = ctx.BuildType(node, *node.GetTypeAnn());
-        return ctx.ProgramBuilder.BlockPgResolvedCall(procName, procId, args, returnType);
+        return ctx.ProgramBuilder.BlockPgResolvedCall(procName, procId, args, returnType, NPg::InvalidCollationOid);
     });
 
     AddCallable("PgCast", [](const TExprNode& node, TMkqlBuildContext& ctx) {
diff --git a/yql/essentials/sql/pg/pg_sql.cpp b/yql/essentials/sql/pg/pg_sql.cpp
index 6990cbfefa7..9ea2a53e936 100644
--- a/yql/essentials/sql/pg/pg_sql.cpp
+++ b/yql/essentials/sql/pg/pg_sql.cpp
@@ -3725,6 +3725,33 @@ public:
         return result;
     }
 
+    bool ExtractCollationName(const CollateClause* value, TString& name) {
+        auto len = ListLength(value->collname);
+        if (len == 0) {
+            AddError("CollateClause: missing collation name");
+            return false;
+        }
+
+        auto x = ListNodeNth(value->collname, len - 1);
+        if (NodeTag(x) != T_String) {
+            NodeNotImplemented(value, x);
+            return false;
+        }
+
+        name = StrVal(x);
+        return true;
+    }
+
+    TAstNode* ParseCollateClause(const CollateClause* value, const TExprSettings& settings) {
+        AT_LOCATION(value);
+        // Collation propagation through arbitrary expressions (COALESCE, CASE, plain
+        // projections, ...) is not implemented - only ParseFuncCall picks up an explicit
+        // COLLATE that directly wraps one of its arguments (see there). Elsewhere COLLATE
+        // only affects collation-sensitive semantics (comparison, case mapping), not the
+        // expression's runtime value, so we just parse through to the wrapped expression.
+        return ParseExpr(value->arg, settings);
+    }
+
     TAstNode* ParseExpr(const Node* node, const TExprSettings& settings) {
         switch (NodeTag(node)) {
             case T_A_Const: {
@@ -3742,6 +3769,9 @@ public:
             case T_TypeCast: {
                 return ParseTypeCast(CAST_NODE(TypeCast, node), settings);
             }
+            case T_CollateClause: {
+                return ParseCollateClause(CAST_NODE(CollateClause, node), settings);
+            }
             case T_BoolExpr: {
                 return ParseBoolExpr(CAST_NODE(BoolExpr, node), settings);
             }
@@ -4267,6 +4297,32 @@ public:
             callSettings.push_back(QL(QA("range")));
         }
 
+        if (!value->agg_star) {
+            TMaybe<TString> collation;
+            for (int i = 0; i < ListLength(value->args); ++i) {
+                auto x = ListNodeNth(value->args, i);
+                if (NodeTag(x) != T_CollateClause) {
+                    continue;
+                }
+
+                TString collationName;
+                if (!ExtractCollationName(CAST_NODE(CollateClause, x), collationName)) {
+                    return nullptr;
+                }
+
+                if (collation && *collation != collationName) {
+                    AddError(TStringBuilder() << "FuncCall: conflicting explicit collations: " << *collation << " and " << collationName);
+                    return nullptr;
+                }
+
+                collation = collationName;
+            }
+
+            if (collation) {
+                callSettings.push_back(QL(QA("collation"), QAX(*collation)));
+            }
+        }
+
         args.push_back(QVL(callSettings.data(), callSettings.size()));
         if (value->agg_star) {
             if (name != "count") {
diff --git a/yql/essentials/sql/v1/builtin.cpp b/yql/essentials/sql/v1/builtin.cpp
index cb91f956f89..43eeb6af9b4 100644
--- a/yql/essentials/sql/v1/builtin.cpp
+++ b/yql/essentials/sql/v1/builtin.cpp
@@ -860,7 +860,35 @@ public:
         }
 
         Args_[0] = BuildQuotedAtom(Args_[0]->GetPos(), Args_[0]->GetLiteralValue());
-        Args_.insert(Args_.begin() + 1, RangeFunction ? Q(Y(Q(Y(Q("range"))))) : Q(Y()));
+
+        TNodePtr settingsList = Y();
+        if (RangeFunction) {
+            settingsList = L(settingsList, Q(Y(Q("range"))));
+        }
+
+        // Optional named argument: PgCall("upper", x, "de-DE-x-icu" as Collation)
+        for (size_t i = 1; i < Args_.size();) {
+            const auto& label = Args_[i]->GetLabel();
+            if (label.empty()) {
+                ++i;
+                continue;
+            }
+
+            if (label != "Collation") {
+                ctx.Error(Args_[i]->GetPos()) << "PgCall: unsupported named argument: " << label << "; expected: Collation";
+                return false;
+            }
+
+            auto arg = Args_[i];
+            if (!arg->Init(ctx, src)) {
+                return false;
+            }
+
+            settingsList = L(settingsList, Q(Y(Q("collation"), MakeAtomFromExpression(Pos_, ctx, arg).Build())));
+            Args_.erase(Args_.begin() + i);
+        }
+
+        Args_.insert(Args_.begin() + 1, Q(settingsList));
         return TCallNode::DoInit(ctx, src);
     }
 
@@ -4218,6 +4246,28 @@ TNodeResult BuildBuiltinFunc(
             return TNonNull(TNodePtr(new TInvalidBuiltin(pos, "DISTINCT can only be used in aggregation functions")));
         }
 
