MDEV-25555 Server crashes in tree_record_pos after INPLACE-recreating index on HEAP table

Drop and add same key is considered rename (look ALTER_RENAME_INDEX in
fill_alter_inplace_info()). But in this case order of keys may be
changed, because mysql_prepare_alter_table() yet does not know about
rename and treats 2 operations: drop and add.

In that case we disable inplace algorithm for such engines as Memory,
MyISAM and Aria with ALTER_INDEX_ORDER flag. These engines have no
specialized check_if_supported_inplace_alter() and default
handler::check_if_supported_inplace_alter() sees an unknown flag and
returns HA_ALTER_INPLACE_NOT_SUPPORTED.

ha_innobase::check_if_supported_inplace_alter() works differently and
inplace is not disabled (with the help of modified
INNOBASE_INPLACE_IGNORE). add_drop_v_cols fork was also tweaked as it
wrongly failed with MSG_UNSUPPORTED_ALTER_ONLINE_ON_VIRTUAL_COLUMN
when it seen ALTER_INDEX_ORDER.

No-op operation must be still no-op no matter of ALTER_INDEX_ORDER
presence, so we tweek its condition as well.

mysql-test/main/alter_table.result

@@ -3389,5 +3389,15 @@ test.t1	check	status	OK
 drop table t1;
 set @@default_storage_engine= @save_default_engine;
 #
+# MDEV-25555 Server crashes in tree_record_pos after INPLACE-recreating index on HEAP table
+#
+create table t1 (a int, key idx1(a), key idx2 using btree(a)) engine=memory;
+alter table t1 rename index idx1 to idx3, algorithm=inplace;
+delete from t1 where a = 10;
+alter table t1 drop key idx3, add key idx1(a), algorithm=inplace;
+ERROR 0A000: ALGORITHM=INPLACE is not supported for this operation. Try ALGORITHM=COPY
+delete from t1 where a = 11;
+drop table t1;
+#
 # End of 10.5 tests
 #

mysql-test/main/alter_table.test

@@ -2608,6 +2608,18 @@ check table t1;
 drop table t1;
 set @@default_storage_engine= @save_default_engine;
 
+--echo #
+--echo # MDEV-25555 Server crashes in tree_record_pos after INPLACE-recreating index on HEAP table
+--echo #
+create table t1 (a int, key idx1(a), key idx2 using btree(a)) engine=memory;
+alter table t1 rename index idx1 to idx3, algorithm=inplace;
+delete from t1 where a = 10;
+--error ER_ALTER_OPERATION_NOT_SUPPORTED
+alter table t1 drop key idx3, add key idx1(a), algorithm=inplace;
+delete from t1 where a = 11;
+# cleanup
+drop table t1;
+
 --echo #
 --echo # End of 10.5 tests
 --echo #

mysql-test/main/long_unique.result

@@ -596,17 +596,17 @@ t1	CREATE TABLE `t1` (
   `a` int(11) DEFAULT NULL,
   UNIQUE KEY `db_row_hash_1` (`db_row_hash_1`),
   UNIQUE KEY `db_row_hash_2` (`db_row_hash_2`),
+  UNIQUE KEY `d` (`d`) USING HASH,
   UNIQUE KEY `e` (`e`),
-  UNIQUE KEY `a` (`a`),
-  UNIQUE KEY `d` (`d`) USING HASH
+  UNIQUE KEY `a` (`a`)
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 show keys from t1;
 Table	Non_unique	Key_name	Seq_in_index	Column_name	Collation	Cardinality	Sub_part	Packed	Null	Index_type	Comment	Index_comment
 t1	0	db_row_hash_1	1	db_row_hash_1	A	NULL	NULL	NULL	YES	BTREE		
 t1	0	db_row_hash_2	1	db_row_hash_2	A	NULL	NULL	NULL	YES	BTREE		
+t1	0	d	1	d	A	NULL	NULL	NULL	YES	HASH		
 t1	0	e	1	e	A	NULL	NULL	NULL	YES	BTREE		
 t1	0	a	1	a	A	NULL	NULL	NULL	YES	BTREE		
-t1	0	d	1	d	A	NULL	NULL	NULL	YES	HASH		
 alter table t1 add column clm1 blob unique,add column clm2 blob unique;
 #try changing the name; 
 alter table t1 change column clm1 clm_changed1 blob, change column clm2 clm_changed2 blob;

sql/handler.h

@@ -786,6 +786,13 @@ typedef bool Log_func(THD*, TABLE*, bool, const uchar*, const uchar*);
 */
 #define ALTER_COLUMN_INDEX_LENGTH            (1ULL << 60)
 
