don't do DROP SYSTEM VERSIONING online

because ALTER TABLE ... DROP SYSTEM VERSIONING
is not just a change in the table structure, it also deletes
all historical rows

mysql-test/main/alter_table_online.result

@@ -408,55 +408,8 @@ a	b	UNIX_TIMESTAMP(row_start)	UNIX_TIMESTAMP(row_end)
 1	55	1.000000	2147483647.999999
 3	44	1.000000	2147483647.999999
 6	77	1.000000	2147483647.999999
-connection con2;
-set debug_sync= 'now WAIT_FOR ended';
-connection default;
-set debug_sync= 'alter_table_copy_end SIGNAL ended WAIT_FOR end';
-alter table t1 drop system versioning,
-algorithm= copy, lock= none;
-connection con2;
-update t1 set b= 88 where a = 1;
-set debug_sync= 'now SIGNAL end';
-connection default;
-# Can't UPDATE versioned -> plain (and can't DELETE)
-ERROR 23000: Duplicate entry '1' for key 'PRIMARY'
-show create table t1;
-Table	Create Table
-t1	CREATE TABLE `t1` (
-  `a` int(11) NOT NULL,
-  `b` int(11) DEFAULT NULL,
-  PRIMARY KEY (`a`)
-) ENGINE=InnoDB DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci WITH SYSTEM VERSIONING
-select *, UNIX_TIMESTAMP(row_start), UNIX_TIMESTAMP(row_end) from t1 for system_time all;
-a	b	UNIX_TIMESTAMP(row_start)	UNIX_TIMESTAMP(row_end)
-1	55	1.000000	3.000000
-1	88	3.000000	2147483647.999999
-3	44	1.000000	2147483647.999999
-6	77	1.000000	2147483647.999999
-connection con2;
-set debug_sync= 'now WAIT_FOR ended';
-connection default;
-set debug_sync= 'alter_table_copy_end SIGNAL ended WAIT_FOR end';
-alter table t1 drop system versioning,
-algorithm= copy, lock= none;
-connection con2;
-insert into t1 values (8, 99);
-set debug_sync= 'now SIGNAL end';
-connection default;
-# INSERT versioned -> plain works fine since it is a single versioned op.
-show create table t1;
-Table	Create Table
-t1	CREATE TABLE `t1` (
-  `a` int(11) NOT NULL,
-  `b` int(11) DEFAULT NULL,
-  PRIMARY KEY (`a`)
-) ENGINE=InnoDB DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
-select * from t1;
-a	b
-1	88
-3	44
-6	77
-8	99
+alter table t1 drop system versioning, algorithm= copy, lock= none;
+ERROR 0A000: LOCK=NONE is not supported. Reason: COPY algorithm requires a lock. Try LOCK=SHARED
 #
 # Test ROLLBACK TO SAVEPOINT
 #

mysql-test/main/alter_table_online.test

@@ -492,52 +492,53 @@ set debug_sync= 'now SIGNAL end';
 show create table t1;
 select *, UNIX_TIMESTAMP(row_start), UNIX_TIMESTAMP(row_end) from t1 for system_time all;
 
---connection con2
---send
-set debug_sync= 'now WAIT_FOR ended';
-
---connection default
-set debug_sync= 'alter_table_copy_end SIGNAL ended WAIT_FOR end';
-
---send
-alter table t1 drop system versioning,
-            algorithm= copy, lock= none;
-
---connection con2
---reap
-update t1 set b= 88 where a = 1;
-
-set debug_sync= 'now SIGNAL end';
-
---connection default
---echo # Can't UPDATE versioned -> plain (and can't DELETE)
---error ER_DUP_ENTRY
---reap
-show create table t1;
-select *, UNIX_TIMESTAMP(row_start), UNIX_TIMESTAMP(row_end) from t1 for system_time all;
-
---connection con2
---send
-set debug_sync= 'now WAIT_FOR ended';
-
---connection default
-set debug_sync= 'alter_table_copy_end SIGNAL ended WAIT_FOR end';
-
---send
-alter table t1 drop system versioning,
-            algorithm= copy, lock= none;
-
---connection con2
---reap
-insert into t1 values (8, 99);
-
-set debug_sync= 'now SIGNAL end';
-
---connection default
---echo # INSERT versioned -> plain works fine since it is a single versioned op.
---reap
-show create table t1;
-select * from t1;
+## at the moment DROP SYSTEM VERSIONING cannot be done online
+## because it not only alters the structure, but also deletes history rows
+--error ER_ALTER_OPERATION_NOT_SUPPORTED_REASON
+alter table t1 drop system versioning, algorithm= copy, lock= none;
+#--connection con2
+#--send
+#set debug_sync= 'now WAIT_FOR ended';
+#
+#--connection default
+#set debug_sync= 'alter_table_copy_end SIGNAL ended WAIT_FOR end';
+#
+#--send
+#alter table t1 drop system versioning,
+#            algorithm= copy, lock= none;
+#
+#--connection con2
+#--reap
+#update t1 set b= 88 where a = 1;
+#
+#set debug_sync= 'now SIGNAL end';
+#
+#--connection default
+#--reap
+#show create table t1;
+#select *, UNIX_TIMESTAMP(row_start), UNIX_TIMESTAMP(row_end) from t1 for system_time all;
+#
+#--connection con2
+#--send
+#set debug_sync= 'now WAIT_FOR ended';
+#
+#--connection default
+#set debug_sync= 'alter_table_copy_end SIGNAL ended WAIT_FOR end';
+#
+#--send
+#alter table t1 drop system versioning,
+#            algorithm= copy, lock= none;
+#
+#--connection con2
+#--reap
+#insert into t1 values (8, 99);
+#
+#set debug_sync= 'now SIGNAL end';
+#
+#--connection default
+#--reap
+#show create table t1;
+#select * from t1;
 
 --echo #
 --echo # Test ROLLBACK TO SAVEPOINT

sql/sql_table.cc

@@ -10028,6 +10028,7 @@ bool mysql_alter_table(THD *thd, const LEX_CSTRING *new_db,
 
   if (alter_info->requested_lock == Alter_info::ALTER_TABLE_LOCK_SHARED
       || alter_info->requested_lock > Alter_info::ALTER_TABLE_LOCK_NONE
+      || alter_info->flags & ALTER_DROP_SYSTEM_VERSIONING
       || thd->locked_tables_mode == LTM_LOCK_TABLES
       || thd->lex->sql_command == SQLCOM_OPTIMIZE
       || alter_info->algorithm(thd) > Alter_info::ALTER_TABLE_ALGORITHM_COPY)