+        if ((normalizedName == "pgcall" || normalizedName == "pgrangecall") && mustUseNamed && *mustUseNamed) {
+            // PgCall/PgRangeCall support one named argument (collation => ...); TYqlPgCall::DoInit
+            // finds it by label, so just flatten the (positional tuple, named struct) pair that
+            // named-arg calls get reshaped into back into a single labeled arg list.
+            *mustUseNamed = false;
+            YQL_ENSURE(args.size() == 2);
+            auto positional = args[0]->GetTupleNode();
+            YQL_ENSURE(positional);
+            auto named = args[1]->GetStructNode();
+            YQL_ENSURE(named);
+
+            TVector<TNodePtr> flatArgs(positional->Elements());
+            for (const auto& arg : named->GetExprs()) {
+                flatArgs.push_back(arg);
+            }
+
+            const bool isRange = (normalizedName == "pgrangecall");
+            return TNonNull(isRange
+                                ? TNodePtr(new TYqlPgCall<true>(pos, flatArgs))
+                                : TNodePtr(new TYqlPgCall<false>(pos, flatArgs)));
+        }
+
         auto builtinCallback = builtinFuncs.find(normalizedName);
         if (builtinCallback != builtinFuncs.end()) {
             const auto& funcInfo = builtinCallback->second;
diff --git a/yql/essentials/tests/s-expressions/minirun/part4/canondata/result.json b/yql/essentials/tests/s-expressions/minirun/part4/canondata/result.json
index df0cc6a07e6..60a9d0991af 100644
--- a/yql/essentials/tests/s-expressions/minirun/part4/canondata/result.json
+++ b/yql/essentials/tests/s-expressions/minirun/part4/canondata/result.json
@@ -251,6 +251,20 @@
             "uri": "https://{canondata_backend}/1937424/d5a759bb3d448219023419bd81b51a83c51e7fb9/resource.tar.gz#test.test_InMem-Guess--Results_/results.txt"
         }
     ],
+    "test.test[InMem-LPartitionsByKeys-default.txt-Debug]": [
+        {
+            "checksum": "c5970844f3cd290c9cd0f6da7c09a92e",
+            "size": 537,
+            "uri": "https://{canondata_backend}/1903885/04250d1ff8dfb75396270ac9221941404e83162d/resource.tar.gz#test.test_InMem-LPartitionsByKeys-default.txt-Debug_/opt.yql"
+        }
+    ],
+    "test.test[InMem-LPartitionsByKeys-default.txt-Results]": [
+        {
+            "checksum": "3159d6b27773bf2c0b434a77a64b62b2",
+            "size": 337,
+            "uri": "https://{canondata_backend}/1903885/04250d1ff8dfb75396270ac9221941404e83162d/resource.tar.gz#test.test_InMem-LPartitionsByKeys-default.txt-Results_/results.txt"
+        }
+    ],
     "test.test[InMem-ListFromRangeForDates-default.txt-Debug]": [
         {
             "checksum": "9eb52e1fd2ea6bda896e831fdf864f27",
diff --git a/yql/essentials/tests/s-expressions/minirun/part9/canondata/result.json b/yql/essentials/tests/s-expressions/minirun/part9/canondata/result.json
index d9ea295302a..2a3a50eef4e 100644
--- a/yql/essentials/tests/s-expressions/minirun/part9/canondata/result.json
+++ b/yql/essentials/tests/s-expressions/minirun/part9/canondata/result.json
@@ -209,6 +209,20 @@
             "uri": "https://{canondata_backend}/1936842/97e0ab044a6a521639a649b6b781407443c8c0f8/resource.tar.gz#test.test_InMem-Iterator-default.txt-Results_/results.txt"
         }
     ],
+    "test.test[InMem-LPartitionsByKeysSorted-default.txt-Debug]": [
+        {
+            "checksum": "344f7eae976694446bf07e0a90cd6f07",
+            "size": 566,
+            "uri": "https://{canondata_backend}/1814674/2df5cbfd5d5a594d9f476819b99ebb23ca848426/resource.tar.gz#test.test_InMem-LPartitionsByKeysSorted-default.txt-Debug_/opt.yql"
+        }
+    ],
+    "test.test[InMem-LPartitionsByKeysSorted-default.txt-Results]": [
+        {
+            "checksum": "20b62fca5b0e72f0ca2df54d7d61a5e2",
+            "size": 337,
+            "uri": "https://{canondata_backend}/1814674/2df5cbfd5d5a594d9f476819b99ebb23ca848426/resource.tar.gz#test.test_InMem-LPartitionsByKeysSorted-default.txt-Results_/results.txt"
+        }
+    ],
     "test.test[InMem-ReplaceMember-default.txt-Debug]": [
         {
             "checksum": "356532c5c41738b56f422acc79110cbc",
diff --git a/yql/essentials/tests/s-expressions/suites/InMem/LPartitionsByKeys.yqls b/yql/essentials/tests/s-expressions/suites/InMem/LPartitionsByKeys.yqls
new file mode 100644
index 00000000000..15e48a09766
--- /dev/null
+++ b/yql/essentials/tests/s-expressions/suites/InMem/LPartitionsByKeys.yqls
@@ -0,0 +1,22 @@
+(
+#comment
+(let config (DataSource 'config))
+
+(let res_sink (DataSink 'result))
+(let list (AsList
+'((Uint32 '1) (String 'a))
+'((Uint32 '2) (String 'b))
+'((Uint32 '1) (String 'c))))
+
+(let keyExtractor (lambda '(x) (Nth x '0)))
+(let handler (lambda '(x) (Condense1 x
+    (lambda '(row) '((Nth row '0) (Concat (String '"values:") (ToString (Nth row '1)))))
+    (lambda '(row state) (AggrNotEquals (Nth row '0) (Nth state '0)))
+    (lambda '(row state) '((Nth state '0) (Concat (Concat (Nth state '1) (String '" ")) (Nth row '1))))
+)))
+(let data (LPartitionsByKeys list keyExtractor (Void) (Void) handler))
+
+(let world (Write! world res_sink (Key) data '()))
+(let world (Commit! world res_sink))
+(return world)
+)
diff --git a/yql/essentials/tests/s-expressions/suites/InMem/LPartitionsByKeysSorted.yqls b/yql/essentials/tests/s-expressions/suites/InMem/LPartitionsByKeysSorted.yqls
new file mode 100644
index 00000000000..3d20a56d06e
--- /dev/null
+++ b/yql/essentials/tests/s-expressions/suites/InMem/LPartitionsByKeysSorted.yqls
@@ -0,0 +1,23 @@
+(
+#comment
+(let config (DataSource 'config))
+
+(let res_sink (DataSink 'result))
+(let list (AsList
+'((Uint32 '1) (String 'a))
+'((Uint32 '2) (String 'b))
+'((Uint32 '1) (String 'c))))
+
+(let keyExtractor (lambda '(x) (Nth x '0)))
+(let subkeyExtractor (lambda '(x) (Nth x '1)))
+(let handler (lambda '(x) (Condense1 x
+    (lambda '(row) '((Nth row '0) (Concat (String '"values:") (ToString (Nth row '1)))))
+    (lambda '(row state) (AggrNotEquals (Nth row '0) (Nth state '0)))
+    (lambda '(row state) '((Nth state '0) (Concat (Concat (Nth state '1) (String '" ")) (Nth row '1))))
+)))
+(let data (LPartitionsByKeys list keyExtractor (Bool 'false) subkeyExtractor handler))
+
+(let world (Write! world res_sink (Key) data '()))
+(let world (Commit! world res_sink))
+(return world)
+)
diff --git a/yql/essentials/tests/sql/minirun/part0/canondata/result.json b/yql/essentials/tests/sql/minirun/part0/canondata/result.json
index aaf0e9ac659..90221a7ca8b 100644
--- a/yql/essentials/tests/sql/minirun/part0/canondata/result.json
+++ b/yql/essentials/tests/sql/minirun/part0/canondata/result.json
@@ -951,6 +951,20 @@
             "uri": "https://{canondata_backend}/1937424/d02bb271c9ab67557c669f52bc80a0a698a8a91e/resource.tar.gz#test.test_pg-YQL_20895_having_depth_3-default.txt-Results_/results.txt"
         }
     ],
+    "test.test[pg-collate_icu-default.txt-Debug]": [
