by Peter Zaitsev | Jul 8, 2007 | Insight for DBAs
In my previous post I mentioned you might need to increase net_write_timeout to avoid connection being aborted and now I think I should have better explained that. MySQL uses a lot of different timeout variables at different stages. For example when connection is just...
by Peter Zaitsev | Jul 6, 2007 | Insight for Developers
We’re working with web site preparing for massive growth. To make sure it handles large data sets as part of the process we work on generation test database of significant size as testing your application on table with 1000 rows may well give you very dangerous...
by Peter Zaitsev | Jul 5, 2007 | Insight for Developers
What does working with large data sets in mySQL teach you ? Of course you have to learn a lot about query optimization, art of building summary tables and tricks of executing queries exactly as you want. I already wrote about development and configuration side of the...
by Peter Zaitsev | Jul 1, 2007 | Insight for Developers
On many web sites you would see a counter how many time given object – blog post, forum thread, image, movie etc was viewed. This is sometimes handy feature but it can be rather expensive from performance point of view. The nasty thing with counters as they are...
by Peter Zaitsev | Jun 26, 2007 | Insight for DBAs
I ran into pretty interesting behavior today. We needed to dump and reload large database and we had pretty good IO subsystem so we started number of mysqldump processes in parallel. Unlike in other case when we did load in parallel, dump in parallel did not increase...
by Peter Zaitsev | Jun 25, 2007 | Insight for DBAs
One may think one may use MySQL Slow query log to log all slow queries to catch problematic queries or for audit purposes. In fact however not all the queries are logged. I already mentioned mysql slave queries are not logged to slow query log and it looks like I was...
by Vadim Tkachenko | Jun 6, 2007 | Insight for DBAs
Just short message that patch enables microsecond resolution in slow-log (see more https://www.percona.com/blog/2006/09/06/slow-query-log-analyzes-tools/) for 5.0.37 is available here: www.percona.com/blog/files/patches/patch.slow-micro.5.0.37.diff The patch for...
by Peter Zaitsev | May 24, 2007 | Insight for DBAs
I had this question asked many times during last week, and there is really no easy answer. There are just way too many variables to consider especially while loading large schemas with a lot of different table structures. So which variables affect the load speed:...
by Peter Zaitsev | Mar 15, 2007 | Insight for DBAs
Looking at post by Konstantin Osipov we should finally get Query Cache working with prepared statements in MySQL 5.1 The interesting thing Konstantin notes it just took few days to fix it – I believe MySQL Support Team alone spent much more times explaining...
by Peter Zaitsev | Mar 7, 2007 | Insight for DBAs
Today I was cloning the master using LVM Snapshot and found it was taking quite a while to catch up, which highlighted replication could be the limiting factor for this system quite soon, so I decided to check what is limiting MySQL Replication speed. My first idea...
by Peter Zaitsev | Feb 27, 2007 | Insight for Developers
Performance optimization is never ending story, you can virtually always find something else to optimize but while on generic system, not tuned by expert you often can get significant performance increase in the matter of hours further performance improvements become...
by Peter Zaitsev | Feb 11, 2007 | Insight for Developers
This week I helped dealing with performance problems (part MySQL related and part related to LAMP in general) of system which does quite a bit of content delivery, serving file downloads and images – something a lot of web sites need to do these days. There were...
by Peter Zaitsev | Feb 8, 2007 | Insight for DBAs, MySQL
Have you ever seen a connection in the SHOW PROCESSLIST output which is in “Sleep” state for a long time and you have no idea why this would happen? MySQL Sleep I see if frequently with web applications and it is often indication of trouble. Not only it...
by Peter Zaitsev | Feb 5, 2007 | Insight for Developers
I already wrote kind of about same topic a while ago and now interesting real life case makes me to write again 🙂 Most Web applications we’re working with have single tier web architecture, meaning there is just single set of apache servers server requests and...
by Peter Zaitsev | Jan 30, 2007 | Insight for DBAs
Kevin Burton writes about making MySQL Replication Parallel. Many of us have been beaten by the fact MySQL Replication is single threaded so in reality it is only able to use only single CPU and single disk effectively which is getting worse and worse as computers are...
by Peter Zaitsev | Jan 19, 2007 | Insight for DBAs
We all know disk based temporary tables are bad and you should try to have implicit temporary tables created in memory where possible, do to the fact that you should increase tmp_table_size to appropriate value and avoid using blob/text columns which force table...
by Peter Zaitsev | Jan 18, 2007 | Insight for Developers
Jonathan Haddad writes about REPLACE INTO and INSERT ON DUPLICATE KEY UPDATE. Really, Why MySQL has both of these, especially both are non ANSI SQL extensions ? The story here seems to be the following – REPLACE INTO existed forever, at least since MySQL 3.22...
by Peter Zaitsev | Jan 17, 2007 | Insight for Developers
What is often underestimated is impact of MySQL Performance by complex queries on large data sets(ie some large aggregate queries) and batch jobs. It is not rare to see queries which were taking milliseconds to stall for few seconds, especially in certain OS...
by Vadim Tkachenko | Jan 12, 2007 | Percona Events
Update 3 June 2008: We have removed the builds below, since they are quite obsolete and no one has posted comments about them since more than a year ago. Great news are MySQL finally released new Community release – MySQL 5.0.33, which however as promised comes...
by Peter Zaitsev | Jan 9, 2007 | Insight for Developers
I had a fun case today. There is set of cache tables which cache certain content in MyISAM tables and queries for these tables such as: select data from cache0003 where `key`=2342526263 and real_key='cp_140797_6460aad5d2e50d3e859e8649007686ac'; 1 select data from...
