[MDEV-18648] slave_parallel_mode= optimistic default in 10.5 Created: 2019-02-19  Updated: 2020-05-05  Resolved: 2019-12-23

Status: Closed
Project: MariaDB Server
Component/s: Replication
Fix Version/s: 10.5.1

Type: Task Priority: Critical
Reporter: Andrei Elkin Assignee: Alice Sherepa
Resolution: Fixed Votes: 0
Labels: None

Issue Links:
Duplicate
is duplicated by MDEV-10244 Change default to use optimistic mode... Closed
Relates
relates to MDEV-20605 Awaken transaction can miss inserted ... Closed

 Description   

To change CONSERVATIVE @@global.slave_parallel_mode default to OPTIMISTIC in 10.5.



 Comments   
Comment by Geoff Montee (Inactive) [ 2019-09-12 ]

Elkin mentioned to me that optimistic and aggressive mode tend to be more reliable and less likely to hit bugs when binlog_format is set to ROW. This is because these modes rely on internal rollbacks and retries in order to properly work, and these internal rollbacks and retries are more likely to have unexpected side effects when binlog_format is set to STATEMENT or MIXED.

If we change the default value for slave_parallel_mode to optimistic in 10.5, then should we also change the default value of binlog_format to ROW?

Comment by Andrei Elkin [ 2019-09-13 ]

GeoffMontee: that's a good point, and did not weigh my MIXED preference against the "looming" OPTIMISTIC.
Let us discuss your proposal with architecture, QA and replication teams.

Comment by Sujatha Sivakumar (Inactive) [ 2019-09-18 ]

Hello Andrei,

Can you please review the MDEV-18648 changes.

https://github.com/MariaDB/server/commit/cde9170709cec4d64ecf8c4c162be851223206fd

http://buildbot.askmonty.org/buildbot/grid?category=main&branch=bb-10.5-sujatha

Thank you

Comment by Andrei Elkin [ 2019-10-11 ]

GeoffMontee: just for the records, bugs like MDEV-20605 were meant. ROW format load is free from it.

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