Why SELECT COUNT(*) FROM TABLE Is Sometimes Very Slow in MySQL or MariaDB

If you have enough experience with MySQL, it is very possible that you stumbled upon an unusually slow SELECT COUNT(*) FROM TABLE; query execution, at least occasionally. Recently, I had a chance to investigate some of these cases closer, and it stunned me what huge differences there can be depending on the circumstance given the very same table. As the problem turned out to be much more complex t

[tmatsuu]

MySQLで SELECT COUNT(*) FROM TABLEが遅い理由は、レコード数やパラメータ設定、マイナーバージョンでの仕様変更など様々。詳しくはSummaryをご確認ください。