这是indexloc提供的服务，不要输入任何密码
Skip to content

MDEV-19574 innodb_stats_method is not honored when innodb_stats_persistent=ON #4187

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom
Open
wants to merge 1 commit into
base: 10.6
Choose a base branch
from
Open

MDEV-19574 innodb_stats_method is not honored when innodb_stats_persistent=ON #4187

wants to merge 1 commit into from

Conversation

Thirunarayanan
Copy link
Member

  • The Jira issue number for this PR is: MDEV-19574

Description

Problem:

InnoDB persistent statistics doesn't take innodb_stats_method
variable while calculating n_diff_pfx for the n-prefix index columns.

Solution:

InnoDB consider all nulls as different value when innodb_stats_method is set to NULLS_UNEQUAL and NULLS_IGNORED.

Release Notes

InnoDB consider innodb_stats_method while calculating persistent statistics

How can this PR be tested?

./mtr innodb.innodb_stats_method

Basing the PR against the correct MariaDB version

  • This is a new feature or a refactoring, and the PR is based against the main branch.
  • This is a bug fix, and the PR is based against the earliest maintained branch in which the bug can be reproduced.

PR quality check

  • I checked the CODING_STANDARDS.md file and my PR conforms to this where appropriate.
  • For any trivial modifications to the PR, I am ok with the reviewer making the changes themselves.

@Thirunarayanan
MDEV-19574 innodb_stats_method is not honored when innodb_stats_persi…
f43dcf7 
…stent=ON

Problem:
=======
 InnoDB persistent statistics doesn't take innodb_stats_method
variable while calculating n_diff_pfx for the n-prefix index
columns.

Solution:
=========
InnoDB consider all nulls as different value when innodb_stats_method
is set to NULLS_UNEQUAL and NULLS_IGNORED.
@Thirunarayanan Thirunarayanan requested a review from dr-m July 11, 2025 14:43
@CLAassistant
Copy link

CLA assistant check
Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
You have signed the CLA already but the status is still pending? Let us recheck it.

dr-m
dr-m reviewed Jul 11, 2025
View reviewed changes
Copy link
Contributor

@dr-m dr-m left a comment

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

The commit message mentions that a value is set to one AND another. It should clearly be OR.

I think that the commit message needs to emphasize that the contents of the statistics depends on the value of the parameter when the statistics were last recalculated. We have an informational column in the statistics tables. Could the used value of innodb_stats_method be written there?

storage/innobase/dict/dict0stats.cc
Comment on lines +1576 to +1577
(srv_innodb_stats_method
> SRV_STATS_NULLS_EQUAL),
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Instead of checking the value of the global variable in each iteration, I think that it would be better to evaluate this condition only once and pass it in a bool parameter to the affected functions.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Reviewers

@dr-m dr-m dr-m left review comments

Assignees
No one assigned
Labels
MariaDB Corporation
Milestone
No milestone
Development

Successfully merging this pull request may close these issues.
3 participants
@Thirunarayanan @CLAassistant @dr-m