Tag - MySQL Query Tuning

Reducing High CPU on MySQL: a Case Study

CPU Usage after query tuning

In this blog post, I want to share a case we worked on a few days ago. I’ll show you how we approached the resolution of a MySQL performance issue and used Percona Monitoring and Management PMM to support troubleshooting. The customer had noticed a linear high CPU usage in one of their MySQL […]

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Finding Table Differences on Nullable Columns Using MySQL Generated Columns

MySQL generated columns

Some time ago, a customer had a performance issue with an internal process. He was comparing, finding, and reporting the rows that were different between two tables. This is simple if you use a LEFT JOIN and an 
IS NULL  comparison over the second table in the WHERE clause, but what if the column could be […]

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Why Optimization derived_merge can Break Your Queries

MySQL optimizer bugs

Lately, I worked on several queries which started returning wrong results after upgrading MySQL Server to version 5.7 The reason for the failure was derived merge optimization which is one of the default
optimizer_switch  options. Issues were solved, though at the price of performance, when we turned it
OFF . But, more importantly, we could […]

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Webinar: How to Analyze and Tune MySQL Queries for Better Performance

database query tuning

Please join Percona’s MySQL Database Administrator, Brad Mickel as he presents How to Analyze and Tune MySQL Queries for Better Performance on Thursday, June 21st, 2018, at 10:00 AM PDT (UTC-7) / 1:00 PM EDT (UTC-4).
Register Now
 
Query performance is essential in making any application successful. In order to finely tune your queries you first […]

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EXPLAIN FORMAT=JSON wrap-up

EXPLAIN FORMAT=JSON

This blog is an EXPLAIN FORMAT=JSON wrap-up for the series of posts I’ve done in the last few months.
In this series, we’ve discussed everything unique to
EXPLAIN FORMAT=JSON. I intentionally skipped a description of members such as
table_name,
access_type  or
select_id, which are not unique.
In this series, I only mentioned in passing members that […]

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