I gots to know…

Big web companies who use MySQL – what isolation level(s) do you use? Do you take the default? Do you think about it at all? How about if you use, eg, memcached, what there? And, does your code think about optimistic or pessimistic locking?

I’ve been reading up on isolation levels after seeing Peter Bailis’
http://www.bailis.org/blog/understanding-weak-isolation-is-a-serious-problem/
(thanks to Mark Callaghan for re-tweeting about it).

I’m learning things…  here’s one for today –

I always thought that the “repeatable” in repeatable read applied to the data in general. Meaning that a query run twice in a transaction would “repeat” the same results. I guess it actually is supposed to apply to records?  Ie, other transactions’ updates to an …

Have you downloaded our eBook, Building Database Driven Apps with Go? It is the best resource to quickly learn how to connect a database from Go programs.

This excerpt presents a quick introduction to the major functionality of database/sql in the form of a fully functioning Go program.

Before you begin, ensure you have access to a MySQL database, as we’ll use MySQL for the example. If you don’t have an instance of MySQL that’s appropriate for testing, you can get one in seconds with the MySQL Sandbox utility.

Create a new Go source file, hello_mysql.go, with the following source code (download). You may need to adjust the connection parameters as needed to connect to your testing database. Note …

With the changes to performance_schema in MySQL 5.7 Development Milestone Release it is now possible to analyze and profile the execution of stored programs. This is highly useful if you develop more complex stored procedures and try to find the bottlenecks. The "old" performance_schema up to MySQL 5.6 only reported a CALL statement with a runtime, but no information on statements that were executed WITHIN the stored procedure. Now let's try this in the latest MySQL 5.7.6 DMR release. After creating some test table and a test stored procedure we need to activate the events_statements_history_long consumer, which is OFF by default:

mysql> UPDATE setup_consumers SET ENABLED="YES" 
           WHERE NAME = "events_statements_history_long"; 

Then let's call the stored procedure that we want to inspect:

mysql> CALL …

On Thursday I’ll be hosting a webinar explaining how you can get the best from the NoSQL world while still getting all of the benefits of a proven RDBMS. As always the webinar is free but please register here.

Even if you can’t join the live webinar, it’s worth registering as you’ll be emailed a link to the replay as soon as it’s available.

Abstract

There’s a lot of excitement about NoSQL data stores, with the promise of simple access patterns, flexible schemas, scalability, and high availability. The downside comes in the form of losing ACID transactions, consistency, flexible queries, and data integrity checks. What if you could have the best of both worlds? Join this webinar to learn how MySQL …

As of meb-3.12.0, the cloud options take precedence, i.e. specifying any of the "--cloud-*" options makes MEB treat it as a cloud operation.

The backup file name to be used on the cloud is to be specified by a "--cloud-" option. Any value represented by "--backup-image=<value>" is not interpreted by MEB(in case of cloud operations), and the above commands would work correctly as expected.

I agree, this dependency on the unused option of "--backup-image=<value>" can be done away with, if possible and thanks a lot for pointing it.

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 which these tokens were considered for the digest calculation was previously fixed at 1024 bytes. Which meant that while reading the tokens, once 1024 bytes were read from statement’s token stream, only that many tokens were considered when generating the …

Percona Toolkit is one of our most mature open source applications. Derived from Maatkit and Aspersa, Percona Toolkit has evolved significantly over the years. The software now contains 32 tools, over 4,000 tests, and has been downloaded over 250,000 times. Anyone who manages a database – from DBAs to system administrators to even software developers – benefits from Percona Toolkit’s ability to perform a variety of MySQL server and system tasks that are too difficult or complex to perform manually.

We continue to make Percona Toolkit better each month. Over the last 9 months alone Percona has had 6 releases and resolved nearly 50 issues.

…

My former boss, Marten Mickos, has created an excellent new resources for early stage founders, managers and execs called www.Schoolofherring.com. Each post has a short write up and often a 2-3 minute video covering a topic such as giving feedback, Peter Drucker's principles of good management, what it takes to build an effective team, hiring for strength etc. Some of these topics are very practical, like how to send good email, others are more thought-provoking, such as the notion that …

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 setup_actors table in order to specify what users and hosts you want to have instrumentation enabled for.

But what about the case where you want to enable instrumentation for everyone except the …

In developing MySQL Server and MySQL Cluster we use four types of testing.
We use unit testing, we use functional testing, we use system testing and
we use benchmark testing.

For the unit tests and functional tests we use the MTR test framework. This
is dealing with most issues of how to use SQL to query the MySQL database
engine.

For system testing the InnoDB team has a test framework that is used to ensure
that InnoDB will survive crashes of many sorts. In a similar fashion MySQL
Cluster uses the autotest framework that I described in an earlier blog:
Link to earlier blog.

For benchmark testing we have a few frameworks, I am going to describe the one
that I use on a regular basis. This framework can be downloaded from:
…