MDEV-33655 Remove alter_algorithm

Remove alter_algorithm but keep the variable as no-op (with a warning).

The reasons for removing alter_algorithm are:
- alter_algorithm was introduced as a replacement for the
  old_alter_table that was used to force the usage of the original
  alter table algorithm (copy) in the cases where the new alter
  algorithm did not work. The new option was added as a way to force
  the usage of a specific algorithm when it should instead have made
  it possible to disable algorithms that would not work for some
  reason.
- alter_algorithm introduced some cases where ALTER TABLE would not
  work without specifying the ALGORITHM=XXX option together with
  ALTER TABLE.
- Having different values of alter_algorithm on master and slave could
  cause slave to stop unexpectedly.
- ALTER TABLE FORCE, as used by mariadb-upgrade, would not always work
  if alter_algorithm was set for the server.
- As part of the MDEV-33449 "improving repair of tables" it become
  clear that alter- algorithm made it harder to provide a better and
  more consistent ALTER TABLE FORCE and REPAIR TABLE and it would be
  better to remove it.

Author: montywi

mysql-test/main/alter_table.result

@@ -1654,13 +1654,11 @@ ALTER TABLE m1 ENABLE KEYS, ALGORITHM= INPLACE;
 affected rows: 0
 ALTER TABLE t1 DROP INDEX i1, DROP INDEX i2, DROP INDEX i3, DROP INDEX i4;
 #
-# 2: Test ALGORITHM + alter_algorithm
+# 2: Test ALGORITHM keywords
 #
-SET SESSION alter_algorithm= 1;
-affected rows: 0
 ALTER TABLE t1 ADD INDEX i1(b);
-affected rows: 2
-info: Records: 2  Duplicates: 0  Warnings: 0
+affected rows: 0
+info: Records: 0  Duplicates: 0  Warnings: 0
 ALTER TABLE t1 ADD INDEX i2(b), ALGORITHM= DEFAULT;
 affected rows: 0
 info: Records: 0  Duplicates: 0  Warnings: 1
@@ -1676,8 +1674,6 @@ affected rows: 0
 info: Records: 0  Duplicates: 0  Warnings: 1
 Warnings:
 Note	1831	Duplicate index `i4`. This is deprecated and will be disallowed in a future release
-SET SESSION alter_algorithm= 0;
-affected rows: 0
 ALTER TABLE t1 DROP INDEX i1, DROP INDEX i2, DROP INDEX i3, DROP INDEX i4;
 #
 # 3: Test unsupported in-place operation
@@ -3123,3 +3119,13 @@ DROP TABLE t;
 #
 # End of 10.7 tests
 #
+#
+# MDEV-33655 Remove alter_algorithm
+#
+CREATE TABLE t1 (a INT) ENGINE=MyISAM;
+CREATE TABLE t2 (a INT) ENGINE=MERGE, UNION(t1);
+ALTER TABLE t2 COMMENT 'x', LOCK=SHARED;
+DROP TABLE t2,t1;
+#
+# End of 11.5 tests
+#

mysql-test/main/alter_table.test

@@ -1462,16 +1462,14 @@ ALTER TABLE m1 ENABLE KEYS, ALGORITHM= INPLACE;
 ALTER TABLE t1 DROP INDEX i1, DROP INDEX i2, DROP INDEX i3, DROP INDEX i4;
 
 --echo #
---echo # 2: Test ALGORITHM + alter_algorithm
+--echo # 2: Test ALGORITHM keywords
 --echo #
 
 --enable_info
-SET SESSION alter_algorithm= 1;
 ALTER TABLE t1 ADD INDEX i1(b);
 ALTER TABLE t1 ADD INDEX i2(b), ALGORITHM= DEFAULT;
 ALTER TABLE t1 ADD INDEX i3(b), ALGORITHM= COPY;
 ALTER TABLE t1 ADD INDEX i4(b), ALGORITHM= INPLACE;
-SET SESSION alter_algorithm= 0;
 --disable_info
 
 ALTER TABLE t1 DROP INDEX i1, DROP INDEX i2, DROP INDEX i3, DROP INDEX i4;
@@ -2428,3 +2426,16 @@ DROP TABLE t;
 --echo #
 --echo # End of 10.7 tests
 --echo #
+
+--echo #
+--echo # MDEV-33655 Remove alter_algorithm
+--echo #
+
+CREATE TABLE t1 (a INT) ENGINE=MyISAM;
+CREATE TABLE t2 (a INT) ENGINE=MERGE, UNION(t1);
+ALTER TABLE t2 COMMENT 'x', LOCK=SHARED;
+DROP TABLE t2,t1;
+
+--echo #
+--echo # End of 11.5 tests
+--echo #

mysql-test/main/ignored_index_innodb.result

@@ -1,7 +1,19 @@
 create table t1 (a int, b int, key a1(a)) engine=innodb;
 insert into t1 values (1,1),(2,2),(3,3);
-set alter_algorithm='instant';
-alter table t1 alter index a1 ignored;
-alter table t1 alter index a1 not ignored;
-set alter_algorithm=default;
+alter table t1 alter index a1 ignored, algorithm=instant;
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `a` int(11) DEFAULT NULL,
+  `b` int(11) DEFAULT NULL,
+  KEY `a1` (`a`) IGNORED
+) ENGINE=InnoDB DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
+alter table t1 alter index a1 not ignored, algorithm=instant;
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `a` int(11) DEFAULT NULL,
+  `b` int(11) DEFAULT NULL,
+  KEY `a1` (`a`)
+) ENGINE=InnoDB DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
 drop table t1;

mysql-test/main/ignored_index_innodb.test

@@ -6,11 +6,9 @@
 create table t1 (a int, b int, key a1(a)) engine=innodb;
 insert into t1 values (1,1),(2,2),(3,3);
 
