Bug #20191: getTableName gives wrong or inconsistent result when using VIEWs

When compiling GROUP BY Item_ref instances are dereferenced in 
setup_copy_fields(), i.e. replaced with the corresponding Item_field 
(if they point to one) or Item_copy_string for the other cases.
Since the Item_ref (in the Item_field case) is no longer used the information
about the aliases stored in it is lost.   
Fixed by preserving the column, table and DB alias on dereferencing Item_ref


mysql-test/r/metadata.result:
  Bug #20191: getTableName gives wrong or inconsistent result when using VIEWs
   - test case
mysql-test/t/metadata.test:
  Bug #20191: getTableName gives wrong or inconsistent result when using VIEWs
   - test case
sql/item.cc:
  Bug #20191: getTableName gives wrong or inconsistent result when using VIEWs
   - use the table and db name to fill up the metadata for columns
sql/sql_select.cc:
  Bug #20191: getTableName gives wrong or inconsistent result when using VIEWs
   - preserve the field, table and DB name on dereferencing an Item_ref

2 files changed, 53 insertions, 0 deletions

diff --git a/mysql-test/r/metadata.result b/mysql-test/r/metadata.result
index 50b0b6ae294..34e961395c4 100644
--- a/mysql-test/r/metadata.result
+++ b/mysql-test/r/metadata.result
@@ -96,3 +96,37 @@ i
 2
 affected rows: 1
 affected rows: 0
+create table t1 (id int(10));
+insert into t1 values (1);
+CREATE  VIEW v1 AS select t1.id as id from t1;
+CREATE  VIEW v2 AS select t1.id as renamed from t1;
+CREATE  VIEW v3 AS select t1.id + 12 as renamed from t1;
+select * from v1 group by id limit 1;
+Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
+def	test	t1	v1	id	id	3	10	1	Y	32768	0	63
+id
+1
+select * from v1 group by id limit 0;
+Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
+def	test	t1	v1	id	id	3	10	0	Y	32768	0	63
+id
+select * from v1 where id=1000 group by id;
+Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
+def	test	t1	v1	id	id	3	10	0	Y	32768	0	63
+id
+select * from v1 where id=1 group by id;
+Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
+def	test	t1	v1	id	id	3	10	1	Y	32768	0	63
+id
+1
+select * from v2 where renamed=1 group by renamed;
+Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
+def	test	t1	v2	id	renamed	3	10	1	Y	32768	0	63
+renamed
+1
+select * from v3 where renamed=1 group by renamed;
+Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
+def			v3		renamed	8	12	0	Y	32896	0	63
+renamed
+drop table t1;
+drop view v1,v2,v3;
diff --git a/mysql-test/t/metadata.test b/mysql-test/t/metadata.test
index 65338448555..a6ebfdc14c1 100644
--- a/mysql-test/t/metadata.test
+++ b/mysql-test/t/metadata.test
@@ -61,4 +61,23 @@ drop table t1;//
 delimiter ;//
 --disable_info
 
+#
+# Bug #20191: getTableName gives wrong or inconsistent result when using VIEWs
+#
+--enable_metadata
+create table t1 (id int(10));
+insert into t1 values (1);
+CREATE  VIEW v1 AS select t1.id as id from t1;
+CREATE  VIEW v2 AS select t1.id as renamed from t1;
+CREATE  VIEW v3 AS select t1.id + 12 as renamed from t1;
+select * from v1 group by id limit 1;
+select * from v1 group by id limit 0;
+select * from v1 where id=1000 group by id;
+select * from v1 where id=1 group by id;
+select * from v2 where renamed=1 group by renamed;
+select * from v3 where renamed=1 group by renamed;
+drop table t1;
+drop view v1,v2,v3;
+--disable_metadata
+
 # End of 4.1 tests