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

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.

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:

percona-toolkit/pt-mysql-summary at 3.x · percona/percona-toolkit · GitHub
This is checking a system counter that says at some point someone executed an explicit LOCK TABLES DML. SHOW GLOBAL STATUS LIKE "Com_Lock%";

percona-toolkit/pt-mysql-summary at 3.x · percona/percona-toolkit · GitHub
This is checking if you have the Percona UDFs installed
Percona Toolkit UDFs - Percona Server for MySQL

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