+        {
+            "checksum": "1652b1b4cff4644c499e6dc69fee811c",
+            "size": 765,
+            "uri": "https://{canondata_backend}/1871102/3abca1c03e1dffe75d1d9477b6aa625e8d988fcc/resource.tar.gz#test.test_pg-collate_icu-default.txt-Debug_/opt.yql"
+        }
+    ],
+    "test.test[pg-collate_icu-default.txt-Results]": [
+        {
+            "checksum": "b0b6a05f71c0ea34ff54854f875e6e0f",
+            "size": 1731,
+            "uri": "https://{canondata_backend}/1871102/3abca1c03e1dffe75d1d9477b6aa625e8d988fcc/resource.tar.gz#test.test_pg-collate_icu-default.txt-Results_/results.txt"
+        }
+    ],
     "test.test[pg-distinct_from_pg_null-default.txt-Debug]": [
         {
             "checksum": "28eb3cf7598e0504999612fc78525b89",
diff --git a/yql/essentials/tests/sql/minirun/part10/canondata/result.json b/yql/essentials/tests/sql/minirun/part10/canondata/result.json
index eebfb9f633a..c8688325f56 100644
--- a/yql/essentials/tests/sql/minirun/part10/canondata/result.json
+++ b/yql/essentials/tests/sql/minirun/part10/canondata/result.json
@@ -349,6 +349,27 @@
             "uri": "https://{canondata_backend}/1777230/52d24600ceada6f625f4161edfba1861d2eed32d/resource.tar.gz#test.test_blocks-pg_call-default.txt-Results_/results.txt"
         }
     ],
+    "test.test[blocks-pg_call_collation-default.txt-Debug]": [
+        {
+            "checksum": "06af59fe488e80891c72af615fab34d8",
+            "size": 567,
+            "uri": "https://{canondata_backend}/1936842/42d71fee557fda1f6e31e9529eb8834c94fcba49/resource.tar.gz#test.test_blocks-pg_call_collation-default.txt-Debug_/opt.yql"
+        }
+    ],
+    "test.test[blocks-pg_call_collation-default.txt-Peephole]": [
+        {
+            "checksum": "451da6daf3dc9800234a3a74b45a874b",
+            "size": 732,
+            "uri": "https://{canondata_backend}/1936842/42d71fee557fda1f6e31e9529eb8834c94fcba49/resource.tar.gz#test.test_blocks-pg_call_collation-default.txt-Peephole_/opt.yql"
+        }
+    ],
+    "test.test[blocks-pg_call_collation-default.txt-Results]": [
+        {
+            "checksum": "15b1272df7ce88bf65e3f49c899e5b02",
+            "size": 1182,
+            "uri": "https://{canondata_backend}/1936842/42d71fee557fda1f6e31e9529eb8834c94fcba49/resource.tar.gz#test.test_blocks-pg_call_collation-default.txt-Results_/results.txt"
+        }
+    ],
     "test.test[blocks-take_skip-default.txt-Debug]": [
         {
             "checksum": "14f19770f1c340e0707f94dd4c9351f4",
diff --git a/yql/essentials/tests/sql/minirun/part2/canondata/result.json b/yql/essentials/tests/sql/minirun/part2/canondata/result.json
index 859cdcf18ee..46167e94552 100644
--- a/yql/essentials/tests/sql/minirun/part2/canondata/result.json
+++ b/yql/essentials/tests/sql/minirun/part2/canondata/result.json
@@ -966,6 +966,20 @@
             "uri": "https://{canondata_backend}/1773845/5e187b5c8712eed0b26575ad1c84f3158af43d1d/resource.tar.gz#test.test_pg-with_rec_distinct-default.txt-Results_/results.txt"
         }
     ],
+    "test.test[pg_catalog-pg_collation-default.txt-Debug]": [
+        {
+            "checksum": "8a748166f29bb30eab0aadaa56beb680",
+            "size": 1174,
+            "uri": "https://{canondata_backend}/212715/18867d69579bd1c3245bfeba1a9a3d827bfd47f3/resource.tar.gz#test.test_pg_catalog-pg_collation-default.txt-Debug_/opt.yql"
+        }
+    ],
+    "test.test[pg_catalog-pg_collation-default.txt-Results]": [
+        {
+            "checksum": "520bb16015bf0ec808f3934ca9a32551",
+            "size": 733,
+            "uri": "https://{canondata_backend}/212715/18867d69579bd1c3245bfeba1a9a3d827bfd47f3/resource.tar.gz#test.test_pg_catalog-pg_collation-default.txt-Results_/results.txt"
+        }
+    ],
     "test.test[pg_catalog-pg_namespace_pg_syntax-default.txt-Debug]": [
         {
             "checksum": "227d6e0c6d613058c88f34d5bb633d20",
diff --git a/yql/essentials/tests/sql/minirun/part3/canondata/result.json b/yql/essentials/tests/sql/minirun/part3/canondata/result.json
index 65982115910..f987dc88b49 100644
--- a/yql/essentials/tests/sql/minirun/part3/canondata/result.json
+++ b/yql/essentials/tests/sql/minirun/part3/canondata/result.json
@@ -744,6 +744,20 @@
             "uri": "https://{canondata_backend}/1781765/e6df7efbe28b8ae403e3d9815e1579ecc8bb5445/resource.tar.gz#test.test_pg-aggregate_scalar_minus_zero-default.txt-Results_/results.txt"
         }
     ],
+    "test.test[pg-collate_std-default.txt-Debug]": [
+        {
+            "checksum": "29b4db3f942db540ae3c350b5fffa10b",
+            "size": 1426,
+            "uri": "https://{canondata_backend}/1942173/f178108c603ab2223424f5ca3701e7ac0acc65cb/resource.tar.gz#test.test_pg-collate_std-default.txt-Debug_/opt.yql"
+        }
+    ],
+    "test.test[pg-collate_std-default.txt-Results]": [
+        {
+            "checksum": "6756fa684ac9c665cdc9434bfb356e17",
+            "size": 3722,
+            "uri": "https://{canondata_backend}/1942173/f178108c603ab2223424f5ca3701e7ac0acc65cb/resource.tar.gz#test.test_pg-collate_std-default.txt-Results_/results.txt"
+        }
+    ],
     "test.test[pg-compare-default.txt-Debug]": [
         {
             "checksum": "d25a02298d33a67403f42601ea688cbe",
diff --git a/yql/essentials/tests/sql/sql2yql/canondata/result.json b/yql/essentials/tests/sql/sql2yql/canondata/result.json
index 657f918cfad..b52bb5fe2f7 100644
--- a/yql/essentials/tests/sql/sql2yql/canondata/result.json
+++ b/yql/essentials/tests/sql/sql2yql/canondata/result.json
@@ -2526,6 +2526,13 @@
             "uri": "https://{canondata_backend}/1942100/698d95eec1cbd4e4ada1a8da105c203a7a12bb85/resource.tar.gz#test_sql2yql.test_blocks-pg_call_/sql.yql"
         }
     ],
+    "test_sql2yql.test[blocks-pg_call_collation]": [
+        {
+            "checksum": "fc5bb37bca3be522317e2108bc7a25d7",
+            "size": 1384,
+            "uri": "https://{canondata_backend}/1946324/4da69cf65420cbbd1b36d493c4602a8dfff3583d/resource.tar.gz#test_sql2yql.test_blocks-pg_call_collation_/sql.yql"
+        }
+    ],
     "test_sql2yql.test[blocks-pg_op]": [
         {
             "checksum": "6fde398b5c3fed0e3fa982b753fe6018",
@@ -6929,6 +6936,20 @@
             "uri": "https://{canondata_backend}/1942100/698d95eec1cbd4e4ada1a8da105c203a7a12bb85/resource.tar.gz#test_sql2yql.test_pg-coalesce_/sql.yql"
         }
     ],
+    "test_sql2yql.test[pg-collate_icu]": [
+        {
+            "checksum": "229206950b633a4de2d73820c449ace8",
+            "size": 851,
+            "uri": "https://{canondata_backend}/1809005/58875b1649369677cd109dd8100bb7a1c63ac607/resource.tar.gz#test_sql2yql.test_pg-collate_icu_/sql.yql"
+        }
+    ],
+    "test_sql2yql.test[pg-collate_std]": [
+        {
+            "checksum": "9f81b5324fbfe2e1fc479ef1d64a87d3",
+            "size": 1647,