+/**
+  Indicate that index order might have been changed. Disables inplace algorithm
+  by default (not for InnoDB).
+*/
+#define ALTER_INDEX_ORDER                    (1ULL << 61)
+
+
 /*
   Flags set in partition_flags when altering partitions
 */

sql/sql_table.cc

@@ -10623,6 +10623,8 @@ do_continue:;
   create_info->options|=HA_CREATE_TMP_ALTER;
   if (!(alter_info->flags & ALTER_ADD_INDEX) && !alter_ctx.modified_primary_key)
     create_info->options|= HA_SKIP_KEY_SORT;
+  else
+    alter_info->flags|= ALTER_INDEX_ORDER;
   create_info->alias= alter_ctx.table_name;
   error= create_table_impl(thd, alter_ctx.db, alter_ctx.table_name,
                            alter_ctx.new_db, alter_ctx.tmp_name,
@@ -10659,7 +10661,7 @@ do_continue:;
     */
 
     if (!(ha_alter_info.handler_flags &
-          ~(ALTER_COLUMN_ORDER | ALTER_RENAME_COLUMN)))
+          ~(ALTER_COLUMN_ORDER | ALTER_RENAME_COLUMN | ALTER_INDEX_ORDER)))
     {
       /*
         No-op ALTER, no need to call handler API functions.
@@ -10674,6 +10676,9 @@ do_continue:;
         Also note that we ignore the LOCK clause here.
 
         TODO don't create partitioning metadata in the first place
+
+        TODO: Now case-change index name is treated as noop which is not quite
+              correct.
       */
       table->file->ha_create_partitioning_metadata(alter_ctx.get_tmp_path(),
                                                    NULL, CHF_DELETE_FLAG);

storage/connect/ha_connect.cc

@@ -7205,7 +7205,8 @@ ha_connect::check_if_supported_inplace_alter(TABLE *altered_table,
     ALTER_ADD_UNIQUE_INDEX |
     ALTER_DROP_UNIQUE_INDEX |
     ALTER_ADD_PK_INDEX |
-    ALTER_DROP_PK_INDEX;
+    ALTER_DROP_PK_INDEX |
+    ALTER_INDEX_ORDER;
 
   alter_table_operations inplace_offline_operations=
     ALTER_COLUMN_TYPE_CHANGE_BY_ENGINE |

storage/innobase/handler/handler0alter.cc

@@ -114,6 +114,7 @@ static const alter_table_operations INNOBASE_INPLACE_IGNORE
 	| ALTER_VIRTUAL_GCOL_EXPR
 	| ALTER_DROP_CHECK_CONSTRAINT
 	| ALTER_RENAME
+	| ALTER_INDEX_ORDER
 	| ALTER_COLUMN_INDEX_LENGTH
 	| ALTER_CHANGE_INDEX_COMMENT;
 
@@ -2454,7 +2455,8 @@ next_column:
 			   | ALTER_ADD_UNIQUE_INDEX
 		*/
 			   | ALTER_ADD_NON_UNIQUE_NON_PRIM_INDEX
-			   | ALTER_DROP_NON_UNIQUE_NON_PRIM_INDEX);
+			   | ALTER_DROP_NON_UNIQUE_NON_PRIM_INDEX
+			   | ALTER_INDEX_ORDER);
 		if (supports_instant) {
 			flags &= ~(ALTER_DROP_STORED_COLUMN
 #if 0 /* MDEV-17468: remove check_v_col_in_order() and fix the code */

storage/rocksdb/ha_rocksdb.cc

@@ -12427,6 +12427,7 @@ my_core::enum_alter_inplace_result ha_rocksdb::check_if_supported_inplace_alter(
         ALTER_ADD_NON_UNIQUE_NON_PRIM_INDEX |
         ALTER_PARTITIONED |
         ALTER_ADD_UNIQUE_INDEX |
+        ALTER_INDEX_ORDER |
         ALTER_CHANGE_CREATE_OPTION)) {
     DBUG_RETURN(my_core::HA_ALTER_INPLACE_NOT_SUPPORTED);
   }