What are "Explicit LOCK TABLES" and "Fast Hash UDFs"?

MySQL & MariaDB Percona Server for MySQL 5.7
1

Hello,

I am trying to compare the differences between 2 mysql percona instances and noticed 2 differences being reported by pt-mysql-summary:

  • Explicit LOCK TABLES
  • Fast Hash UDFs

What I would like to understand is what configuration determines whether these are enabled or not? Also, are there any resources that I’m missing for better understanding the output from pt-mysql-summary? I did come across: pt-mysql-summary — Percona Toolkit Documentation but that doesn’t really go into detail for each line item.

2

All Percona software is completely open source, so if you want to know why something is doing something, just go look at the source code :slight_smile:

https://github.com/percona/percona-toolkit/blob/3.x/bin/pt-mysql-summary#L2479
This is checking a system counter that says at some point someone executed an explicit LOCK TABLES DML. SHOW GLOBAL STATUS LIKE "Com_Lock%";

https://github.com/percona/percona-toolkit/blob/3.x/bin/pt-mysql-summary#L2005
This is checking if you have the Percona UDFs installed
https://docs.percona.com/percona-server/8.0/management/udf_percona_toolkit.html

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