Extra writes to slave_worker_info table with duplicate GTIDs

Bug #1712911 reported by Sveta Smirnova on 2017-08-24
8
This bug affects 1 person
Affects Status Importance Assigned to Milestone
Percona Server moved to https://jira.percona.com/projects/PS
Status tracked in 5.7
5.5
Invalid
Undecided
Unassigned
5.6
Invalid
Undecided
Unassigned
5.7
Triaged
Medium
Unassigned

Bug Description

After fix of bug #1669928 if one uses slave-parallel-workers > 1 table slave_worker_info gets updated each time it receives GTID no matter if same GTID was already applied or not.

How to repeat:

1. Start 1 mysqld server (master)
2. Create 1 or more slaves of 1
3. Create one more slave of 1 and of 2 using multiple channels
4. Run write load on 1
5. Compare number of writes to table slave_worker_info on 2 and 3

Suggested fix:

Update slave_worker_info only once for each of unique GTIDs

Sveta Smirnova (svetasmirnova) wrote :

Upstream bug is still https://bugs.mysql.com/bug.php?id=85141, linked with bug #1669928, because it is still not fixed.

Sveta Smirnova (svetasmirnova) wrote :
Sveta Smirnova (svetasmirnova) wrote :
tags: added: performance
Sveta Smirnova (svetasmirnova) wrote :
Sveta Smirnova (svetasmirnova) wrote :

Workaround: convert slave_worker_info to MyISAM storage engine. You will loose ability to monitor status of workers however.

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PS-1819

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