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Move deletion of old GTID rows to slave background thread

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This patch changes how old rows in mysql.gtid_slave_pos* tables are deleted.
Instead of doing it as part of every replicated transaction in
record_gtid(), it is done periodically (every @@gtid_cleanup_batch_size
transaction) in the slave background thread.

This removes the deletion step from the replication process in SQL or worker
threads, which could speed up replication with many small transactions. It
also decreases contention on the global mutex LOCK_slave_state. And it
simplifies the logic, eg. when a replicated transaction fails after having
deleted old rows.

With this patch, the deletion of old GTID rows happens asynchroneously and
slightly non-deterministic. Thus the number of old rows in
mysql.gtid_slave_pos can temporarily exceed @@gtid_cleanup_batch_size. But
all old rows will be deleted eventually after sufficiently many new GTIDs
have been replicated.
This commit is contained in:
Kristian Nielsen
2018-10-14 20:41:49 +02:00
parent 24a45d3bd7
commit 34f11b06e6
21 changed files with 684 additions and 316 deletions
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14
mysql-test/suite/rpl/r/rpl_parallel_optimistic.result
View File

@ -12,6 +12,8 @@ SET GLOBAL slave_parallel_threads=10;
CHANGE MASTER TO master_use_gtid=slave_pos;
SET @old_parallel_mode=@@GLOBAL.slave_parallel_mode;
SET GLOBAL slave_parallel_mode='optimistic';
SET @old_gtid_cleanup_batch_size= @@GLOBAL.gtid_cleanup_batch_size;
SET GLOBAL gtid_cleanup_batch_size= 1000000;
connection server_1;
INSERT INTO t1 VALUES(1,1);
BEGIN;
@ -131,6 +133,11 @@ c
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205
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SELECT IF(COUNT(*) >= 30, "OK", CONCAT("Error: too few old rows found: ", COUNT(*)))
FROM mysql.gtid_slave_pos;
IF(COUNT(*) >= 30, "OK", CONCAT("Error: too few old rows found: ", COUNT(*)))
OK
SET GLOBAL gtid_cleanup_batch_size=1;
*** Test @@skip_parallel_replication. ***
connection server_2;
include/stop_slave.inc
@ -651,9 +658,10 @@ DROP TABLE t1, t2, t3;
include/save_master_gtid.inc
connection server_2;
include/sync_with_master_gtid.inc
Check that no more than the expected last four GTIDs are in mysql.gtid_slave_pos
select count(4) <= 4 from mysql.gtid_slave_pos order by domain_id, sub_id;
count(4) <= 4
SELECT COUNT(*) <= 5*@@GLOBAL.gtid_cleanup_batch_size
FROM mysql.gtid_slave_pos;
COUNT(*) <= 5*@@GLOBAL.gtid_cleanup_batch_size
1
SET GLOBAL gtid_cleanup_batch_size= @old_gtid_cleanup_batch_size;
connection server_1;
include/rpl_end.inc