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MySQL Feed

Oracle MySQL resources, news, and support articles.

kernel_mutex problem. Or double throughput with single variable

Problem with kernel_mutex in MySQL 5.1 and MySQL 5.5 is known: Bug report. In fact in MySQL 5.6 there are some fixes that suppose to provide a solution, but MySQL 5.6 yet has long way ahead before production, and it is also not clear if the problem is really fixed.

Meantime the problem with kernel_mutex is raising, I had three customer problems related to performance drops during the last month.

So what can be done there ? Let’s run some benchmarks.

More MySQL foreach()

In my previous post I've shown several generic use cases for foreach(), a new scripting functionality introduced in common_schema.

In this part I present DBA's handy syntax for schema and table operations and maintenance.

Call for participation for MySQL events - MySQL conference and FOSDEM

It's that time of the year where MySQL would be speakers are called to action. As usual, the main event is the MySQL spring conference, this year hosted by Percona. The call for participation to the MySQL Conference And Expo 2012 is still open until December 5th. To submit a proposal, you should register as a speaker and then fill in the form.

MySQL foreach()

A new routine is now available in common_schema, which makes for an easier execution syntax for some operations:

foreach(collection_to_iterate_over, queries_to_execute_per_iteration_step);

To illustrate what it can do, consider:

Automatically detecting abnormal behavior in MySQL

Over the course of years, I have observed that the three most sensitive indicators of MySQL having a server lockup are the queries per second, number of connections, and number of queries running. Here is a chart of those three on a production system. Find the bad spot:

Common Schema: dependencies routines

Are you a MySQL DBA? Checkout the common_schema project by Oracle Ace Shlomi Noach.

common_schema, rev. 178: foreach(), repeat_exec(), Roland Bouman, query analysis

common_schema, revision 178 is now released, with major additions. This revision turns common_schema into a framework, rather than a set of views and functions.

Never say "there is no way"

Reading a recent MySQL book, I saw an example of SHOW CREATE TABLE that comes with backticks (`) around the table and column names, and a comment:

Unfortunately, there is no way to remove this from generated syntax with this command.

(Emphasis mine).
Here's how it goes:

mysql> show create table mytest\G
*************************** 1. row ***************************
Table: mytest
Create Table: CREATE TABLE `mytest` (
`id` int(11) NOT NULL,
`description` varchar(50) DEFAULT NULL,

Special mysqldump fingerprinting rule in pt-query-digest

The pt-query-digest tool has a number of special cases that affect how it “fingerprints” queries when it groups similar queries together to produce an aggregated report over the group. One of these is a special rule for queries that appear to come from mysqldump, of the following form:

Percona Live: MySQL Conference And Expo 2012 - a note on proposals

As a member of the conference committee I review the session and tutorial proposals for the Percona Live MySQL conference in Santa Clara, 2012.

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