Percona Monthly Bug Report: July 2020

Percona Monthly Bug Report

Percona Monthly Bug ReportAt Percona, we operate on the premise that full-transparency makes a product better. We strive to build not only the best open-source database products but also to help you manage any issues that arise in any of the databases that we support. And, in true open-source form, report back on any issues or bugs you might encounter along the way.

We constantly update our bug reports and monitor other boards to ensure we have the latest information, but we wanted to make it a little easier for you to keep track of the most critical ones. This monthly post is a central place to get information on the most noteworthy open and recently resolved bugs.

In the July 2020 edition of our monthly bug report, we have the following list of bugs:

Percona Server for MySQL/MySQL Bugs


PS-7163(MySQL#99286):Concurrent update cause crash in row_search_mvcc

Affects Version/s: 5.7  [Tested/Reported version 5.7.29]

Concurrent update on a record (a combination of DELETE/INSERT and UPDATE ) could lead to this crash. This bug is critical since such operations are common for many database environments.


PS-6800(MySQL#98142): Uncontrollable memory allocation with TRIGGERS, PROCEDURES, and FUNCTIONS

Affects Version/s: 5.7,8.0  [Tested/Reported version 5.7.29, 8.0.19]

This is a critical bug because it will result in “Out Of Memory” for users who use routines extensively.


PS-7019(MySQL#99398): Correct query results for LEFT JOIN with GROUP BY

Affects Version/s: 8.0 [Tested/Reported version Upstream mysql# 8.0.20]

Fixed Version: PS-8.0.20 and MySQL-8.0.21

This bug is critical since it resulting in incorrect data.


PS-5641(MySQL#95863): Multithreaded slave replication deadlock when set super_read_only to ON

 Affects Version/s: 5.7,8.0  [Tested/Reported version 5.7.26, 8.0.15]


Percona XtraDB Cluster


PXC-3248: PXC 8 crashes on startup when upgrading from 5.7

Affects Version/s: 8.0   [ Tested/Reported 8.0.18]

Source of this bug is PS-7057, where upgrade failed with a crash when innodb_track_changed_pages


PXC-3352: Unexpected ERROR 1205 modifying a child table in a FK relationship

Affects Version/s: 5.7   [Tested/Reported 5.7.28]

Affected users using foreign keys with PXC, When deleting/updating from a child table in a FK relationship, if a parent table has referenced row(s) locked, the operation on a child table will get locked and fail as soon as the parent table is unlocked. For UPDATE case, it’s important to touch a column, which is a part of a constraint.


Percona XtraBackup


PXB-2237: PXB crashes during backup when an encrypted table is updated

Affects Version/s:  2.4  [Tested/Reported version 2.4.20]

Databases with encrypted tables are affected by this bug. As a workaround, Taking backup in non-peak hours could avoid this crash.


PXB-2178: Restoring datadir from partial backup results in an inconsistent data dictionary

Affects Version/s:  8.0  [Tested/Reported version 8.0.11

Issue evident only in XtraBackup 8.0 due to new data dictionary implementation in MySQL 8.0 version, this issue is not reproducible with XtraBackup 2.4.


Percona Toolkit


PT-1859: pt-pg-summary fails for Postgres12

Affects Version/s:  3.2  [Tested/Reported version 3.2.0]

Fixed Version: 3.2.1


PT-1853: pt-online-schema-change doesn’t handle self-referencing foreign keys properly

Affects Version/s:  3.x  [Tested/Reported version 3.2.0]

Affects who rebuild tables with a self-referencing foreign key.


Percona Monitoring and Management (PMM)


PMM-6153: PMM 2.7.0 inoperable when no Internet connectivity

Affects Version/s:  2.7  [Tested/Reported version 2.7.0]

Fixed Version: 2.8

This bug is critical since, If there is no external internet access on pmm-server docker container, then the Nginx process will keep restarting and pmm-client cannot communicate to pmm-server.


PMM-5823: pmm-server log download and api to get the version failed with timeout

Affects Version/s:  2.8  [Tested/Reported version 2.2]

Occurring at irregular intervals and only affected to pmm docker installation with no external internet access from pmm-server docker container. Critical for automated deployment of the PMM server because it will interrupt pmm-client and server communication for while after pmm server installation



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Quick References:

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About Percona:

As the only provider of distributions for all three of the most popular open source databases—PostgreSQL, MySQL, and MongoDB—Percona provides expertise, software, support, and services no matter the technology.

Whether its enabling developers or DBAs to realize value faster with tools, advice, and guidance, or making sure applications can scale and handle peak loads, Percona is here to help.

Percona is committed to being open source and preventing vendor lock-in. Percona contributes all changes to the upstream community for possible inclusion in future product releases.

by Lalit Choudhary via Percona Database Performance Blog