Revert "Allow DISCARD in SUBQUERY"

This reverts commit ed52aaa7c82c291103226fea40649ca7b339f461, reversing
changes made to c6884232d88ff395369713a4983fe964bc757ab9.

6 files changed, 10 insertions, 49 deletions

diff --git a/ydb/library/yql/sql/v1/node.cpp b/ydb/library/yql/sql/v1/node.cpp
index 79c92301dc..c13a6a2e6b 100644
--- a/ydb/library/yql/sql/v1/node.cpp
+++ b/ydb/library/yql/sql/v1/node.cpp
@@ -278,10 +278,6 @@ bool INode::IsSelect() const {
     return false;
 }
 
-bool INode::HasSelectResult() const {
-    return false;
-}
-
 const TString* INode::FuncName() const {
     return nullptr;
 }
diff --git a/ydb/library/yql/sql/v1/node.h b/ydb/library/yql/sql/v1/node.h
index f79a2d7d80..be900e88f9 100644
--- a/ydb/library/yql/sql/v1/node.h
+++ b/ydb/library/yql/sql/v1/node.h
@@ -174,7 +174,6 @@ namespace NSQLTranslationV1 {
         void UseAsInner();
         virtual bool UsedSubquery() const;
         virtual bool IsSelect() const;
-        virtual bool HasSelectResult() const;
         virtual const TString* FuncName() const;
         virtual const TString* ModuleName() const;
         virtual bool HasSkip() const;
diff --git a/ydb/library/yql/sql/v1/select.cpp b/ydb/library/yql/sql/v1/select.cpp
index d7b1e57c31..79663eca9f 100644
--- a/ydb/library/yql/sql/v1/select.cpp
+++ b/ydb/library/yql/sql/v1/select.cpp
@@ -1160,10 +1160,6 @@ public:
         return Settings;
     }
 
-    bool HasSelectResult() const final {
-        return !Settings.Discard;
-    }
-
     TPtr DoClone() const final {
         return new TReduceSource(Pos, Mode, Source->CloneSource(), CloneContainer(OrderBy),
             CloneContainer(Keys), CloneContainer(Args), SafeClone(Udf), SafeClone(Having), Settings,
@@ -1380,10 +1376,6 @@ public:
         return Settings;
     }
 
-    bool HasSelectResult() const override {
-        return !Settings.Discard;
-    }
-
     TNodePtr DoClone() const final {
         auto newSource = MakeIntrusive<TCompositeSelect>(Pos, Source->CloneSource(), OriginalSource->CloneSource(), Settings);
         newSource->SetSubselects(CloneContainer(Subselects), CloneContainer(Grouping), CloneContainer(GroupByExpr));
@@ -1756,10 +1748,6 @@ public:
         return true;
     }
 
-    bool HasSelectResult() const override {
-        return !Settings.Discard;
-    }
-
     bool IsStream() const override {
         return Source->IsStream();
     }
@@ -2370,10 +2358,6 @@ public:
         return false;
     }
 
-    bool HasSelectResult() const override {
-        return !Settings.Discard;
-    }
-
     bool IsStream() const override {
         return Source->IsStream();
     }
@@ -2678,10 +2662,6 @@ public:
         return true;
     }
 
-    bool HasSelectResult() const override {
-        return !Settings.Discard;
-    }
-
     TWriteSettings GetWriteSettings() const override {
         return Settings;
     }
@@ -2876,10 +2856,6 @@ public:
         return Source->IsSelect();
     }
 
-    bool HasSelectResult() const override {
-        return Source->HasSelectResult();
-    }
-
     TPtr DoClone() const final {
         return MakeIntrusive<TSelect>(Pos, Source->CloneSource(), SafeClone(SkipTake));
     }
@@ -2915,10 +2891,6 @@ public:
         return true;
     }
 
