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10 Newer Entries Showing entries 31 to 40 of 76 10 Older Entries

Displaying posts with tag: performance_schema (reset)

Practical P_S: From which hosts are connections being attempted?
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MySQL Server has an aborted_connect status counter which will show you the number of failed attempts to establish a new connection.  The manual describes potential causes as follows:

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Practical P_S: Extending PROCESSLIST
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MySQL 5.6 introduced major advances to monitoring made via PERFORMANCE_SCHEMA, but also made a change in how it binds to the network by default.  In MySQL 5.5, the –bind-address configuration option defaulted to “0.0.0.0″, meaning only IPv4.  This changed to “*” in MySQL 5.6, accepting connections on both IPv6 and IPv4 interfaces.  Somehow (I’ve not looked into it yet), my (unsupported) WindowsXP installation now refuses to bind to IPv4,

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Practical P_S: Finding which accounts fail to properly close connections
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I’ve previously written about several problems which can benefit from additional visibility provided by PERFORMANCE_SCHEMA in MySQL 5.6, and it’s time to add to that list.  A very common problem involves connections which are not properly closed – they simply idle until they reach wait_timeout (or interactive_timeout, depending on the client flags set), and the server terminates the connection.  Who knows what the root cause is – perhaps the client terminated without cleaning up connections, or maybe there was just no load, or maybe the network cable was unplugged.  It’s something application developers

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Troubleshooting High Memory Usage with MySQL on Windows
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I was testing out the latest MySQL 5.6 on Windows (having used the auto-installer) and happened to notice my RAM usage (via Windows Task Manager) was reporting quite a high value, when I had very modest ram/buffer settings (should have been around 40M, but instead it was around 400M).

After double/triple-checking my settings to make sure I didn’t overlook something obvious, I searched the bugs database, and ran across bug #68287:

“High Memory Usage with MySQL 5.6.12 GA in ‘Development Machine’ mode”

Turns out, using the auto-installer set the value of table_definition_cache=1400, when the minimum value is 400. Reducing it to 400, and restarting MySQL immediately lowered the RAM usage, and is the “work-around”

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Spreading the word about the Performance Schema
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In case you missed it, more and more people are now spreading the word about the Performance Schema, which is a very good thing.

#DBHangOps 4/10/13

Mark Leith presents the Performance Schema and ps_helpers.

Random quotes from the recording:
"I am already seeing so many benefits out of this, ..."
"This looks fantastic"
"Very cool"

OurSQL Episode 139: Starting to Perform

Sheeri and Gerry present the Performance Schema.

Ramdom quote from the recording:
"I am looking at this feature [digests], and I think it's amazing"

Webinar: MySQL 5.6 Performance

















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30 configuration options and counting
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While Domas may have rather effictively trolled the discussion with his post on howto configure table/user statistics (which gave me a good chuckle I do have to say), it’s at least incorrect for Percona Server as you have to enable the “userstat” server option :)

That being said, once enabled there are no extra configuration variables to think about. This is a huge advantage over configuring PERFORMANCE_SCHEMA - which has a total of THIRTY configuration options (31 if you include the global enable/disable option).

Some of these thirty odd configuration variables are only going to matter if

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On configuring the Performance Schema
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On configuring the Performance Schema

This article is a user guide about MySQL 5.6 Performance Schema configuration. As with many things, the way to approach problems may vary a lot based on systems, user experiences, or just plain opinions, so the "Your Mileage May Vary" caution applies here.

It is easy to get lost in details, and yet starting with the big picture in mind helps to understand not only how, but also more importantly why, to do things ...

The magic recipe is as follows
  • Define your goals
  • Define what to instrument
  • Define how much detail to collect
  • Provide sizing data
  • Monitor sizing problems

Define your goals
Performance instrumentation in general can be used for many different things, ranging from casual monitoring in production to debugging in








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A Visual Guide to the MySQL Performance Schema
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If you haven’t explored the MySQL Performance Schema yet, this is a good place to start.  This is Performance Schema 101, a basic introduction to the MySQL 5.6 performance_schema, which records runtime statistics from the MySQL database. The performance_schema is intended to provide access to useful information about server execution while having minimal impact on server performance.  Performance_schema is the name of both the storage engine and the database itself, and it was initially implemented  in MySQL 5.5. In MySQL 5.6 the engineers added quite a bit of new instrumentation.

The performance_schema database uses views or temporary tables that actually use little to no persistent disk storage .Memory allocation is all done at server startup, so there is no ongoing memory reallocation or

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MyISAM in a MySQL 5.6 InnoDB Only instance
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With MySQL 5.5 the default storage engine was changed to InnoDB. This was a good step as most users expected MySQL to support transactions, row level locking and all the other InnoDB features, but with 5.1 they sometimes forgot to choose the right storage engine. As most databases don't have multiple storage engines and many MySQL users changed the default storage engine to InnoDB this made the switch to MySQL easier and the default behaviour more in line with what people expect from a relational database.

Changing the storage engine can of course be done on a per table or per instance basis (default-storage-engine in my.cnf). The temporary tables created with 'CREATE TEMPORARY TABLE ...' should not be forgotten. The performance of InnoDB or MyISAM for temporary tables can have quite some impact, especially with slow storage, a buffer pool which is too

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MySQL 5.6 Performance Schema is GA
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The PERFORMANCE SCHEMA was first introduced in MySQL 5.5, and provided some instrumentation.

With MySQL 5.6, the existing instrumentation has been improved a lot, and a lot of new instrumentation was added also.

Now is a good time to review the overall picture ...

The performance schema tables


In 5.5, the tables available are:

mysql> show tables;
+----------------------------------------------+
| Tables_in_performance_schema                 |
+----------------------------------------------+
| cond_instances                               |
|









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10 Newer Entries Showing entries 31 to 40 of 76 10 Older Entries

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