+            "uri": "https://{canondata_backend}/1809005/58875b1649369677cd109dd8100bb7a1c63ac607/resource.tar.gz#test_sql2yql.test_pg-collate_std_/sql.yql"
+        }
+    ],
     "test_sql2yql.test[pg-compare]": [
         {
             "checksum": "a25ef2b8abd25e4b952c428bcd821b03",
@@ -8819,6 +8840,13 @@
             "uri": "https://{canondata_backend}/1942100/698d95eec1cbd4e4ada1a8da105c203a7a12bb85/resource.tar.gz#test_sql2yql.test_pg_catalog-pg_class_/sql.yql"
         }
     ],
+    "test_sql2yql.test[pg_catalog-pg_collation]": [
+        {
+            "checksum": "57863f2853565b02219bc45355998aad",
+            "size": 659,
+            "uri": "https://{canondata_backend}/1781765/b51b8ce704a88a316462b50b2ccb16b8e6aff2d3/resource.tar.gz#test_sql2yql.test_pg_catalog-pg_collation_/sql.yql"
+        }
+    ],
     "test_sql2yql.test[pg_catalog-pg_database]": [
         {
             "checksum": "277583c5b369c99209d290134ee3c60f",
@@ -14425,6 +14453,11 @@
             "uri": "file://test_sql_format.test_blocks-pg_call_/formatted.sql"
         }
     ],
+    "test_sql_format.test[blocks-pg_call_collation]": [
+        {
+            "uri": "file://test_sql_format.test_blocks-pg_call_collation_/formatted.sql"
+        }
+    ],
     "test_sql_format.test[blocks-pg_op]": [
         {
             "uri": "file://test_sql_format.test_blocks-pg_op_/formatted.sql"
@@ -20407,6 +20440,13 @@
             "uri": "https://{canondata_backend}/1942100/698d95eec1cbd4e4ada1a8da105c203a7a12bb85/resource.tar.gz#test_sql_negative.test_match_recognize-measures_aggr_factory-_/err_file.out"
         }
     ],
+    "test_sql_negative.test[pg-fail_collate_mixed-]": [
+        {
+            "checksum": "27098fda5bb566087d95068537a89604",
+            "size": 146,
+            "uri": "https://{canondata_backend}/1925821/a0711c4178a5e0568199e19991c318a3fb84b630/resource.tar.gz#test_sql_negative.test_pg-fail_collate_mixed-_/err_file.out"
+        }
+    ],
     "test_sql_negative.test[pragma-classic_division_sqlfail-]": [
         {
             "checksum": "f1b771232b48beee3305efe6ac52b431",
diff --git a/yql/essentials/tests/sql/sql2yql/canondata/test_sql_format.test_blocks-pg_call_collation_/formatted.sql b/yql/essentials/tests/sql/sql2yql/canondata/test_sql_format.test_blocks-pg_call_collation_/formatted.sql
new file mode 100644
index 00000000000..e5b66e0f373
--- /dev/null
+++ b/yql/essentials/tests/sql/sql2yql/canondata/test_sql_format.test_blocks-pg_call_collation_/formatted.sql
@@ -0,0 +1,11 @@
+$data = [
+    <|x: "straße"p|>,
+    <|x: "foo"p|>,
+];
+
+SELECT
+    PgCall('upper', x, 'de-DE-x-icu' AS Collation),
+    PgCall('upper', x)
+FROM
+    as_table($data)
+;
diff --git a/yql/essentials/tests/sql/suites/blocks/pg_call_collation.yql b/yql/essentials/tests/sql/suites/blocks/pg_call_collation.yql
new file mode 100644
index 00000000000..028dcb31263
--- /dev/null
+++ b/yql/essentials/tests/sql/suites/blocks/pg_call_collation.yql
@@ -0,0 +1,6 @@
+$data = [
+    <|x:"straße"p|>,
+    <|x:"foo"p|>,
+];
+
+select PgCall("upper", x, "de-DE-x-icu" as Collation), PgCall("upper", x) from as_table($data);
diff --git a/yql/essentials/tests/sql/suites/pg/collate_icu.sql b/yql/essentials/tests/sql/suites/pg/collate_icu.sql
new file mode 100644
index 00000000000..5939a2a52c3
--- /dev/null
+++ b/yql/essentials/tests/sql/suites/pg/collate_icu.sql
@@ -0,0 +1,2 @@
+--!syntax_pg
+select upper('straße' COLLATE "de-DE-x-icu"), upper('straße'), upper('i' COLLATE "tr-TR-x-icu"), upper('i');
diff --git a/yql/essentials/tests/sql/suites/pg/collate_std.sql b/yql/essentials/tests/sql/suites/pg/collate_std.sql
new file mode 100644
index 00000000000..aaa80ce8759
--- /dev/null
+++ b/yql/essentials/tests/sql/suites/pg/collate_std.sql
@@ -0,0 +1,12 @@
+--!syntax_pg
+select
+    upper('straße' COLLATE "default"),
+    upper('straße' COLLATE "C"),
+    upper('straße' COLLATE "POSIX"),
+    upper('straße' COLLATE "ucs_basic"),
+    upper('straße' COLLATE "unicode"),
+    upper('i' COLLATE "default"),
+    upper('i' COLLATE "C"),
+    upper('i' COLLATE "POSIX"),
+    upper('i' COLLATE "ucs_basic"),
+    upper('i' COLLATE "unicode");
diff --git a/yql/essentials/tests/sql/suites/pg/fail_collate_mixed.cfg b/yql/essentials/tests/sql/suites/pg/fail_collate_mixed.cfg
new file mode 100644
index 00000000000..b106572754f
--- /dev/null
+++ b/yql/essentials/tests/sql/suites/pg/fail_collate_mixed.cfg
@@ -0,0 +1 @@
+xsqlfail
diff --git a/yql/essentials/tests/sql/suites/pg/fail_collate_mixed.sql b/yql/essentials/tests/sql/suites/pg/fail_collate_mixed.sql
new file mode 100644
index 00000000000..90a4cc1b1b5
--- /dev/null
+++ b/yql/essentials/tests/sql/suites/pg/fail_collate_mixed.sql
@@ -0,0 +1,4 @@
+--!syntax_pg
+/* custom error:FuncCall: conflicting explicit collations: default and C*/
+select
+    substr('foo' COLLATE "default", 1 COLLATE "C")
diff --git a/yql/essentials/tests/sql/suites/pg_catalog/pg_collation.sql b/yql/essentials/tests/sql/suites/pg_catalog/pg_collation.sql
new file mode 100644
index 00000000000..066a6da9f00
--- /dev/null
+++ b/yql/essentials/tests/sql/suites/pg_catalog/pg_collation.sql
@@ -0,0 +1,2 @@
+--!syntax_pg
+select count(*) from pg_catalog.pg_collation;
diff --git a/yt/yql/providers/yt/fmr/coordinator/impl/ut/ya.make b/yt/yql/providers/yt/fmr/coordinator/impl/ut/ya.make
index 8ca30f57288..6deb56f58d7 100644
--- a/yt/yql/providers/yt/fmr/coordinator/impl/ut/ya.make
+++ b/yt/yql/providers/yt/fmr/coordinator/impl/ut/ya.make
@@ -23,7 +23,6 @@ PEERDIR(
     yt/yql/providers/yt/fmr/test_tools/mock_time_provider
     yt/yql/providers/yt/fmr/test_tools/sorted_partitioner
     yt/yql/providers/yt/fmr/test_tools/table_data_service
-    yt/yql/providers/yt/fmr/utils/yson_block_iterator/impl
     yt/yql/providers/yt/gateway/fmr
     yt/yql/providers/yt/gateway/file
     yt/yql/providers/yt/codec/codegen/llvm16
diff --git a/yt/yql/providers/yt/fmr/coordinator/operation_manager/impl/map_reduce/yql_yt_map_reduce_stage_operation_manager.cpp b/yt/yql/providers/yt/fmr/coordinator/operation_manager/impl/map_reduce/yql_yt_map_reduce_stage_operation_manager.cpp
index b919e13dea8..bb0c896898a 100644
--- a/yt/yql/providers/yt/fmr/coordinator/operation_manager/impl/map_reduce/yql_yt_map_reduce_stage_operation_manager.cpp
+++ b/yt/yql/providers/yt/fmr/coordinator/operation_manager/impl/map_reduce/yql_yt_map_reduce_stage_operation_manager.cpp
@@ -255,6 +255,9 @@ private:
             reduceTaskParams.Input = taskInput;
             reduceTaskParams.SerializedReduceJobState = operationParams.SerializedReduceJobState;
             reduceTaskParams.ReduceOperationSpec = operationParams.ReduceOperationSpec;
+            // The map stage above always shuffles via a synthetic _yql_key_hash prefix (see
+            // GenerateIntermediateTable), unlike a plain Reduce operation's real YT-sorted input.
+            reduceTaskParams.SortByHasKeyHashPrefix = true;
 