-set alter_algorithm='instant';
-alter table t1 alter index a1 ignored;
+alter table t1 alter index a1 ignored, algorithm=instant;
+show create table t1;
+alter table t1 alter index a1 not ignored, algorithm=instant;
+show create table t1;
 
-alter table t1 alter index a1 not ignored;
-
-set alter_algorithm=default;
 drop table t1;
-

mysql-test/main/innodb_mysql_sync.result

@@ -449,63 +449,14 @@ info: Records: 0  Duplicates: 0  Warnings: 0
 ALTER TABLE t1 ENGINE=INNODB;
 affected rows: 0
 info: Records: 0  Duplicates: 0  Warnings: 0
-#ALTER TABLE FORCE, ALTER TABLE ENGINE and OPTIMIZE TABLE uses
-#table copy when the alter_algorithm enabled.
-SET SESSION alter_algorithm= TRUE;
-affected rows: 0
-ALTER TABLE t1 FORCE;
+# ALTER TABLE FORCE and ALTER TABLE ENGINE uses table copy
+# when ALGORITHM COPY is used.
+ALTER TABLE t1 FORCE, ALGORITHM= COPY;
 affected rows: 1
 info: Records: 1  Duplicates: 0  Warnings: 0
-ALTER TABLE t1 ENGINE= INNODB;
+ALTER TABLE t1 ENGINE= INNODB, ALGORITHM= COPY;
 affected rows: 1
 info: Records: 1  Duplicates: 0  Warnings: 0
-SET DEBUG_SYNC= 'alter_table_copy_after_lock_upgrade SIGNAL upgraded';
-affected rows: 0
-#OPTIMIZE TABLE operation using table copy.
-OPTIMIZE TABLE t1;
-connection con1;
-SET DEBUG_SYNC= 'now WAIT_FOR upgraded';
-affected rows: 0
-INSERT INTO t1 VALUES(10, 20);
-affected rows: 1
-connection default;
-Table	Op	Msg_type	Msg_text
-test.t1	optimize	note	Table does not support optimize, doing recreate + analyze instead
-test.t1	optimize	status	OK
-affected rows: 2
-SET DEBUG_SYNC= 'RESET';
-affected rows: 0
-SET SESSION alter_algorithm= FALSE;
-affected rows: 0
-#ALTER TABLE FORCE and ALTER TABLE ENGINE uses table copy
-#when ALGORITHM COPY is used.
-ALTER TABLE t1 FORCE, ALGORITHM= COPY;
-affected rows: 2
-info: Records: 2  Duplicates: 0  Warnings: 0
-ALTER TABLE t1 ENGINE= INNODB, ALGORITHM= COPY;
-affected rows: 2
-info: Records: 2  Duplicates: 0  Warnings: 0
-DROP TABLE t1;
-#OPTIMIZE TABLE on a table with FULLTEXT index uses
-#ALTER TABLE FORCE using COPY algorithm here. This
-#test case ensures the COPY table debug sync point is hit.
-SET DEBUG_SYNC= 'alter_table_copy_after_lock_upgrade SIGNAL upgraded';
-#Setup a table with FULLTEXT index.
-connection default;
-CREATE TABLE t1(fld1 CHAR(10), FULLTEXT(fld1), FULLTEXT(fld1)) ENGINE= INNODB;
-Warnings:
-Note	1831	Duplicate index `fld1_2`. This is deprecated and will be disallowed in a future release
-INSERT INTO t1 VALUES("String1");
-#OPTIMIZE TABLE operation.
-OPTIMIZE TABLE t1;
-connection con1;
-SET DEBUG_SYNC= 'now WAIT_FOR upgraded';
-INSERT INTO t1 VALUES("String2");
-connection default;
-Table	Op	Msg_type	Msg_text
-test.t1	optimize	note	Table does not support optimize, doing recreate + analyze instead
-test.t1	optimize	status	OK
-SET DEBUG_SYNC= 'RESET';
 DROP TABLE t1;
 #Test which demonstrates that ALTER TABLE, OPTIMIZE PARTITION
 #takes OPTIMIZE TABLE code path, hence does an online rebuild

mysql-test/main/innodb_mysql_sync.test

@@ -611,57 +611,15 @@ INSERT INTO t1 VALUES(10, 20);
 ALTER TABLE t1 FORCE;
 ALTER TABLE t1 ENGINE=INNODB;
 
