From 3b40099578b474cc2ba26980148c666edb55c3c5 Mon Sep 17 00:00:00 2001
From: feng lv <fenglv15@mails.ucas.ac.cn>
Date: Wed, 17 Feb 2021 08:26:52 +0000
Subject: [PATCH] fix subquery with limit

---
 src/Interpreters/InterpreterSelectQuery.cpp     | 17 +++++++++++++++--
 .../01720_union_distinct_with_limit.reference   |  1 +
 .../01720_union_distinct_with_limit.sql         |  8 ++++++++
 3 files changed, 24 insertions(+), 2 deletions(-)
 create mode 100644 tests/queries/0_stateless/01720_union_distinct_with_limit.reference
 create mode 100644 tests/queries/0_stateless/01720_union_distinct_with_limit.sql

diff --git a/src/Interpreters/InterpreterSelectQuery.cpp b/src/Interpreters/InterpreterSelectQuery.cpp
index 84de6fa4e6..a325a8d332 100644
--- a/src/Interpreters/InterpreterSelectQuery.cpp
+++ b/src/Interpreters/InterpreterSelectQuery.cpp
@@ -784,9 +784,22 @@ static bool hasWithTotalsInAnySubqueryInFromClause(const ASTSelectQuery & query)
     {
         if (const auto * ast_union = query_table->as<ASTSelectWithUnionQuery>())
         {
+            ///NOTE: Child of subquery can be ASTSelectWithUnionQuery or ASTSelectQuery,
+            /// and after normalization, the height of the AST tree is at most 2
             for (const auto & elem : ast_union->list_of_selects->children)
-                if (hasWithTotalsInAnySubqueryInFromClause(elem->as<ASTSelectQuery &>()))
-                    return true;
+            {
+                if (const auto * child_union = elem->as<ASTSelectWithUnionQuery>())
+                {
+                    for (const auto & child_elem : child_union->list_of_selects->children)
+                        if (hasWithTotalsInAnySubqueryInFromClause(child_elem->as<ASTSelectQuery &>()))
+                            return true;
+                }
+                else
+                {
+                    if (hasWithTotalsInAnySubqueryInFromClause(elem->as<ASTSelectQuery &>()))
+                        return true;
+                }
+            }
         }
     }
 
diff --git a/tests/queries/0_stateless/01720_union_distinct_with_limit.reference b/tests/queries/0_stateless/01720_union_distinct_with_limit.reference
new file mode 100644
index 0000000000..d00491fd7e
--- /dev/null
+++ b/tests/queries/0_stateless/01720_union_distinct_with_limit.reference
@@ -0,0 +1 @@
+1
diff --git a/tests/queries/0_stateless/01720_union_distinct_with_limit.sql b/tests/queries/0_stateless/01720_union_distinct_with_limit.sql
new file mode 100644
index 0000000000..9fc5b3eafd
--- /dev/null
+++ b/tests/queries/0_stateless/01720_union_distinct_with_limit.sql
@@ -0,0 +1,8 @@
+SELECT x
+FROM
+(
+    SELECT 1 AS x
+    UNION DISTINCT
+    SELECT 1
+)
+LIMIT 1;
-- 
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