             std::vector<TFmrTableOutputRef> outputRefs;
             std::transform(
diff --git a/yt/yql/providers/yt/fmr/coordinator/partitioner/yql_yt_reduce_partitioner.cpp b/yt/yql/providers/yt/fmr/coordinator/partitioner/yql_yt_reduce_partitioner.cpp
index 8fd368852d8..69b9a40dc92 100644
--- a/yt/yql/providers/yt/fmr/coordinator/partitioner/yql_yt_reduce_partitioner.cpp
+++ b/yt/yql/providers/yt/fmr/coordinator/partitioner/yql_yt_reduce_partitioner.cpp
@@ -3,9 +3,19 @@
 #include "yql_yt_sorted_partitioner_base.h"
 
 #include <yt/yql/providers/yt/fmr/utils/comparator/yql_yt_binary_yson_compare_impl.h>
+#include <library/cpp/yson/node/node_io.h>
 
 namespace NYql::NFmr {
 
+namespace {
+
+// Binary YSON key rows may contain arbitrary non-UTF8 bytes; text YSON escapes them, keeping error messages valid UTF-8.
+TString FormatKeyRow(const TString& binaryYsonRow) {
+    return NYT::NodeToYsonString(NYT::NodeFromYsonString(binaryYsonRow));
+}
+
+} // namespace
+
 TReducePartitioner::TReducePartitioner(
     const std::unordered_map<TFmrTableId, std::vector<TString>>& partIdsForTables,
     const std::unordered_map<TString, std::vector<TChunkStats>>& partIdStats,
@@ -47,7 +57,7 @@ TFmrTableKeysRange TReducePartitioner::GetReadRangeFromSlices(const std::vector<
     YQL_ENSURE(taskRangeLeftBorderInclusive, " task range left border should always be true for reduce paritioner");
 
     if (taskRangeLeftBorder == taskRangeRightBorder && !taskRangeRightBorderInclusive) {
-        ythrow yexception() << "Key " << taskRangeLeftBorder.Row << " takes all slice and is too large, cannot partition";
+        ythrow yexception() << "Key " << FormatKeyRow(taskRangeLeftBorder.Row) << " takes all slice and is too large, cannot partition";
     }
 
     taskRange.SetFirstKeysBound(taskRangeLeftBorder, taskRangeLeftBorderInclusive);
@@ -93,7 +103,7 @@ void TReducePartitioner::CheckMaxKeySizePerSlices(const std::vector<TSlice>& sli
 
         if (*curLeftBorder != curRightBorder) {
             if (currentFilledSlicesWeight > maxKeySizePerPart) {
-                ythrow yexception() << "Key " << curLeftBorder->Row << " weighs at least " << currentFilledSlicesWeight << " bytes which is larget than maxKeySizePerPart - " << maxKeySizePerPart << " - cannot partition";
+                ythrow yexception() << "Key " << FormatKeyRow(curLeftBorder->Row) << " weighs at least " << currentFilledSlicesWeight << " bytes which is larget than maxKeySizePerPart - " << maxKeySizePerPart << " - cannot partition";
             }
             curLeftBorder = Nothing();
             currentFilledSlicesWeight = 0;
@@ -102,7 +112,7 @@ void TReducePartitioner::CheckMaxKeySizePerSlices(const std::vector<TSlice>& sli
         }
     }
     if (currentFilledSlicesWeight > maxKeySizePerPart) {
-        ythrow yexception() << "Key " << curLeftBorder->Row << " weighs at least " << currentFilledSlicesWeight << " bytes which is larget than maxKeySizePerPart - " << maxKeySizePerPart;
+        ythrow yexception() << "Key " << FormatKeyRow(curLeftBorder->Row) << " weighs at least " << currentFilledSlicesWeight << " bytes which is larget than maxKeySizePerPart - " << maxKeySizePerPart;
     }
     CurrentLastKeyWeight_ = currentFilledSlicesWeight;
 }
diff --git a/yt/yql/providers/yt/fmr/process/yql_yt_job_fmr.cpp b/yt/yql/providers/yt/fmr/process/yql_yt_job_fmr.cpp
index 6f4bc3e7d50..7d9c7a57b7f 100644
--- a/yt/yql/providers/yt/fmr/process/yql_yt_job_fmr.cpp
+++ b/yt/yql/providers/yt/fmr/process/yql_yt_job_fmr.cpp
@@ -113,6 +113,7 @@ void TFmrUserJob::Save(IOutputStream& s) const {
         ReduceOperationSpec_,
         IsMapReduceReducer_,
         IsMapReduceMap_,
+        SortByHasKeyHashPrefix_,
         ForceTableIndexMarking_
     );
 }
@@ -132,6 +133,7 @@ void TFmrUserJob::Load(IInputStream& s) {
         ReduceOperationSpec_,
         IsMapReduceReducer_,
         IsMapReduceMap_,
+        SortByHasKeyHashPrefix_,
         ForceTableIndexMarking_
     );
 }
@@ -283,6 +285,15 @@ void TFmrUserJob::FillQueueFromReduceInput() {
     YQL_ENSURE(ReduceOperationSpec_.Defined());
     auto reduceBy = ReduceOperationSpec_->ReduceBy;
     auto sortBy = ReduceOperationSpec_->SortBy;
+    // sortBy is [...reduceBy, ...tiebreaker] (e.g. a join's "_yql_sort"), with a leading
+    // _yql_key_hash only for MapReduce's hash-shuffled intermediate tables (SortByHasKeyHashPrefix_,
+    // set by the coordinator - see TReduceTaskParams::SortByHasKeyHashPrefix) - a plain Reduce
+    // reads its input pre-sorted by the real reduceBy columns, with no hash involved. Either
+    // way, task boundaries must only constrain on the reduce-key prefix (hash-if-present +
+    // reduceBy) - see the comment on CompareRowToBoundaryPrefix for why comparing the tiebreaker
+    // too would silently split a reduce group across tasks whenever a task cut lands between
+    // rows that share a reduce key but differ in tiebreaker.
+    const size_t numBoundaryKeyColumns = (SortByHasKeyHashPrefix_ ? 1 : 0) + reduceBy.Columns.size();
     for (const auto& inputTableRef : InputTables_.Inputs) {
         if (auto fmrInput = std::get_if<TFmrTableInputRef>(&inputTableRef)) {
             blockIterators.push_back(MakeIntrusive<TTableDataServiceBlockIterator>(
@@ -296,7 +307,9 @@ void TFmrUserJob::FillQueueFromReduceInput() {
                 fmrInput->IsFirstRowInclusive,
                 fmrInput->IsLastRowInclusive,
                 fmrInput->FirstRowKeys,
-                fmrInput->LastRowKeys
+                fmrInput->LastRowKeys,
+                /*readAheadChunks*/ ui64{4},
+                numBoundaryKeyColumns
             ));
         } else {
             ythrow TFmrNonRetryableJobException() << "YtTables unsupported inside Reduce task for now";
@@ -486,7 +499,8 @@ TStatistics TFmrUserJob::DoFmrJob(const TFmrUserJobOptions& options) {
             sortedWriter->NotifyRowEnd();
         }
         sortedWriter->Flush();
-        TStatistics result({{OutputTables_[0], sortedWriter->GetStats()}});
+        auto sortedWriterStats = sortedWriter->GetStats();
+        TStatistics result({{OutputTables_[0], sortedWriterStats}});
 
