major/MySQLTuner-perl

Recommendation on table_open_cache_instances

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#480 opened on Feb 4, 2020

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 (1 comment) (2 reactions) (1 assignee)Perl (9,452 stars) (1,293 forks)batch import
Help Wantedenhancement

Description

table_open_cache could be a source of contention as default value is 1 in mysql version prior to 7.

The recommended value is 0.5 per CPU to split work load across CPU and reduce locking issue on the table cache partition. Using a big value doesn't reduce performance. Mysql 7 have a default value at 16.

Contributor guide

Tech stack
mysql
Domain
databaseperformance
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
Perl programming basicsMySQL performance tuning concepts
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
Review the MySQLTuner.pl script to find where current cached table checks are made (e.g., table open cache recommendation). Implement a new check for table open cache instances using the pattern: recommend setting to N per CPU. Handle both MySQL 5.x (default 1) and 7.x (default 16). Test script against MySQL instances with different CPU counts.