Merge pull request #57662 from ClickHouse/vdimir/analyzer_join_on_tru…

…e_nullable

Analyzer: Fix JOIN ON true with join_use_nulls

src/Planner/PlannerJoinTree.cpp

@@ -988,18 +988,7 @@ JoinTreeQueryPlan buildQueryPlanForJoinNode(const QueryTreeNodePtr & join_table_
     if (join_strictness == JoinStrictness::All || join_strictness == JoinStrictness::Semi  || join_strictness == JoinStrictness::Anti)
         join_constant = tryExtractConstantFromJoinNode(join_table_expression);
 
-    if (join_constant)
-    {
-        /** If there is JOIN with always true constant, we transform it to cross.
-          * If there is JOIN with always false constant, we do not process JOIN keys.
-          * It is expected by join algorithm to handle such case.
-          *
-          * Example: SELECT * FROM test_table AS t1 INNER JOIN test_table AS t2 ON 1;
-          */
-        if (*join_constant)
-            join_kind = JoinKind::Cross;
-    }
-    else if (join_node.isOnJoinExpression())
+    if (!join_constant && join_node.isOnJoinExpression())
     {
         join_clauses_and_actions = buildJoinClausesAndActions(left_plan_output_columns,
             right_plan_output_columns,
@@ -1079,7 +1068,6 @@ JoinTreeQueryPlan buildQueryPlanForJoinNode(const QueryTreeNodePtr & join_table_
     const auto & query_context = planner_context->getQueryContext();
     const auto & settings = query_context->getSettingsRef();
 
-    bool join_use_nulls = settings.join_use_nulls;
     auto to_nullable_function = FunctionFactory::instance().get("toNullable", query_context);
 
     auto join_cast_plan_columns_to_nullable = [&](QueryPlan & plan_to_add_cast)
@@ -1105,7 +1093,7 @@ JoinTreeQueryPlan buildQueryPlanForJoinNode(const QueryTreeNodePtr & join_table_
         plan_to_add_cast.addStep(std::move(cast_join_columns_step));
     };
 
-    if (join_use_nulls)
+    if (settings.join_use_nulls)
     {
         if (isFull(join_kind))
         {
@@ -1124,6 +1112,18 @@ JoinTreeQueryPlan buildQueryPlanForJoinNode(const QueryTreeNodePtr & join_table_
 
     auto table_join = std::make_shared<TableJoin>(settings, query_context->getGlobalTemporaryVolume());
     table_join->getTableJoin() = join_node.toASTTableJoin()->as<ASTTableJoin &>();
+
+    if (join_constant)
+    {
+        /** If there is JOIN with always true constant, we transform it to cross.
+          * If there is JOIN with always false constant, we do not process JOIN keys.
+          * It is expected by join algorithm to handle such case.
+          *
+          * Example: SELECT * FROM test_table AS t1 INNER JOIN test_table AS t2 ON 1;
+          */
+        if (*join_constant)
+            join_kind = JoinKind::Cross;
+    }
     table_join->getTableJoin().kind = join_kind;
 
     if (join_kind == JoinKind::Comma)

tests/queries/0_stateless/02000_join_on_const.reference

@@ -65,3 +65,7 @@ SELECT * FROM (SELECT 1 as a) as t1 FULL JOIN  ( SELECT ('b', 256) as b ) AS t2
 SELECT * FROM (SELECT 1 as a) as t1 SEMI JOIN  ( SELECT ('b', 256) as b ) AS t2 ON NULL;
 SELECT * FROM (SELECT 1 as a) as t1 ANTI JOIN  ( SELECT ('b', 256) as b ) AS t2 ON NULL;
 1	('',0)
+2
+4	2	Nullable(UInt64)	UInt8
+4	2	UInt64	Nullable(UInt8)
+4	2	Nullable(UInt64)	Nullable(UInt8)

tests/queries/0_stateless/02000_join_on_const.sql

@@ -90,6 +90,31 @@ SELECT * FROM (SELECT 1 as a) as t1 ANTI JOIN  ( SELECT ('b', 256) as b ) AS t2
 
 -- { echoOff }
 
+SELECT a + 1
+FROM (SELECT 1 as x) as t1
+LEFT JOIN ( SELECT 1 AS a ) AS t2
+ON TRUE
+SETTINGS allow_experimental_analyzer=1, join_use_nulls=1;
+
+SELECT a + 1, x + 1, toTypeName(a), toTypeName(x)
+FROM (SELECT 1 as x) as t1
+LEFT JOIN ( SELECT sum(number) as a from numbers(3) GROUP BY NULL) AS t2
+ON TRUE
+SETTINGS allow_experimental_analyzer=1, join_use_nulls=1;
+
+SELECT a + 1, x + 1, toTypeName(a), toTypeName(x)
+FROM (SELECT 1 as x) as t1
+RIGHT JOIN ( SELECT sum(number) as a from numbers(3) GROUP BY NULL) AS t2
+ON TRUE
+SETTINGS allow_experimental_analyzer=1, join_use_nulls=1;
+
+SELECT a + 1, x + 1, toTypeName(a), toTypeName(x)
+FROM (SELECT 1 as x) as t1
+FULL JOIN ( SELECT sum(number) as a from numbers(3) GROUP BY NULL) AS t2
+ON TRUE
+SETTINGS allow_experimental_analyzer=1, join_use_nulls=1;
+
+
 DROP TABLE IF EXISTS t1;
 DROP TABLE IF EXISTS t2;