         // Direct (map-bypass) outputs at indices 1..K were already written to the real TDS via
         // their normal writers (see InitializeFmrUserJob) and flushed generically by
diff --git a/yt/yql/providers/yt/fmr/process/yql_yt_job_fmr.h b/yt/yql/providers/yt/fmr/process/yql_yt_job_fmr.h
index 54a8ff4ffde..a0bf4c70c07 100644
--- a/yt/yql/providers/yt/fmr/process/yql_yt_job_fmr.h
+++ b/yt/yql/providers/yt/fmr/process/yql_yt_job_fmr.h
@@ -116,6 +116,14 @@ public:
         IsMapReduceMap_ = value;
     }
 
+    // Whether this Reduce job's input is sorted by [_yql_key_hash, ...ReduceOperationSpec's
+    // SortBy] (a MapReduce operation's reduce stage) or by SortBy alone with no hash column at
+    // all (a plain Reduce operation reading real YT-sorted input) - see
+    // TReduceTaskParams::SortByHasKeyHashPrefix, which this is set from.
+    void SetSortByHasKeyHashPrefix(bool value) {
+        SortByHasKeyHashPrefix_ = value;
+    }
+
     // Set by the gateway (from execCtx->InputTables_, before this job's state is serialized to
     // workers) whenever the ORIGINAL OPERATION has more than one distinct input position (e.g. a
     // JOIN's mapper reading the same or different tables via multiple sections). This must be a
@@ -180,6 +188,7 @@ private:
     TMaybe<TReduceOperationSpec> ReduceOperationSpec_;
     bool IsMapReduceReducer_ = false;
     bool IsMapReduceMap_ = false;
+    bool SortByHasKeyHashPrefix_ = false;
     bool ForceTableIndexMarking_ = false;
     // End of serializable part
 
diff --git a/yt/yql/providers/yt/fmr/proto/request_options.proto b/yt/yql/providers/yt/fmr/proto/request_options.proto
index aacb3822b15..aafb3f2a32a 100644
--- a/yt/yql/providers/yt/fmr/proto/request_options.proto
+++ b/yt/yql/providers/yt/fmr/proto/request_options.proto
@@ -300,6 +300,11 @@ message TReduceTaskParams {
     repeated TFmrTableOutputRef Output = 2;
     bytes SerializedReduceJobState = 3;
     TReduceOperationSpec ReduceOperationSpec = 4;
+    // Whether Input's rows are sorted by [_yql_key_hash, ...ReduceOperationSpec.SortBy] (true for
+    // a MapReduce operation's reduce stage, which shuffles via a synthetic hash column) or by
+    // ReduceOperationSpec.SortBy alone (a plain Reduce operation, which reads real YT-sorted
+    // input with no hash column at all).
+    bool SortByHasKeyHashPrefix = 5;
 }
 
 message TSortOperationParams {
diff --git a/yt/yql/providers/yt/fmr/request_options/proto_helpers/yql_yt_request_proto_helpers.cpp b/yt/yql/providers/yt/fmr/request_options/proto_helpers/yql_yt_request_proto_helpers.cpp
index 855b572b486..c8f992255b6 100644
--- a/yt/yql/providers/yt/fmr/request_options/proto_helpers/yql_yt_request_proto_helpers.cpp
+++ b/yt/yql/providers/yt/fmr/request_options/proto_helpers/yql_yt_request_proto_helpers.cpp
@@ -717,6 +717,7 @@ NProto::TReduceTaskParams ReduceTaskParamsToProto(const TReduceTaskParams& reduc
     protoReduceTaskParams.SetSerializedReduceJobState(reduceTaskParams.SerializedReduceJobState);
     auto protoReduceOperationSpec = ReduceOperationSpecToProto(reduceTaskParams.ReduceOperationSpec);
     protoReduceTaskParams.MutableReduceOperationSpec()->Swap(&protoReduceOperationSpec);
+    protoReduceTaskParams.SetSortByHasKeyHashPrefix(reduceTaskParams.SortByHasKeyHashPrefix);
     return protoReduceTaskParams;
 }
 
@@ -730,6 +731,7 @@ TReduceTaskParams ReduceTaskParamsFromProto(const NProto::TReduceTaskParams& pro
     reduceTaskParams.Output = outputTables;
     reduceTaskParams.SerializedReduceJobState = protoReduceTaskParams.GetSerializedReduceJobState();
     reduceTaskParams.ReduceOperationSpec = ReduceOperationSpecFromProto(protoReduceTaskParams.GetReduceOperationSpec());
+    reduceTaskParams.SortByHasKeyHashPrefix = protoReduceTaskParams.GetSortByHasKeyHashPrefix();
     return reduceTaskParams;
 }
 
diff --git a/yt/yql/providers/yt/fmr/request_options/yql_yt_request_options.h b/yt/yql/providers/yt/fmr/request_options/yql_yt_request_options.h
index a32e521ba36..a2694941ae3 100644
--- a/yt/yql/providers/yt/fmr/request_options/yql_yt_request_options.h
+++ b/yt/yql/providers/yt/fmr/request_options/yql_yt_request_options.h
@@ -538,6 +538,11 @@ struct TReduceTaskParams {
     std::vector<TFmrTableOutputRef> Output;
     TString SerializedReduceJobState;
     TReduceOperationSpec ReduceOperationSpec;
+    // Whether Input's rows are sorted by [_yql_key_hash, ...ReduceOperationSpec.SortBy] (true for
+    // a MapReduce operation's reduce stage, which shuffles via a synthetic hash column) or by
+    // ReduceOperationSpec.SortBy alone (a plain Reduce operation, which reads real YT-sorted
+    // input with no hash column at all).
+    bool SortByHasKeyHashPrefix = false;
 };
 
