Users are complaining about slowness in your system, MySQL load is always high… The more your database has access, the more it may get slow or worse: slowness even if it is running with low load. You are starting to get desperate! The consequences of slowness and high load are disastrous: If your site is slow,... Read More
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Today before Ivan’s tutorial, he told me that in the 10.0.5 virtual machine images he created, he couldn’t find the Cassandra storage engine. I told him it had to be installed separately, and this is true – you have to install some engines separately!
When you do a yum install MariaDB-server MariaDB-client like the installation instructions tell you to do, you don’t get all storage engines (so running SHOW ENGINES might have you wondering what happened to a bunch of engines). This can easily be seen by doing a yum search MariaDB. On a CentOS 6.4 server with the MariaDB 10.0 repository configured, you should see the following:
MariaDB-cassandra-engine.x86_64 : MariaDB: a very fast and robust SQL database server MariaDB-client.x86_64 : MariaDB: a very fast and robust SQL database server MariaDB-common.x86_64 : MariaDB: a very fast and robust SQL …[Read more]
Frequently in performance talks I hear speakers talk about the
importance of using the correct datatypes for storing values in
columns. i.e. representing a number with an INT or
BIGINT, storing IP addresses as INT
UNSIGNED, and VARCHAR(60) instead of
VARCHAR(255).
This advice is correct, but today I thought I would try my best to go into a bit more detail :)
The Reasons
I can think of three reasons why this optimization is true:
Using numeric data types as strings incurs some added CPU
overhead performing character-set and collation work. i.e.
it’s not free to make 'Montréal' = 'Montreal' =
'MONTREAL', but MySQL behaves this way by default.
Using correct data types will save space. By ‘space’ usually memory-fit is more important than disk fit, as it can …
Some years back I attended a talk on testing practices where the
presenter asked the audience how much test automation have they
achieved in their projects. I was the only one who answered
almost 100%. He advised me to keep this a secret from my
management if I did not want my team to be downsized :). Good
advice, but that got me thinking whether test automation actually
makes testers redundant.
Having spent a good part of my experience in testing, I have seen
this discipline mature over the years. My opinion is that
automation does not take away tester jobs; on the contrary it
makes the job more interesting and effective.
In my mind I classify automation progression in an
organization into 4 stages as shown below.
Stage 1 In stage 1, testing is a completely …
Join Web and Telecom companies who have adopted MySQL Cluster to facilitate application in the following areas:
Web:
Telecoms:
To come up to speed on MySQL Cluster, take the 3-day MySQL Cluster training course. Events already on the schedule include:
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8PM. One of the servers found a critical bug. Hop online and discuss, log bug. 10PM. Patch ready. 10:30PM. New build ready. 10:45PM. New RQG run initiated. This was by no means an uncommon sight during the months of testing that went into Percona Server 5.6, in fact it was commonplace.
At a certain point, we had 3 very high end servers (modern cpu’s, heaps of cores and memory), all equipped with either fast SSD’s or Fusion-io flash storage, executing thousands of trials, 8 in parallel per server, each executing 1 to 25 mysql threads per running mysqld instance.
And that was just the final months of testing. Before that much work was done on finding “every last bug out there”. We discovered many bugs in both upstream (Oracle’s MySQL 5.6) and in Percona Server 5.6. I personally logged around 100 bugs, but the total count would be much higher still.
My colleague …
[Read more]How do we ensure that, when we have 35+ testable option combinations for mysqld, we test each and every combination of them? For example: will a different innodb_log_file_size combined with more innodb_log_files_in_group and a modified innodb_fast_shutdown setting truly not affect Percona’s log archiving feature?
Most option-related bugs are caused by the setting of 1 or 2 mysqld options to a non-standard value. Maybe in an odd situation 3 mysqld options need to be set in combination. So, starting with 2 option combinations (1 option set is easy to calculate: it matches the number of options to be tested), let’s see how many combinations we would have to run: 35^2 = 1225 combinations. aa, ab, ac, …. ba, bb, bc… etc.
In real life mysqld testing, this is not entirely true as one would never specify “aa” in relation to …
[Read more]This post builds on the How to obtain the “LES” (Last Executed Statement) from an Optimized Core Dump? post written about a year ago.
A day after that post was released, Shane Bester wrote an improved version, How to obtain all executing queries from a core file on his blog. Reading that post is key to understanding what follows.
I am faced with some complex bugs which would do well with SQL testcases. Extracting the last executed statement (and maybe all queries running at the time of the crash/asserts) is crucial to generate testcases well. E.g. you may have a full SQL trace from RQG or …
[Read more]Me and some of my colleagues are giving MySQL talks at OSI days. Check out the schedule at http://osidays.com/osidays/open-source-india-day-3/. Hope to see you all there.
DB-Engines.com (http://db-engines.com/en/ranking/relational+dbms) ranks MySQL as the #2 most popular relational database after Oracle. MySQL is continuing to grow and gain market share. MySQL 5.6 and 5.7 show the database server is continuing to add significant new functionality in each release. MySQL is extremely fast and scalable. MySQL cluster can also perform well against the fastest
