MDEV-6103 - Adding/removing non-materialized virtual column triggers

            table recreation

Relaxed InnoDB/XtraDB checks to allow online add/drop of
non-materialized virtual columns.

mysql-test/suite/vcol/inc/vcol_non_stored_columns.inc

@@ -160,3 +160,15 @@ select * from t1;
 show create table t1;
 drop table t1;
 
+--echo #
+--echo # MDEV-6103 - Adding/removing non-materialized virtual column triggers
+--echo #             table recreation
+--echo #
+CREATE TABLE t1(a INT);
+INSERT INTO t1 VALUES(1),(1),(1),(1),(1),(1),(1),(1),(1),(1);
+enable_info;
+ALTER TABLE t1 ADD COLUMN b INT AS (a + 1) VIRTUAL;
+ALTER TABLE t1 DROP COLUMN b;
+disable_info;
+CHECK TABLE t1;
+DROP TABLE t1;

mysql-test/suite/vcol/r/vcol_non_stored_columns_innodb.result

@@ -240,3 +240,19 @@ t1	CREATE TABLE `t1` (
   `c` int(11) AS (week(b,1)) VIRTUAL
 ) ENGINE=InnoDB DEFAULT CHARSET=latin1
 drop table t1;
+#
+# MDEV-6103 - Adding/removing non-materialized virtual column triggers
+#             table recreation
+#
+CREATE TABLE t1(a INT);
+INSERT INTO t1 VALUES(1),(1),(1),(1),(1),(1),(1),(1),(1),(1);
+ALTER TABLE t1 ADD COLUMN b INT AS (a + 1) VIRTUAL;
+affected rows: 0
+info: Records: 0  Duplicates: 0  Warnings: 0
+ALTER TABLE t1 DROP COLUMN b;
+affected rows: 0
+info: Records: 0  Duplicates: 0  Warnings: 0
+CHECK TABLE t1;
+Table	Op	Msg_type	Msg_text
+test.t1	check	status	OK
+DROP TABLE t1;

mysql-test/suite/vcol/r/vcol_non_stored_columns_myisam.result

@@ -240,3 +240,19 @@ t1	CREATE TABLE `t1` (
   `c` int(11) AS (week(b,1)) VIRTUAL
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 drop table t1;
+#
+# MDEV-6103 - Adding/removing non-materialized virtual column triggers
+#             table recreation
+#
+CREATE TABLE t1(a INT);
+INSERT INTO t1 VALUES(1),(1),(1),(1),(1),(1),(1),(1),(1),(1);
+ALTER TABLE t1 ADD COLUMN b INT AS (a + 1) VIRTUAL;
+affected rows: 10
+info: Records: 10  Duplicates: 0  Warnings: 0
+ALTER TABLE t1 DROP COLUMN b;
+affected rows: 10
+info: Records: 10  Duplicates: 0  Warnings: 0
+CHECK TABLE t1;
+Table	Op	Msg_type	Msg_text
+test.t1	check	status	OK
+DROP TABLE t1;

storage/innobase/handler/handler0alter.cc

@@ -351,10 +351,14 @@ ha_innobase::check_if_supported_inplace_alter(
 
 	  Don't do online ALTER if mtype/unsigned_flag are wrong.
 	*/
-	for (ulint i = 0; i < table->s->fields; i++) {
+	for (ulint i = 0, icol= 0; i < table->s->fields; i++) {
 		const Field*		field = table->field[i];
-		const dict_col_t*	col = dict_table_get_nth_col(prebuilt->table, i);
+		const dict_col_t*	col = dict_table_get_nth_col(prebuilt->table, icol);
 		ulint		unsigned_flag;
+		if (!field->stored_in_db)
+			continue;
+		icol++;
+
 		if (col->mtype != get_innobase_type_from_mysql_type(&unsigned_flag, field)) {
 
 			DBUG_RETURN(HA_ALTER_INPLACE_NOT_SUPPORTED);

storage/xtradb/handler/handler0alter.cc

@@ -351,10 +351,14 @@ ha_innobase::check_if_supported_inplace_alter(
 
 	  Don't do online ALTER if mtype/unsigned_flag are wrong.
 	*/
-	for (ulint i = 0; i < table->s->fields; i++) {
+	for (ulint i = 0, icol= 0; i < table->s->fields; i++) {
 		const Field*		field = table->field[i];
-		const dict_col_t*	col = dict_table_get_nth_col(prebuilt->table, i);
+		const dict_col_t*	col = dict_table_get_nth_col(prebuilt->table, icol);
 		ulint		unsigned_flag;
+		if (!field->stored_in_db)
+			continue;
+		icol++;
+
 		if (col->mtype != get_innobase_type_from_mysql_type(&unsigned_flag, field)) {
 
 			DBUG_RETURN(HA_ALTER_INPLACE_NOT_SUPPORTED);