[MDEV-15163] Massive performance impact after PTI fix 2 Created: 2018-02-01  Updated: 2021-09-16  Resolved: 2021-09-16

Status: Closed
Project: MariaDB Server
Component/s: Data Manipulation - Subquery
Affects Version/s: 10.1.26
Fix Version/s: N/A

Type: Bug Priority: Major
Reporter: Jean-Marc Messina Assignee: Axel Schwenke
Resolution: Won't Fix Votes: 0
Labels: None
Environment:

Debian stretch

Attachments: File test.sql.gz    
Issue Links:
Relates
relates to MDEV-15072 Massive performance impact after PTI fix Closed

 Description   

I had already opened an issue that got closed legitimately : https://jira.mariadb.org/browse/MDEV-15072

I have more elements but it doesn't seem that i can reopen the ticket so i'm posting a new one here.

Is there a way to reopen it ?

In case it's impossible, here are the elements :

Hello

I have just applied the PTI patch on the OS and it is causing a massive difference in the execution time of a specific query.

Disabling and reenabling PTI enables me to reproduce the difference at will :

PTI disabled : 7s
PTI enabled : 87s

The query :

SELECT * FROM `test` as b1 WHERE b1.`dateFin` > '2018-01-24' AND NOT EXISTS (SELECT 1 FROM `test` as b2 WHERE b2.`ip` = b1.`ip` AND b2.`dateFin` > b1.`dateFin`);

Explain doesn't show any difference with and without KPTI fix.

Please find attached the table to reproduce the issue

 Comments   
Comment by Axel Schwenke [ 2021-09-16 ]

This affects an old version of the server (10.1). If this problem persists with an up-to-date version, please open a new ticket.

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