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Code Activity

MDEV-20122: Deprecate MASTER_USE_GTID=Current_Pos to favor new MASTER_DEMOTE_TO_SLAVE option

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New Feature:
========
This feature adds a safe replacement to the
MASTER_USE_GTID=Current_Pos option for CHANGE MASTER TO as
MASTER_DEMOTE_TO_SLAVE=<bool>. The use case of Current_Pos is to
transition a master to become a slave; however, can break
replication state if the slave executes local transactions due to
actively updating gtid_current_pos with gtid_binlog_pos and
gtid_slave_pos.

MASTER_DEMOTE_TO_SLAVE changes this use case by forcing users to set
Using_Gtid=Slave_Pos and merging gtid_binlog_pos into gtid_slave_pos
once at CHANGE MASTER TO time. Note that if gtid_slave_pos is more
recent than gtid_binlog_pos (as in the case of chain replication),
the replication state should be preserved.

Additionally, deprecate the `Current_Pos` option of MASTER_USE_GTID
to suggest the safe alternative option MASTER_DEMOTE_TO_SLAVE=TRUE.

Reviewed By:
============
Andrei Elkin <andrei.elkin@mariadb.com>
This commit is contained in:
Brandon Nesterenko
2022-06-07 20:06:42 -06:00
parent 5ab5ff08b0
commit 90c3b2835d
39 changed files with 1441 additions and 27 deletions
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89
mysql-test/suite/rpl/include/rpl_change_master_demote.inc Normal file
View File

@@ -0,0 +1,89 @@
#
# This file tests that a master can be demoted to a slave using
# CHANGE MASTER TO MASTER_DEMOTE_TO_SLAVE=1 and replication will work correctly
# afterwards.
#
# param $ignore_domain_ids : List of GTID domain ids to use for
# CHANGE MASTER TO IGNORE_DOMAIN_IDS
#
--let $include_filename= rpl_change_master_demote.inc
--source include/begin_include_file.inc
--echo ##############################################
--echo # Connection semantics change:
--echo # * True primary is now connection 'slave'
--echo # * True replica is now connection 'master'
--echo ##############################################
--connection master
SELECT VARIABLE_NAME, GLOBAL_VALUE FROM INFORMATION_SCHEMA.SYSTEM_VARIABLES WHERE VARIABLE_NAME LIKE 'gtid_binlog_pos' OR VARIABLE_NAME LIKE 'gtid_slave_pos' OR VARIABLE_NAME LIKE 'gtid_current_pos' ORDER BY VARIABLE_NAME ASC;
--let $extra_cm_args=
if (`SELECT strcmp("$ignore_domain_ids","") != 0`)
{
--let $extra_cm_args=, ignore_domain_ids=($ignore_domain_ids)
}
--echo # First ensure gtid_slave_pos after master_demote_to_slave matches
--echo # gtid_current_pos calculation
--let $current_pos= `SELECT @@gtid_current_pos`
--replace_result $SLAVE_MYPORT SLAVE_PORT
--eval CHANGE MASTER TO master_host='127.0.0.1', master_port=$SLAVE_MYPORT, master_user='root', master_use_gtid=slave_pos, master_demote_to_slave=1 $extra_cm_args
SELECT VARIABLE_NAME, GLOBAL_VALUE FROM INFORMATION_SCHEMA.SYSTEM_VARIABLES WHERE VARIABLE_NAME LIKE 'gtid_binlog_pos' OR VARIABLE_NAME LIKE 'gtid_slave_pos' OR VARIABLE_NAME LIKE 'gtid_current_pos' ORDER BY VARIABLE_NAME ASC;
--let $slave_pos= `SELECT @@gtid_slave_pos`
--echo # Validating gtid_slave_pos == gtid_binlog_pos..
if ($slave_pos != $current_pos)
{
SELECT VARIABLE_NAME, GLOBAL_VALUE FROM INFORMATION_SCHEMA.SYSTEM_VARIABLES WHERE VARIABLE_NAME LIKE 'gtid_binlog_pos' OR VARIABLE_NAME LIKE 'gtid_slave_pos' OR VARIABLE_NAME LIKE 'gtid_current_pos' ORDER BY VARIABLE_NAME ASC;
die gtid_slave_pos calculation after master_demote_to_slave=1 differs from gtid_current_pos;
}
--echo # ..success
--source include/start_slave.inc
--connection slave
--source include/stop_slave.inc
--echo # Ensuring replication works correctly after role swap
--connection slave
set session gtid_domain_id= 0;
CREATE TABLE repl_t (a int);
INSERT INTO repl_t VALUES (1);
--source include/save_master_gtid.inc
--connection master
--source include/sync_with_master_gtid.inc
--echo # Validating that replication works..
--let $n_replicated_rows= query_get_value(SELECT COUNT(*) FROM repl_t, COUNT(*), 1)
if ($n_replicated_rows != 1)
{
die "Replication is broken";
}
--echo # ..success
--echo # Cleaning up replication check data
--connection slave
DROP TABLE repl_t;
--source include/save_master_gtid.inc
--connection master
--source include/sync_with_master_gtid.inc
SELECT VARIABLE_NAME, GLOBAL_VALUE FROM INFORMATION_SCHEMA.SYSTEM_VARIABLES WHERE VARIABLE_NAME LIKE 'gtid_binlog_pos' OR VARIABLE_NAME LIKE 'gtid_slave_pos' OR VARIABLE_NAME LIKE 'gtid_current_pos' ORDER BY VARIABLE_NAME ASC;
--echo ##############################################
--echo # Connection semantics change:
--echo # * True primary is back to connection 'master'
--echo # * True replica is back to connection 'slave'
--echo ##############################################
--connection master
--source include/stop_slave.inc
--connection slave
--replace_result $MASTER_MYPORT MASTER_PORT
--eval CHANGE MASTER TO master_host='127.0.0.1', master_port=$MASTER_MYPORT, master_user='root', master_use_gtid=slave_pos, master_demote_to_slave=1
--source include/start_slave.inc
--let $include_filename= rpl_change_master_demote.inc
--source include/end_include_file.inc