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Displaying posts with tag: Percona Server for MySQL (reset)
MySQL: Disk Space Exhaustion for Implicit Temporary Tables

I was recently faced with a real issue about completely exhausting the disk space on MySQL. This was a serious issue because of the continuous outages of the service, as the customer had to constantly restart the server and wait for the next outage.

What was happening? In this article, I’m going to explain it and propose solutions.

Implicit temporary tables

MySQL needs to create implicit temporary tables for solving some kinds of queries. The queries that require a sorting stage most of the time need to rely on a temporary table. For example, when you use GROUP BY, ORDER BY or DISTINCT.  Such queries are executed in two stages: the first is to gather the data and put them into a temporary table, the second is to execute the sorting on the temporary table.

A temporary table is also needed in case of some UNION statements evaluation, for …

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Percona Server for MySQL Highlights – binlog_space_limit

I think it is often confusing to compare upstream MySQL and Percona Server for MySQL, and some helpful information can be found in the introductory notes. But what does that really mean for an ordinary DBA, especially if none of the known big extra features are important in a particular use case?

In this article, I would like to start a series of short blog posts highlighting small, often less known, but potentially useful features, available in Percona Server for MySQL. Let’s start with a relatively new feature.

Limit the disk space used by binary logs problem

Historically, dealing with binary logs and the disk space used by them was quite challenging. The only thing that let you control this is the …

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Percona Monitoring and Management (PMM) 2 Beta Is Now Available

We are pleased to announce the release of PMM 2 Beta!  PMM (Percona Monitoring and Management) is a free and open-source platform for managing and monitoring MySQL, MongoDB, and PostgreSQL performance.

  • Query Analytics:
    • MySQL and MongoDB – Slow log, PERFORMANCE_SCHEMA, and Profiler data sources
    • Support for large environments – default view all queries from all instances
    • Filtering – display only the results matching filters such as the schema name or the server instance
    • Sorting and more columns – now sort by any column.
    • Modify Columns – Add one or more columns for any field exposed by the data source
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ProxySQL 2.0.4 and proxysql-admin tool Now Available

ProxySQL 2.0.4, released by ProxySQL, is now available for download in the Percona Repository along with Percona’s proxysql-admin tool.

ProxySQL is a high-performance proxy, currently for MySQL and database servers in the MySQL ecosystem (like Percona Server for MySQL and MariaDB). It acts as an intermediary for client requests seeking resources from the database. René Cannaò created ProxySQL for DBAs as a means of solving complex replication topology issues.

This release includes ProxySQL 2.0.4 which fixes many bugs and introduces a number of features …

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Percona Server for MySQL 5.7.26-29 Is Now Available

Percona announces the release of Percona Server for MySQL 5.7.26-29 on May 27, 2019 (downloads are available here and from the Percona Software Repositories). This release merges changes of MySQL 5.7.26, including all the bug fixes in it. Percona Server for MySQL 5.7.26-29 is now the current GA release in the 5.7 series. All of Percona’s software is open-source and free.

New Features:

  • New …
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Solve Query Failures Regarding ONLY_FULL_GROUP_BY SQL Mode

“Hey, what’s going on with my applications? I installed a newer version of MySQL. I have queries that perfectly run with the older version and now I have a lot of errors.”

This is a question some customers have asked me after upgrading MySQL. In this article, we’ll see what one of the most frequent causes of this issue is, and how to solve it.

We are talking about this error:

ERROR 1055 (42000): Expression #2 of SELECT list is not in GROUP BY clause 
and contains nonaggregated column 'test.web_log.user_id' which is not functionally 
dependent on columns in GROUP BY clause; this is incompatible 
with sql_mode=only_full_group_by

Have you ever seen it?

SQL_MODE

As the first thing let me introduce the concept of SQL_MODE.

MySQL can work using different SQL modes that affect the syntax of the queries and validation checks. Based on the configured value of the …

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MySQL InnoDB Sorted Index Builds

It’s not essential to understand how MySQL® and Percona Server for MySQL build indexes. However, if you have an understanding of the processing, it could help when you want to reserve an appropriate amount of space for data inserts. From MySQL 5.7, developers changed the way they built secondary indexes for InnoDB, applying a bottom-up rather than the top-down approach used in earlier releases. In this post, I’ll walk through an example to show how an InnoDB index is built. At the end, I’ll explain how you can use this understanding to set an appropriate value for innodb_fill_factor.

Index building process

To build an index on a table with existing data, there are the following phases in InnoDB

  1. Read phase (read from clustered index and build secondary index entries)
  2. Merge sort phase
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ProxySQL 2.0.3 and updated proxysql-admin tool

ProxySQL 2.0.3, released by ProxySQL, is now available for download in the Percona Repository along with an updated version of Percona’s proxysql-admin tool.

ProxySQL is a high-performance proxy, currently for MySQL,  and database servers in the MySQL ecosystem (like Percona Server for MySQL and MariaDB). It acts as an intermediary for client requests seeking resources from the database. René Cannaò created ProxySQL for DBAs as a means of solving complex replication topology issues.

The ProxySQL 2.0.3 source and binary packages available from the …

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Percona Server for MySQL 8.0.15-6 Is Now Available

Percona announces the release of Percona Server for MySQL 8.0.15-6 on May 7, 2019 (downloads are available here and from the Percona Software Repositories).

This release is based on MySQL 8.0.14 and 8.0.15. It includes all bug fixes in these releases. Percona Server for MySQL 8.0.15-6 is now the current GA release in the 8.0 series. All of Percona’s software is open-source and free.

Percona Server for MySQL 8.0 includes all the features available in MySQL 8.0 Community Edition in addition to enterprise-grade features developed by …

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Percona Monitoring and Management (PMM) 2.0.0-alpha2 Is Now Available

We are pleased to announce the launch of PMM 2.0.0-alpha2, Percona’s second Alpha release of our long-awaited PMM 2 project! In this release, you’ll find support for MongoDB Metrics and Query Analytics – watch for sharp edges as we expect to find a lot of bugs!  We’ve also expanded our existing support of MySQL from our first Alpha to now include MySQL Slow Log as a data source for Query Analytics, which enhances the Query Detail section to include richer query metadata.

  • MongoDB Metrics – You can now launch PMM 2 against MongoDB and gather metrics and query data!
  • MongoDB Query Analytics – Data source from MongoDB Profiler is here!
  • MySQL Query Analytics
    • Queries source – MySQL Slow Log is here!
    • Sorting and more …
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