 // Service column added by map stage to hash-route rows to the correct reducer.
diff --git a/yt/yql/providers/yt/fmr/utils/yson_block_iterator/impl/ut/ya.make b/yt/yql/providers/yt/fmr/utils/yson_block_iterator/impl/ut/ya.make
new file mode 100644
index 00000000000..61a5d2ff9f6
--- /dev/null
+++ b/yt/yql/providers/yt/fmr/utils/yson_block_iterator/impl/ut/ya.make
@@ -0,0 +1,17 @@
+UNITTEST()
+
+SRCS(
+    yql_yt_yson_tds_block_iterator_ut.cpp
+)
+
+PEERDIR(
+    yt/yql/providers/yt/fmr/utils/yson_block_iterator/impl
+    yt/yql/providers/yt/fmr/request_options
+    yt/yql/providers/yt/fmr/table_data_service/local/impl
+    yt/yql/providers/yt/fmr/test_tools/yson
+    yt/yql/providers/yt/fmr/utils
+)
+
+YQL_LAST_ABI_VERSION()
+
+END()
diff --git a/yt/yql/providers/yt/fmr/utils/yson_block_iterator/impl/ut/yql_yt_yson_tds_block_iterator_ut.cpp b/yt/yql/providers/yt/fmr/utils/yson_block_iterator/impl/ut/yql_yt_yson_tds_block_iterator_ut.cpp
new file mode 100644
index 00000000000..e2f92d30156
--- /dev/null
+++ b/yt/yql/providers/yt/fmr/utils/yson_block_iterator/impl/ut/yql_yt_yson_tds_block_iterator_ut.cpp
@@ -0,0 +1,88 @@
+#include <library/cpp/testing/unittest/registar.h>
+
+#include <yt/yql/providers/yt/fmr/utils/yson_block_iterator/impl/yql_yt_yson_tds_block_iterator.h>
+#include <yt/yql/providers/yt/fmr/test_tools/yson/yql_yt_yson_helpers.h>
+#include <yt/yql/providers/yt/fmr/table_data_service/local/impl/yql_yt_table_data_service_local.h>
+#include <yt/yql/providers/yt/fmr/utils/yql_yt_table_data_service_key.h>
+
+namespace NYql::NFmr {
+
+namespace {
+
+// Two rows sharing the same reduce key (_yql_key_hash=1, k=5) but differing only in the
+// tiebreaker column _yql_sort - e.g. a join's build-side row (sort=0) and one of its probe-side
+// rows (sort=1). Mirrors the real production row shape from yt/yql/providers/yt/fmr/job/impl/
+// yql_yt_reduce_reader.cpp's dumps.
+const TVector<TString> KeyColumns = {"_yql_key_hash", "k", "_yql_sort"};
+
+std::vector<TIndexedBlock> ReadAllBlocks(TTableDataServiceBlockIterator::TPtr iter) {
+    std::vector<TIndexedBlock> blocks;
+    TIndexedBlock block;
+    while (iter->NextBlock(block)) {
+        blocks.push_back(block);
+    }
+    return blocks;
+}
+
+ui64 CountRows(const std::vector<TIndexedBlock>& blocks) {
+    ui64 total = 0;
+    for (const auto& b : blocks) {
+        total += b.Rows.size();
+    }
+    return total;
+}
+
+} // namespace
+
+Y_UNIT_TEST_SUITE(TableDataServiceBlockIteratorBoundaryTests) {
+    Y_UNIT_TEST(TieBreakerColumnMustNotSplitReduceGroupAcrossBoundary) {
+        auto tds = MakeLocalTableDataService();
+        const TString tableId = "t";
+        const TString partId = "p0";
+        const TString group = GetTableDataServiceGroup(tableId, partId);
+        const TString chunkId = GetTableDataServiceChunkId(0, TString());
+
+        const TString chunkText =
+            "{\"_yql_key_hash\"=1u;\"k\"=5u;\"_yql_sort\"=0u};\n"
+            "{\"_yql_key_hash\"=1u;\"k\"=5u;\"_yql_sort\"=1u};\n";
+        tds->Put(group, chunkId, GetBinaryYson(chunkText)).GetValueSync();
+
+        // The task boundary itself is built from the sort=0 row's real key - exactly what
+        // happens in production when that row is the last physical row before a task cut.
+        const TString boundaryRow = GetBinaryYson(
+            "{\"_yql_key_hash\"=1u;\"k\"=5u;\"_yql_sort\"=0u}",
+            NYson::EYsonType::Node
+        );
+
+        std::vector<TTableRange> tableRanges = {TTableRange{.PartId = partId, .MinChunk = 0, .MaxChunk = 1}};
+        std::vector<ESortOrder> sortOrders(KeyColumns.size(), ESortOrder::Ascending);
+
+        // Without a cap (numBoundaryKeyColumns defaults to comparing every key column, including
+        // the tiebreaker): reproduces the bug - the sort=1 row looks like it's past the boundary
+        // and gets dropped, even though it shares the exact same reduce key.
+        {
+            auto iter = MakeIntrusive<TTableDataServiceBlockIterator>(
+                tableId, tableRanges, tds, KeyColumns, sortOrders,
+                /*neededColumns*/ TVector<TString>{}, /*serializedColumnGroupsSpec*/ TString(),
+                /*isFirstRowKeysInclusive*/ Nothing(), /*isLastRowKeysInclusive*/ true,
+                /*firstRowKeys*/ Nothing(), /*lastRowKeys*/ boundaryRow
+            );
+            UNIT_ASSERT_VALUES_EQUAL(CountRows(ReadAllBlocks(iter)), 1);
+        }
+
+        // With the fix - numBoundaryKeyColumns=2 caps comparison to [_yql_key_hash, k], excluding
+        // _yql_sort: both rows of the reduce group survive the same boundary.
+        {
+            auto iter = MakeIntrusive<TTableDataServiceBlockIterator>(
+                tableId, tableRanges, tds, KeyColumns, sortOrders,
+                /*neededColumns*/ TVector<TString>{}, /*serializedColumnGroupsSpec*/ TString(),
+                /*isFirstRowKeysInclusive*/ Nothing(), /*isLastRowKeysInclusive*/ true,
+                /*firstRowKeys*/ Nothing(), /*lastRowKeys*/ boundaryRow,
+                /*readAheadChunks*/ ui64{4}, /*numBoundaryKeyColumns*/ size_t{2}
+            );
+            UNIT_ASSERT_VALUES_EQUAL(CountRows(ReadAllBlocks(iter)), 2);
+        }
+    }
+}
+
+} // namespace NYql::NFmr
diff --git a/yt/yql/providers/yt/fmr/utils/yson_block_iterator/impl/ya.make b/yt/yql/providers/yt/fmr/utils/yson_block_iterator/impl/ya.make
index afb3020f720..7f68fea4899 100644
--- a/yt/yql/providers/yt/fmr/utils/yson_block_iterator/impl/ya.make
+++ b/yt/yql/providers/yt/fmr/utils/yson_block_iterator/impl/ya.make
@@ -21,3 +21,7 @@ PEERDIR(
 YQL_LAST_ABI_VERSION()
 
 END()
+
+RECURSE_FOR_TESTS(
+    ut
+)
diff --git a/yt/yql/providers/yt/fmr/utils/yson_block_iterator/impl/yql_yt_yson_tds_block_iterator.cpp b/yt/yql/providers/yt/fmr/utils/yson_block_iterator/impl/yql_yt_yson_tds_block_iterator.cpp
index 584614844d9..e87a9791cbb 100644
--- a/yt/yql/providers/yt/fmr/utils/yson_block_iterator/impl/yql_yt_yson_tds_block_iterator.cpp
+++ b/yt/yql/providers/yt/fmr/utils/yson_block_iterator/impl/yql_yt_yson_tds_block_iterator.cpp
@@ -21,7 +21,8 @@ TTableDataServiceBlockIterator::TTableDataServiceBlockIterator(
     TMaybe<bool> isLastRowKeysInclusive,
     TMaybe<TString> firstRowKeys,
     TMaybe<TString> lastRowKeys,
-    ui64 readAheadChunks
+    ui64 readAheadChunks,
+    TMaybe<size_t> numBoundaryKeyColumns
 )
     : TableId_(std::move(tableId))
     , TableRanges_(std::move(tableRanges))
@@ -31,6 +32,7 @@ TTableDataServiceBlockIterator::TTableDataServiceBlockIterator(
     , NeededColumns_(std::move(neededColumns))
     , SerializedColumnGroupsSpec_(std::move(serializedColumnGroupsSpec))
     , ReadAheadChunks_(readAheadChunks)
+    , NumBoundaryKeyColumns_(numBoundaryKeyColumns.GetOrElse(KeyColumns_.size()))
 {
     if (SortOrders_.empty()) {
         SortOrders_.assign(KeyColumns_.size(), ESortOrder::Ascending);
@@ -38,6 +40,7 @@ TTableDataServiceBlockIterator::TTableDataServiceBlockIterator(
     if (SortOrders_.size() != KeyColumns_.size()) {
         ythrow yexception() << "SortOrders and KeyColumns sizes are different";
     }
+    Y_ENSURE(NumBoundaryKeyColumns_ <= KeyColumns_.size(), "numBoundaryKeyColumns must not exceed keyColumns size");
 
