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Displaying posts with tag: performance schema (reset)

Part 1: How to Effectively Use a Performance Schema
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Performance Schema (PS) has been the subject of many, many recent discussions, presentations, and articles.  After its release in MySQL 5.7, PS has become the main actor for people who want to take the further steps in MySQL monitoring. At the same time, it has become clear that Oracle intends to make PS powerful with so many features and new instrumentation that old-style monitoring will begin to look like obsolete tools from the Stone Age.

This article will explain PS and provide guidance on what needs to be done in order to use it effectively.

What I am not going to do is to dig into specific performance issues or address polemics about what PS …

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Performance Schema: Great Power Comes Without Great Cost
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Performance Schema is used extensively both internally and within the MySQL community, and I expect even more usage with the new SYS Schema and the Performance Schema enhancements in 5.7. Performance Schema is the single best tool available for monitoring MySQL Server internals and execution details at a lower level. Having said that, we are …

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Profiling MySQL queries from Performance Schema
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When optimizing queries and investigating performance issues, MySQL comes with built in support for profiling queries aka

SET profiling = 1;

 . This is already awesome and simple to use, but why the PERFORMANCE_SCHEMA alternative?

Because profiling will be removed soon (already deprecated on MySQL 5.6 ad 5.7); the built-in profiling capability can only be enabled per session. This means that you cannot capture profiling information for queries running from other connections. If you are using Percona Server, the …

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More on (transactional) MySQL metadata locks
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Two years ago Ovais Tariq had explained in detail what kinds of problems existed before MySQL introduced metadata locks in 5.5.3 and how these locks help to prevent them. Still, some implications of metadata locking in MySQL remain unclear for users – DBAs and even software developers that target recent MySQL versions. I’ve decided to include a slide or two into the …

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MySQL Statement Digests
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Decoupling Statement Digests From Performance Schema

MySQL Statement Digests are a feature originally introduced as part of the MySQL Performance Schema in MySQL 5.6 to aggregate statement statistics based on the normalized statements executed within the server (for additional info, see here).

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MySQL Statement Digests: Configurable Max Lengths
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MySQL Statement Digests are a feature originally introduced as part of the MySQL Performance Schema in MySQL 5.6 to aggregate statement statistics based on the normalized statements executed within the server (for additional info, see here).

Digest calculations are done based on the tokens found in the statement text. The length to …

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MySQL Performance Schema: Instrumentation Exceptions
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The setup_actors table in MySQL Performance Schema can be used to specify what users and hosts one wants to have instrumentation enabled for. By default, connections from all users and hosts are instrumented:

mysql> select * from performance_schema.setup_actors;
+------+------+------+
| HOST | USER | ROLE |
+------+------+------+
| %    | %    | %    |
+------+------+------+
1 row in set (0.00 sec)

You can then use standard SQL against this …


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Easy query metrics with MySQL Performance Schema
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The MySQL Performance Schema exposes so much data that it’s not trivial to learn, configure, and use. With recently released Percona Agent 1.0.11 you can get query metrics – like min, max, and average query execution time – with a few clicks:

Click “Apply” and about two minutes later you’ll have query …

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Sys Schema for MySQL 5.6 and MySQL 5.7
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Performance Schema (P_S) has been available since MySQL 5.5, more than 4 years ago. It is still difficult to see production servers with P_S enabled, even with MySQL 5.6 where the feature is enabled by default. There have been several complaints like the overhead, that the fix is a work in progress, and the ease of use. 52 tables to query and 31 configuration variables is enough to scare people.

There is a solution for the second problem, the usability. It’s name is “sys schema“. It is a collection of views, functions and procedures to make P_S more user friendly.

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Better Performance for JOINs Not Using Indexes
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In some cases it is not possible to use an index to optimize a JOIN. This may for example happen when you query the Performance Schema. As a result these kind of queries can be very slow; however in MySQL 5.6 and later you can use a trick to improve the performance considerably.

As a working example in this post, I will use the schema_table_statistics view in the sys schema. Since the view involves the schema, I will create a reasonable large number of databases …

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Showing entries 1 to 10 of 28 10 Older Entries

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