---echo #ALTER TABLE FORCE, ALTER TABLE ENGINE and OPTIMIZE TABLE uses
---echo #table copy when the alter_algorithm enabled.
-SET SESSION alter_algorithm= TRUE;
-ALTER TABLE t1 FORCE;
-ALTER TABLE t1 ENGINE= INNODB;
-
-SET DEBUG_SYNC= 'alter_table_copy_after_lock_upgrade SIGNAL upgraded';
---echo #OPTIMIZE TABLE operation using table copy.
---send OPTIMIZE TABLE t1
-
---connection con1
-SET DEBUG_SYNC= 'now WAIT_FOR upgraded';
-INSERT INTO t1 VALUES(10, 20);
-
---connection default
---reap
-SET DEBUG_SYNC= 'RESET';
-SET SESSION alter_algorithm= FALSE;
-
---echo #ALTER TABLE FORCE and ALTER TABLE ENGINE uses table copy
---echo #when ALGORITHM COPY is used.
+--echo # ALTER TABLE FORCE and ALTER TABLE ENGINE uses table copy
+--echo # when ALGORITHM COPY is used.
 ALTER TABLE t1 FORCE, ALGORITHM= COPY;
 ALTER TABLE t1 ENGINE= INNODB, ALGORITHM= COPY;
 --disable_info
 
 #cleanup
 DROP TABLE t1;
 
---echo #OPTIMIZE TABLE on a table with FULLTEXT index uses
---echo #ALTER TABLE FORCE using COPY algorithm here. This
---echo #test case ensures the COPY table debug sync point is hit.
-
-SET DEBUG_SYNC= 'alter_table_copy_after_lock_upgrade SIGNAL upgraded';
-
---echo #Setup a table with FULLTEXT index.
---connection default
-CREATE TABLE t1(fld1 CHAR(10), FULLTEXT(fld1), FULLTEXT(fld1)) ENGINE= INNODB;
-INSERT INTO t1 VALUES("String1");
-
---echo #OPTIMIZE TABLE operation.
---send OPTIMIZE TABLE t1
-
---connection con1
-SET DEBUG_SYNC= 'now WAIT_FOR upgraded';
-INSERT INTO t1 VALUES("String2");
-
---connection default
---reap
-SET DEBUG_SYNC= 'RESET';
-DROP TABLE t1;
-
 --echo #Test which demonstrates that ALTER TABLE, OPTIMIZE PARTITION
 --echo #takes OPTIMIZE TABLE code path, hence does an online rebuild
 --echo #of the table with the patch. 

mysql-test/main/load_timezones_with_alter_algorithm_inplace.result

@@ -104,6 +104,10 @@ execute immediate if(@wsrep_cannot_replicate_tz, concat('ALTER TABLE time_zone_n
 execute immediate if(@wsrep_cannot_replicate_tz, concat('ALTER TABLE time_zone_transition ENGINE=', @time_zone_transition_engine, ', ORDER BY Time_zone_id, Transition_time'), 'do 0');
 execute immediate if(@wsrep_cannot_replicate_tz, concat('ALTER TABLE time_zone_transition_type ENGINE=', @time_zone_transition_type_engine, ', ORDER BY Time_zone_id, Transition_type_id'), 'do 0');
 SET session alter_algorithm=@old_alter_alg;
+Warnings:
+Warning	4200	The variable '@@alter_algorithm' is deleted and ignored. It it only exists for compatiblity with old installations
+Warnings:
+Warning	4200	The variable '@@alter_algorithm' is deleted and ignored. It it only exists for compatiblity with old installations
 SELECT COUNT(*) FROM time_zone;
 COUNT(*)
 2
@@ -161,6 +165,10 @@ execute immediate if(@wsrep_cannot_replicate_tz, 'do 0','ALTER TABLE time_zone_t
 SET SESSION SQL_LOG_BIN=@save_sql_log_bin;
 execute immediate if(@wsrep_is_on, 'SET SESSION WSREP_ON=@save_wsrep_on', 'do 0');
 SET session alter_algorithm=@old_alter_alg;
+Warnings:
+Warning	4200	The variable '@@alter_algorithm' is deleted and ignored. It it only exists for compatiblity with old installations
+Warnings:
+Warning	4200	The variable '@@alter_algorithm' is deleted and ignored. It it only exists for compatiblity with old installations
 SELECT COUNT(*) FROM time_zone;
 COUNT(*)
 2
@@ -481,6 +489,10 @@ execute immediate if(@wsrep_is_on, 'SET SESSION WSREP_ON=@save_wsrep_on', 'do 0'
 # MDEV-29347 MariaDB 10.6.8 fails to start when ONLY_FULL_GROUP_BY gets provided
 #
 set sql_mode=only_full_group_by;
+Warnings:
+Warning	4200	The variable '@@alter_algorithm' is deleted and ignored. It it only exists for compatiblity with old installations
+Warnings:
+Warning	4200	The variable '@@alter_algorithm' is deleted and ignored. It it only exists for compatiblity with old installations
 SELECT COUNT(*) FROM time_zone;
 COUNT(*)
 2