     if (firstRowKeys) {
         FirstBoundary_ = TFmrTableKeysBoundary(*firstRowKeys, KeyColumns_, SortOrders_);
@@ -144,24 +147,29 @@ bool IsNullColumnValue(TStringBuf blob, const TColumnOffsetRange& range) {
     return SliceRange(blob, range) == TStringBuf(&EntitySymbol, 1);
 }
 
-// FirstRowKeys/LastRowKeys boundaries are built by the coordinator from a task's chunk-stats
-// key columns (e.g. [_yql_key_hash, ...ReduceBy] for MapReduce reduce tasks), which can be a
-// strict PREFIX of the fuller key column set (e.g. [_yql_key_hash, ...SortBy]) this iterator
-// parses actual rows with. TFmrTableKeysBoundary parses its own Row bytes with the SAME
-// (fuller) key columns as the row markup, so any column beyond the boundary's real prefix comes
-// out with an IsValid()==false range - not because the value is legitimately null, but because
-// the boundary blob simply never encoded it. Comparing that as "boundary < row" (the usual
-// null-handling rule) would incorrectly exclude real rows that land exactly on the boundary, so
-// this comparison stops at the boundary's own valid prefix instead of delegating to the
-// generic null-aware CompareKeyRowsAcrossYsonBlocks.
+// FirstRowKeys/LastRowKeys boundaries are built by the coordinator from a task's chunk-stats,
+// i.e. from an actual physical row's real key - for MapReduce reduce tasks over joins that key
+// is [_yql_key_hash, ...ReduceBy, ...SortBy tiebreaker] in full, tiebreaker included, because
+// that's what TReducePartitioner sorts intermediate data by (see
+// yql_yt_map_reduce_stage_operation_manager.cpp). It is NOT reliably a strict prefix that omits
+// the tiebreaker: whichever physical row happens to land on a task cut contributes its own real
+// tiebreaker value to the boundary blob. So this can't stop at "wherever the boundary blob runs
+// out of valid columns" (that already-invalid range doesn't reliably appear here) - it must be
+// told explicitly, via numBoundaryKeyColumns, how many leading columns actually define a reduce
+// group, and ignore everything past that. Comparing the tiebreaker as a real bound column would
+// silently split a reduce group in half whenever a task cut lands between two physical rows that
+// share a reduce key but differ in tiebreaker (e.g. a join's build-side row vs. its probe-side
+// rows) - each side would look like it's on the "wrong side" of the other's boundary.
 int CompareRowToBoundaryPrefix(
     TStringBuf rowBlob,
     const TRowIndexMarkup& row,
     TStringBuf boundaryBlob,
     const TRowIndexMarkup& boundaryMarkup,
-    const std::vector<ESortOrder>& sortOrders
+    const std::vector<ESortOrder>& sortOrders,
+    size_t numBoundaryKeyColumns
 ) {
-    for (ui64 colIdx = 0; colIdx + 1 < boundaryMarkup.size(); ++colIdx) {
+    const size_t limit = std::min<size_t>(numBoundaryKeyColumns, boundaryMarkup.empty() ? 0 : boundaryMarkup.size() - 1);
+    for (ui64 colIdx = 0; colIdx < limit; ++colIdx) {
         const auto& boundaryRange = boundaryMarkup[colIdx];
         if (!boundaryRange.IsValid()) {
             // Boundary doesn't encode this column (or any further one, since it's a prefix) -
@@ -204,7 +212,8 @@ bool TTableDataServiceBlockIterator::RowInKeyBounds(const TString& blob, const T
             row,
             FirstBoundary_->Row,
             FirstBoundary_->Markup,
-            SortOrders_
+            SortOrders_,
+            NumBoundaryKeyColumns_
         );
         if (c < 0) { // if row < first boundary
             return false;
@@ -218,7 +227,8 @@ bool TTableDataServiceBlockIterator::RowInKeyBounds(const TString& blob, const T
             row,
             LastBoundary_->Row,
             LastBoundary_->Markup,
-            SortOrders_
+            SortOrders_,
+            NumBoundaryKeyColumns_
         );
         if (c > 0) { // if row > last boundary
             return false;
diff --git a/yt/yql/providers/yt/fmr/utils/yson_block_iterator/impl/yql_yt_yson_tds_block_iterator.h b/yt/yql/providers/yt/fmr/utils/yson_block_iterator/impl/yql_yt_yson_tds_block_iterator.h
index 4ab202869fc..8f661e5ec01 100644
--- a/yt/yql/providers/yt/fmr/utils/yson_block_iterator/impl/yql_yt_yson_tds_block_iterator.h
+++ b/yt/yql/providers/yt/fmr/utils/yson_block_iterator/impl/yql_yt_yson_tds_block_iterator.h
@@ -27,8 +27,14 @@ public:
         TMaybe<bool> isLastRowKeysInclusive = Nothing(),
         TMaybe<TString> firstRowKeys = Nothing(),
         TMaybe<TString> lastRowKeys = Nothing(),
-        ui64 readAheadChunks = 4
-
+        ui64 readAheadChunks = 4,
+        // How many leading keyColumns actually define a reduce group (e.g. _yql_key_hash +
+        // reduceBy, excluding a join's _yql_sort tiebreaker). Boundary comparisons stop after
+        // this many columns instead of running to the end of keyColumns - see the comment on
+        // CompareRowToBoundaryPrefix for why relying on the boundary blob happening to omit
+        // trailing columns is not safe. Defaults to comparing every column in keyColumns, which
+        // is correct whenever keyColumns has no trailing tiebreaker (e.g. non-reduce contexts).
+        TMaybe<size_t> numBoundaryKeyColumns = Nothing()
     );
 
     ~TTableDataServiceBlockIterator() final;
@@ -73,6 +79,7 @@ private:
     std::vector<TString> GroupNamesToRead_;
 
     ui64 ReadAheadChunks_ = 4;
+    const size_t NumBoundaryKeyColumns_;
     std::deque<TPrefetchEntry> PrefetchQueue_;
 };
 
diff --git a/yt/yt/client/unittests/mock/table_reader.cpp b/yt/yt/client/unittests/mock/table_reader.cpp
index 1e314884241..ef3c44d0bde 100644
--- a/yt/yt/client/unittests/mock/table_reader.cpp
+++ b/yt/yt/client/unittests/mock/table_reader.cpp
@@ -10,7 +10,7 @@ namespace NYT::NApi {
 TMockTableReader::TMockTableReader(NTableClient::TTableSchemaPtr schema)
     : Schema_(std::move(schema))
     , NameTable_(NTableClient::TNameTable::FromSchema(*Schema_))
-{}
+{ }
 
 const NTableClient::TNameTablePtr& TMockTableReader::GetNameTable() const
 {