YQL-16097: add support for pg default values in parser

2 files changed, 38 insertions, 10 deletions

diff --git a/ydb/library/yql/sql/pg/pg_sql.cpp b/ydb/library/yql/sql/pg/pg_sql.cpp
index 1b3e9010db..05b8a5955f 100644
--- a/ydb/library/yql/sql/pg/pg_sql.cpp
+++ b/ydb/library/yql/sql/pg/pg_sql.cpp
@@ -910,11 +910,6 @@ public:
 
     [[nodiscard]]
     TAstNode* ParseInsertStmt(const InsertStmt* value) {
-        if (!value->selectStmt) {
-            AddError("InsertStmt: expected Select");
-            return nullptr;
-        }
-
         if (value->onConflictClause) {
             AddError("InsertStmt: not supported onConflictClause");
             return nullptr;
@@ -952,16 +947,15 @@ public:
             }
         }
 
-        auto select = ParseSelectStmt(CAST_NODE(SelectStmt, value->selectStmt), true, targetColumns);
+        const auto select = (value->selectStmt) 
+            ? ParseSelectStmt(CAST_NODE(SelectStmt, value->selectStmt), true, targetColumns)
+            : L(A("Void"));
         if (!select) {
             return nullptr;
         }
 
-        auto insertMode = (ProviderToInsertModeMap.contains(Provider))
-            ? ProviderToInsertModeMap.at(Provider)
-            : "append";
+        const auto writeOptions = BuildWriteOptions(value);
 
-        auto writeOptions = QL(QL(QA("mode"), QA(insertMode)));
         Statements.push_back(L(
             A("let"),
             A("world"),
@@ -1225,6 +1219,21 @@ private:
         return QVL(options.data(), options.size());
     }
 
+    TAstNode* BuildWriteOptions(const InsertStmt* value) {
+        std::vector<TAstNode*> options;
+
+        const auto insertMode = (ProviderToInsertModeMap.contains(Provider))
+            ? ProviderToInsertModeMap.at(Provider)
+            : "append";
+        options.push_back(QL(QA("mode"), QA(insertMode)));
+
+        if (!value->selectStmt) {
+            options.push_back(QL(QA("default_values")));
+        }
+
+        return QVL(options.data(), options.size());
+    }
+
 public:
     [[nodiscard]]
     TAstNode* ParseCreateStmt(const CreateStmt* value) {
diff --git a/ydb/library/yql/sql/pg/pg_sql_ut.cpp b/ydb/library/yql/sql/pg/pg_sql_ut.cpp
index 87841b071a..4aca0741c8 100644
--- a/ydb/library/yql/sql/pg/pg_sql_ut.cpp
+++ b/ydb/library/yql/sql/pg/pg_sql_ut.cpp
@@ -72,6 +72,25 @@ Y_UNIT_TEST_SUITE(PgSqlParsingOnly) {
         res.Root->PrintTo(Cerr);
     }
 
+    Y_UNIT_TEST(InsertStmt_DefaultValues) {
+        auto res = PgSqlToYql("INSERT INTO plato.Input DEFAULT VALUES");
+        UNIT_ASSERT(res.Root);
+
+        const NYql::TAstNode* writeNode = nullptr;
+        VisitAstNodes(*res.Root, [&writeNode] (const NYql::TAstNode& node) {
+            const bool isWriteNode = node.IsList() && node.GetChildrenCount() > 0 
+                && node.GetChild(0)->IsAtom() && node.GetChild(0)->GetContent() == "Write!";
+            if (isWriteNode) {
+                writeNode = &node;
+            }
+        });
+
+        UNIT_ASSERT(writeNode);
+        UNIT_ASSERT(writeNode->GetChildrenCount() > 5);
+        const auto optionsQListNode = writeNode->GetChild(5);
+        UNIT_ASSERT(optionsQListNode->ToString().Contains("'default_values"));
+    }
+
     Y_UNIT_TEST(DeleteStmt) {
         auto res = PgSqlToYql("DELETE FROM plato.Input");
         UNIT_ASSERT(res.Root);