Avoid alias duplicates in PASTE JOIN and fix aliases requirement

src/Analyzer/Passes/QueryAnalysisPass.cpp

@@ -1207,6 +1207,8 @@ class QueryAnalyzer
 
     static void validateJoinTableExpressionWithoutAlias(const QueryTreeNodePtr & join_node, const QueryTreeNodePtr & table_expression_node, IdentifierResolveScope & scope);
 
+    static void checkDuplicateTableNamesOrAlias(QueryTreeNodePtr & join_node, QueryTreeNodePtr & left_table_expr, QueryTreeNodePtr & right_table_expr, IdentifierResolveScope & scope);
+
     static std::pair<bool, UInt64> recursivelyCollectMaxOrdinaryExpressions(QueryTreeNodePtr & node, QueryTreeNodes & into);
 
     static void expandGroupByAll(QueryNode & query_tree_node_typed);
@@ -2243,6 +2245,9 @@ void QueryAnalyzer::validateJoinTableExpressionWithoutAlias(const QueryTreeNodeP
     if (table_expression_has_alias)
         return;
 
+    if (join_node->as<JoinNode &>().getKind() == JoinKind::Paste)
+        return;
+
     auto * query_node = table_expression_node->as<QueryNode>();
     auto * union_node = table_expression_node->as<UnionNode>();
     if ((query_node && !query_node->getCTEName().empty()) || (union_node && !union_node->getCTEName().empty()))
@@ -6777,6 +6782,34 @@ void QueryAnalyzer::resolveArrayJoin(QueryTreeNodePtr & array_join_node, Identif
     }
 }
 
+void QueryAnalyzer::checkDuplicateTableNamesOrAlias(QueryTreeNodePtr & join_node, QueryTreeNodePtr & left_table_expr, QueryTreeNodePtr & right_table_expr, IdentifierResolveScope & scope)
+{
+    if (!scope.context->getSettingsRef().joined_subquery_requires_alias)
+        return;
+
+    if (join_node->as<JoinNode &>().getKind() != JoinKind::Paste)
+        return;
+
+    Names column_names;
+    auto * left_node = left_table_expr->as<QueryNode>();
+    auto * right_node = right_table_expr->as<QueryNode>();
+
+    for (const auto & name_and_type : left_node->getProjectionColumns())
+        column_names.push_back(name_and_type.name);
+    for (const auto & name_and_type : right_node->getProjectionColumns())
+        column_names.push_back(name_and_type.name);
+
+    if (column_names.empty())
+        throw Exception(ErrorCodes::LOGICAL_ERROR, "Names of projection columns cannot be empty");
+
+    std::sort(column_names.begin(), column_names.end());
+    for (size_t i = 0; i < column_names.size() - 1; i++) // Check if there is not any duplicates because it will lead to broken result
+        if (column_names[i] == column_names[i+1])
+            throw Exception(ErrorCodes::BAD_ARGUMENTS,
+                            "Name of columns and aliases should be unique for this query (you can add/change aliases so they will not be duplicated)"
+                            "While processing '{}'", join_node->formatASTForErrorMessage());
+}
+
 /// Resolve join node in scope
 void QueryAnalyzer::resolveJoin(QueryTreeNodePtr & join_node, IdentifierResolveScope & scope, QueryExpressionsAliasVisitor & expressions_visitor)
 {
@@ -6788,6 +6821,9 @@ void QueryAnalyzer::resolveJoin(QueryTreeNodePtr & join_node, IdentifierResolveS
     resolveQueryJoinTreeNode(join_node_typed.getRightTableExpression(), scope, expressions_visitor);
     validateJoinTableExpressionWithoutAlias(join_node, join_node_typed.getRightTableExpression(), scope);
 
+    if (!join_node_typed.getLeftTableExpression()->hasAlias() && !join_node_typed.getRightTableExpression()->hasAlias())
+        checkDuplicateTableNamesOrAlias(join_node, join_node_typed.getLeftTableExpression(), join_node_typed.getRightTableExpression(), scope);
+
     if (join_node_typed.isOnJoinExpression())
     {
         expressions_visitor.visit(join_node_typed.getJoinExpression());

src/Parsers/ExpressionElementParsers.cpp

@@ -1451,6 +1451,7 @@ const char * ParserAlias::restricted_keywords[] =
     "ASOF",
     "BETWEEN",
     "CROSS",
+    "PASTE",
     "FINAL",
     "FORMAT",
     "FROM",

tests/queries/0_stateless/02933_paste_join.reference

@@ -82,3 +82,9 @@ UInt64
 7	2
 8	1
 9	0
+0	0
+1	1
+2	2
+3	3
+4	4
+5	5

tests/queries/0_stateless/02933_paste_join.sql

@@ -1,6 +1,6 @@
 select * from (SELECT number as a FROM numbers(10)) t1 PASTE JOIN (select number as a from numbers(10)) t2;
 select * from (SELECT number as a FROM numbers(10)) t1 PASTE JOIN (select number as a from numbers(10) order by a desc) t2;
-create table if not exists test (num UInt64) engine=Memory;
+create table if not exists test (number UInt64) engine=Memory;
 insert into test select number from numbers(6);
 insert into test select number from numbers(5);
 SELECT * FROM (SELECT 1) t1 PASTE JOIN (SELECT 2) SETTINGS joined_subquery_requires_alias=0;
@@ -35,3 +35,8 @@ SET max_threads = 2;
 select * from (SELECT number as a FROM numbers_mt(10)) t1 PASTE JOIN (select number as a from numbers(10) ORDER BY a DESC) t2 SETTINGS max_block_size=10;
 select * from (SELECT number as a FROM numbers(10)) t1 ANY PASTE JOIN (select number as a from numbers(10)) t2; -- { clientError SYNTAX_ERROR }
 select * from (SELECT number as a FROM numbers(10)) t1 ALL PASTE JOIN (select number as a from numbers(10)) t2; -- { clientError SYNTAX_ERROR }
+
+SELECT * FROM (SELECT number FROM test) PASTE JOIN (SELECT number FROM numbers(10) ORDER BY number DESC ) SETTINGS joined_subquery_requires_alias = 1, allow_experimental_analyzer = 1; -- { serverError BAD_ARGUMENTS }
+TRUNCATE TABLE test;
+INSERT INTO test SELECT number from numbers(6);
+SELECT * FROM (SELECT number FROM test) PASTE JOIN (SELECT number FROM numbers(6) ORDER BY number) SETTINGS joined_subquery_requires_alias = 0;