Warning on join hints for cross join (#3644)

2 files changed, 19 insertions, 0 deletions

diff --git a/ydb/library/yql/sql/v1/sql_select.cpp b/ydb/library/yql/sql/v1/sql_select.cpp
index f63d6d963aa..2700ba0e99f 100644
--- a/ydb/library/yql/sql/v1/sql_select.cpp
+++ b/ydb/library/yql/sql/v1/sql_select.cpp
@@ -47,7 +47,10 @@ bool TSqlSelect::JoinOp(ISource* join, const TRule_join_source::TBlock3& block,
                     newStrategy = TJoinLinkSettings::EStrategy::SortedMerge;
                 } else if (canonizedName == "streamlookup") {
                     newStrategy = TJoinLinkSettings::EStrategy::StreamLookup;
+                } else {
+                    Ctx.Warning(hint.Pos, TIssuesIds::YQL_UNUSED_HINT) << "Unsupported join strategy: " << hint.Name;
                 }
+
                 if (TJoinLinkSettings::EStrategy::Default == linkSettings.Strategy) {
                     linkSettings.Strategy = newStrategy;
                 } else if (newStrategy == linkSettings.Strategy) {
@@ -119,6 +122,10 @@ bool TSqlSelect::JoinOp(ISource* join, const TRule_join_source::TBlock3& block,
             joinOp = NormalizeJoinOp(joinOp);
             Ctx.IncrementMonCounter("sql_features", "Join");
             Ctx.IncrementMonCounter("sql_join_operations", joinOp);
+            if (linkSettings.Strategy != TJoinLinkSettings::EStrategy::Default && joinOp == "Cross") {
+                Ctx.Warning(Ctx.Pos(), TIssuesIds::YQL_UNUSED_HINT) << "Non-default join strategy will not be used for CROSS JOIN";
+                linkSettings.Strategy = TJoinLinkSettings::EStrategy::Default;
+            }
 
             TNodePtr joinKeyExpr;
             if (block.HasBlock4()) {
diff --git a/ydb/library/yql/sql/v1/sql_ut.cpp b/ydb/library/yql/sql/v1/sql_ut.cpp
index f34c4b10a2b..70631adffd2 100644
--- a/ydb/library/yql/sql/v1/sql_ut.cpp
+++ b/ydb/library/yql/sql/v1/sql_ut.cpp
@@ -535,6 +535,18 @@ Y_UNIT_TEST_SUITE(SqlParsingOnly) {
         }
     }
 
+    Y_UNIT_TEST(WarnCrossJoinStrategyHint) {
+        NYql::TAstParseResult res = SqlToYql("SELECT * FROM plato.Input AS a CROSS JOIN /*+ merge() */ plato.Input AS b;");
+        UNIT_ASSERT(res.Root);
+        UNIT_ASSERT_STRINGS_EQUAL(res.Issues.ToString(), "<main>:1:32: Warning: Non-default join strategy will not be used for CROSS JOIN, code: 4534\n");
+    }
+
+    Y_UNIT_TEST(WarnUnknownJoinStrategyHint) {
+        NYql::TAstParseResult res = SqlToYql("SELECT * FROM plato.Input AS a JOIN /*+ xmerge() */ plato.Input AS b USING (key);");
+        UNIT_ASSERT(res.Root);
+        UNIT_ASSERT_STRINGS_EQUAL(res.Issues.ToString(), "<main>:1:41: Warning: Unsupported join strategy: xmerge, code: 4534\n");
+    }
+
     Y_UNIT_TEST(ReverseLabels) {
         NYql::TAstParseResult res = SqlToYql("select in.key as subkey, subkey as key from plato.Input as in;");
         UNIT_ASSERT(res.Root);