[MDEV-17484] New defaults for eq_range_index_dive_limit in 10.4 Created: 2018-10-17  Updated: 2019-02-08  Resolved: 2019-02-01

Status: Closed
Project: MariaDB Server
Component/s: Optimizer
Fix Version/s: 10.4.3

Type: Task Priority: Critical
Reporter: Sergei Petrunia Assignee: Varun Gupta (Inactive)
Resolution: Fixed Votes: 0
Labels: None

Issue Links:
Relates
relates to MDEV-17486 eq_range_index_dives_limit option/var... Closed

 Description   

See https://lists.launchpad.net/maria-developers/msg11460.html :

So, MDEV-16934 introduced eq_range_index_dives_limit into 10.2.8 and 10.3.0.

The default was set to 0 (which means no limit) in order to not introduce
optimizer behavior changes into stable versions.

The question is: should 10.4 also have 0 by default or we can set it to some
finite limit? MySQL's default value is 10.

After the decision was: It should be set to 10. This is what this task is about.

Saw MYSQL 8.0 , the default there is 200
https://dev.mysql.com/doc/refman/8.0/en/server-system-variables.html#sysvar_eq_range_index_dive_limit
psergey igor for your information

 Comments   
Comment by Sergei Petrunia [ 2019-01-22 ]

Ok to push the patch

Comment by Varun Gupta (Inactive) [ 2019-02-06 ]

greenman on the optimizer call we came to the conclusion that we will change the value to 200 instead of 10. The reason to change the value was to have something greater than 0 atleast

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