Merge pull request #10207 from ClickHouse/fix-join-constants

Fix column names of constants inside JOIN.

src/Interpreters/RequiredSourceColumnsVisitor.cpp

@@ -88,12 +88,14 @@ void RequiredSourceColumnsMatcher::visit(const ASTPtr & ast, Data & data)
         visit(*t, ast, data);
         return;
     }
+
     if (auto * t = ast->as<ASTSelectQuery>())
     {
         data.addTableAliasIfAny(*ast);
         visit(*t, ast, data);
         return;
     }
+
     if (ast->as<ASTSubquery>())
     {
         data.addTableAliasIfAny(*ast);

src/Interpreters/TableJoin.cpp

@@ -5,6 +5,8 @@
 #include <Core/Settings.h>
 #include <Core/Block.h>
 
+#include <Common/StringUtils/StringUtils.h>
+
 #include <DataTypes/DataTypeNullable.h>
 
 
@@ -79,7 +81,9 @@ void TableJoin::deduplicateAndQualifyColumnNames(const NameSet & left_table_colu
         dedup_columns.push_back(column);
         auto & inserted = dedup_columns.back();
 
-        if (left_table_columns.count(column.name))
+        /// Also qualify unusual column names - that does not look like identifiers.
+
+        if (left_table_columns.count(column.name) || !isValidIdentifierBegin(column.name.at(0)))
             inserted.name = right_table_prefix + column.name;
 
         original_names[inserted.name] = column.name;

src/Interpreters/TranslateQualifiedNamesVisitor.cpp

@@ -5,6 +5,7 @@
 #include <Interpreters/AsteriskSemantic.h>
 
 #include <Common/typeid_cast.h>
+#include <Common/StringUtils/StringUtils.h>
 #include <Core/Names.h>
 
 #include <Parsers/ASTIdentifier.h>
@@ -107,8 +108,9 @@ void TranslateQualifiedNamesMatcher::visit(ASTIdentifier & identifier, ASTPtr &,
             IdentifierSemantic::setMembership(identifier, table_pos);
 
             /// In case if column from the joined table are in source columns, change it's name to qualified.
+            /// Also always leave unusual identifiers qualified.
             auto & table = data.tables[table_pos].table;
-            if (table_pos && data.hasColumn(short_name))
+            if (table_pos && (data.hasColumn(short_name) || !isValidIdentifierBegin(short_name.at(0))))
                 IdentifierSemantic::setColumnLongName(identifier, table);
             else
                 IdentifierSemantic::setColumnShortName(identifier, table);
@@ -128,7 +130,7 @@ void TranslateQualifiedNamesMatcher::visit(ASTFunction & node, const ASTPtr &, D
         func_arguments->children.clear();
 }
 
-void TranslateQualifiedNamesMatcher::visit(const ASTQualifiedAsterisk & , const ASTPtr & ast, Data & data)
+void TranslateQualifiedNamesMatcher::visit(const ASTQualifiedAsterisk &, const ASTPtr & ast, Data & data)
 {
     if (ast->children.size() != 1)
         throw Exception("Logical error: qualified asterisk must have exactly one child", ErrorCodes::LOGICAL_ERROR);

tests/queries/0_stateless/01120_join_constants.reference

@@ -0,0 +1,2 @@
+1	hello	1	world	world	1
+2	hello	0		world	1

tests/queries/0_stateless/01120_join_constants.sql

@@ -0,0 +1,17 @@
+SELECT
+    t1.*,
+    t2.*,
+    'world',
+    isConstant('world')
+FROM
+(
+    SELECT
+        arrayJoin([1, 2]) AS k,
+        'hello'
+) AS t1
+LEFT JOIN
+(
+    SELECT
+        arrayJoin([1, 3]) AS k,
+        'world'
+) AS t2 ON t1.k = t2.k;

tests/queries/bugs/join_constants_on.sql

@@ -0,0 +1,2 @@
+select cast(1, 'UInt8') from (select arrayJoin([1, 2]) as a) t1 left join (select 1 as b) t2 on b = ignore('UInt8');
+select isConstant('UInt8'), toFixedString('hello', toUInt8(substring('UInt8', 5, 1))) from (select arrayJoin([1, 2]) as a) t1 left join (select 1 as b) t2 on b = ignore('UInt8');