-    bool HasSelectResult() const override {
-        return Source->HasSelectResult();
-    }
-
     bool DoInit(TContext& ctx, ISource* src) override {
         if (!Source->Init(ctx, src)) {
             return false;
@@ -2991,7 +2963,7 @@ public:
             return false;
         }
         node = L(node, Y("let", "output", output));
-        if (WriteResult || writeSettings.Discard) {
+        if (WriteResult) {
             if (EOrderKind::None == Source->GetOrderKind() && ctx.UseUnordered(*Source)) {
                 node = L(node, Y("let", "output", Y("Unordered", "output")));
             }
diff --git a/ydb/library/yql/sql/v1/sql_query.cpp b/ydb/library/yql/sql/v1/sql_query.cpp
index 40cd4a5aba..54ea1f4c73 100644
--- a/ydb/library/yql/sql/v1/sql_query.cpp
+++ b/ydb/library/yql/sql/v1/sql_query.cpp
@@ -2181,22 +2181,19 @@ TNodePtr TSqlQuery::Build(const TSQLv1ParserAST& ast) {
     }
 
     ui32 topLevelSelects = 0;
-    bool hasTailOps = false;
     for (auto& block : blocks) {
-        if (block->HasSelectResult()) {
+        if (block->IsSelect()) {
             ++topLevelSelects;
-        } else if (topLevelSelects) {
-            hasTailOps = true;
         }
     }
 
-    if ((Mode == NSQLTranslation::ESqlMode::SUBQUERY || Mode == NSQLTranslation::ESqlMode::LIMITED_VIEW) && (topLevelSelects != 1 || hasTailOps)) {
-        Error() << "Strictly one select/process/reduce statement is expected at the end of "
+    if ((Mode == NSQLTranslation::ESqlMode::SUBQUERY || Mode == NSQLTranslation::ESqlMode::LIMITED_VIEW) && topLevelSelects != 1) {
+        Error() << "Strictly one select/process/reduce statement must be used in the "
             << (Mode == NSQLTranslation::ESqlMode::LIMITED_VIEW ? "view" : "subquery");
         return nullptr;
     }
 
-     if (!Ctx.PragmaAutoCommit && Ctx.Settings.EndOfQueryCommit && IsQueryMode(Mode)) {
+    if (!Ctx.PragmaAutoCommit && Ctx.Settings.EndOfQueryCommit && IsQueryMode(Mode)) {
         AddStatementToBlocks(blocks, BuildCommitClusters(Ctx.Pos()));
     }
 
diff --git a/ydb/library/yql/sql/v1/sql_select.cpp b/ydb/library/yql/sql/v1/sql_select.cpp
index d2f4a87075..b525ca0cbf 100644
--- a/ydb/library/yql/sql/v1/sql_select.cpp
+++ b/ydb/library/yql/sql/v1/sql_select.cpp
@@ -1211,8 +1211,8 @@ TSqlSelect::TSelectKindResult TSqlSelect::SelectKind(const TRule_select_kind& no
 {
     const bool discard = node.HasBlock1();
     const bool hasLabel = node.HasBlock3();
-    if (hasLabel && (Mode == NSQLTranslation::ESqlMode::LIMITED_VIEW || Mode == NSQLTranslation::ESqlMode::SUBQUERY)) {
-        Ctx.Error() << "INTO RESULT is not allowed in current mode";
+    if ((discard || hasLabel) && (Mode == NSQLTranslation::ESqlMode::LIMITED_VIEW || Mode == NSQLTranslation::ESqlMode::SUBQUERY)) {
+        Ctx.Error() << "DISCARD and INTO RESULT are not allowed in current mode";
         return {};
     }
 
diff --git a/ydb/library/yql/sql/v1/sql_translation.cpp b/ydb/library/yql/sql/v1/sql_translation.cpp
index 325bacc944..aaf4b53958 100644
--- a/ydb/library/yql/sql/v1/sql_translation.cpp
+++ b/ydb/library/yql/sql/v1/sql_translation.cpp
@@ -3970,17 +3970,14 @@ bool TSqlTranslation::DefineActionOrSubqueryStatement(const TRule_define_action_
     const bool hasValidBody = DefineActionOrSubqueryBody(query, innerBlocks, stmt.GetRule_define_action_or_subquery_body8());
 
     ui32 topLevelSelects = 0;
-    bool hasTailOps = false;
     for (auto& block : innerBlocks) {
-        if (block->HasSelectResult()) {
+        if (block->IsSelect()) {
             ++topLevelSelects;
-        } else if (topLevelSelects) {
-            hasTailOps = true;
         }
     }
 
-    if (isSubquery && (topLevelSelects != 1 || hasTailOps)) {
-        Error() << "Strictly one select/process/reduce statement is expected at the end of subquery";
+    if (isSubquery && topLevelSelects != 1) {
+        Error() << "Strictly one select/process/reduce statement must be used in the subquery, got: " << topLevelSelects;
         return false;
     }