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Displaying posts with tag: Percona Monitoring and Management (reset)
Q&A on Webinar “Using PMM to Identify and Troubleshoot Problematic MySQL Queries”

Hi and thanks to all who attended my webinar on Tuesday, January 26th titled Using PMM to Identify & Troubleshoot Problematic MySQL Queries!

Like we do after all our webinars, we compile the list of questions that were answered verbally and also those that were posed yet remained unanswered since we ran out of time during the broadcast.  Before we get to the questions, I wanted to make sure to include a link to the RED Method for MySQL Queries by Peter Zaitsev, Percona’s CEO:

Hi Michael, you suggested that table create and update times should be ignored. Surely these values come from information_schema.tables? Does that not reflect what I would see …

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Understanding MySQL Memory Usage with Performance Schema

Understanding how MySQL uses memory is key to tuning it for optimal performance as well as troubleshooting cases of unexpected memory usage, i.e. when you have MySQL Server using a lot more than you would expect based on your configuration settings.

Early in MySQL history, understanding memory usage details was hard and included a lot of guesswork.  Is it possible that some queries running require a large temporary table or allocated a lot of memory for stored user variables?  Are any stored procedures taking an unexpectedly high amount of memory? All could be reasons for excessive MySQL memory usage, but you would not easily see if that is just the case.

All that changed with MySQL 5.7, which added memory instrumentation in Performance Schema, and with MySQL 8.0, this instrumentation is enabled by default, so you can get this data from pretty much any running instance.

If you’re looking for current memory …

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How to Find Query Slowdowns Using Percona Monitoring and Management

Visibility is a blessing, and with databases, visibility is a must. That’s true not only for metrics but for the queries themselves. Having info on all the stats around query execution is priceless, and Percona Monitoring and Management (PMM) offers that in the form of the Query Analytics dashboard (QAN).

But where to start? QAN helps you with that by calculating the query profile. What is the profile? It’s a rank of queries, ordered by Load, so it is easy to spot the heaviest queries hitting your database. The Load is defined as the “Average Active Queries” but can also be defined as a mix of Query Execution Time Plus Query count. In other words, all the time the query was alive and kicking.

The Profile in PMM 2.10.0 looks like this:

The purpose of this profile is to facilitate the task of finding the …

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How Much Memory Does the Process Really Take on Linux?

One of the questions you often will be faced with operating a Linux-based system is managing memory budget. If a program uses more memory than available you may get swapping to happen, oftentimes with a terrible performance impact, or have Out of Memory (OOM) Killer activated, killing process altogether.

Before adjusting memory usage, either by configuration, optimization, or just managing the load, it helps to know how much memory a given program really uses.

If your system runs essentially a single user program (there is always a bunch of system processes) it is easy.  For example, if I run a dedicated MySQL server on a system with 128GB of RAM I can use “used” as a good proxy of what is used and “available” as what can still be used.

root@rocky:/mnt/data2/mysql# free -h …
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MySQL Query Performance Troubleshooting: Resource-Based Approach

When I speak about MySQL performance troubleshooting (or frankly any other database), I tend to speak about four primary resources which typically end up being a bottleneck and limiting system performance: CPU, Memory, Disk, and Network.

It would be great if when seeing what resource is a bottleneck, we could also easily see what queries contribute the most to its usage and optimize or eliminate them. Unfortunately, it is not as easy as it may seem.

First, MySQL does not really provide very good instrumentation in those terms, and it is not easy to get information on how much CPU usage, Disk IO, or Memory a given query caused.  Second, direct attribution is not even possible in a lot of cases. For example, disk writes from flushing data from the InnoDB buffer pool in the …

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Preventing MySQL Error 1040: Too Many Connections

One of the most common errors encountered in the MySQL world at large is the infamous Error 1040:

ERROR 1040 (00000): Too many connections

What this means in practical terms is that a MySQL instance has reached its maximum allowable limit for client connections.  Until connections are closed, no new connection will be accepted by the server.

I’d like to discuss some practical advice for preventing this situation, or if you find yourself in it, how to recover.

Accurately Tune the max_connections Parameter

This setting defines the maximum number of connections that a MySQL instance will accept.  Considerations on “why” you would want to even have a max number of connections are based on resources available to the server and application usage patterns.  Allowing uncontrolled connections can crash a server, which may be considered “worse” than preventing further …

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MySQL 101: How to Find and Tune a Slow SQL Query

One of the most common support tickets we get at Percona is the infamous “database is running slower” ticket.  While this can be caused by a multitude of factors, it is more often than not caused by a bad query.  While everyone always hopes to recover through some quick config tuning, the real fix is to identify and fix the problem query.  Sure, we can generally alleviate some pain by throwing more resources at the server.  But this is almost always a short term bandaid and not the proper fix.

With Percona Monitoring and Management

So how do we find the queries causing problems and fix them?  If you have Percona Monitoring and Management (PMM) installed, the identification process is swift.  With the Query Analytics enabled (QAN) in PMM, you can simply look at the table …

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RED Method for MySQL Performance Analyses

The RED Method (Rate, Errors, Duration) is one of the more popular performance monitoring approaches.  It is often applied to Monitoring Microservices though there is nothing that prevents it from being applied to databases like MySQL.

In Percona Monitoring and Management (PMM) v2 we have all the required information stored in the ClickHouse database, and with the built-in ClickHouse datasource it is a matter of creating a dashboard to visualize the data.

While I was editing the dashboard, I added a few other panels, beyond what RED Method requires, in order to show some of the cool things you can do with Grafana + ClickHouse data source and …

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Running Custom MySQL Queries in Percona Monitoring and Management

Even though Percona Monitoring and Management 2 (PMM) comes with a lot of dashboards and metrics out of the box, sometimes we need to extend the default metrics by running custom MySQL queries.

For example, suppose you want to have information about cached indexes from Innodb tables from innodb_cached_indexes table. That metric is not being captured by any default dashboard, but it is possible to extend PMM and make it capture the result of custom queries.

Getting Started With Custom Queries

Custom queries can be added to mysqld_exporter by adding them to the appropriate config file in /usr/local/percona/pmm2/collectors/custom-queries/mysql. There are three subdirectories inside it: high-resolution, low-resolution, and medium-resolution. PMM allows …

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Percona Projects for Google Summer of Code – 2020

We are proud to announce that Percona was selected as a participating organization for the Google Summer of Code (GSoC) 2020 program, this is our second year as a participating org with the GSoC program.

GSoC is a great program to involve young student developers in open source projects. We participated in the program in 2019 for the first time and we were really happy and satisfied with the results.
Percona Platform Engineering team decided to participate again for the 2020 program and we are glad and really happy to inform you that we were selected and welcome the student to work with our team during the summer of 2020 on their GSoC Project.


We started planning for GSoC around November-December 2019, with the help from our Product Management team, we were able to shortlist a few ideas which we thought were really the right fit for …

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