I posted a simple INFORMATION_SCHEMA query to find largest tables last month and it got a good response. Today I needed little modifications to that query to look into few more aspects of data sizes so here it goes:
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What MySQL honestly was never good at is giving good helpful error messages. Start with basics for example – The error message in case of syntax error gives you information about tokens near by but little details:
Shell
mysql> select * from user oder by pwd;
ERROR 1064 (42000): You have an error in […]
For large number of online applications once you implemented proper sharding you can consider your scaling problems solved – by getting more and more hardware you can grow. As I recently wrote it however does not mean it is the most optimal way by itself to do things.
The “classical” sharding involves partitioning by […]
I think every person responsible for Development or Operations of growing application sooner or later have to decide on couple few questions on how to tackle application performance. These questions are:
Should we Optimize Application or get more Hardware ?
Should we do things ourselves or hire an experts to help us ?
The answer on […]
Read moreI’ve been waving my hands about lower bounds. Well, sometimes I haven’t been waving my hands, because the lower bounds are tight. But in other cases (lenient insertions, range queries), the lower bounds are very far from what we’re used to.
So now, for a bit of math:
Brodal and Fagerberg showed in 2003 […]
Doing performance analyzes today I wanted to count how many hits come to the pages which get more than couple of visits per day. We had SQL logs in the database so It was pretty simple query:
Shell
select sum(cnt) from (select count(*) cnt from performance_log_080306 group by page having cnt>2) pv;
1
select sum(cnt) from (select […]
Read moreAndrew Aksenoff is pretty slow with release numbers for Sphinx. By MySQL Users Conference 2007 Sphinx version 0.9.7 was released and today we had just 0.9.8-rc1 announced This minor change in version number corresponds to about double source size (looking at download size) and major rewrite for […]
Read moreI’m often asked how one can evaluate IO subsystem (Hard drive RAID or SAN) performance for MySQL needs so I’ve decided to write some simple steps you can take to get a good feeling about it, it is not perfect but usually can tell you quite a lot of what you should expect […]
Read moreImplementing MySQL database in 24/7 environments we typically hope for uniform component performance, or at least would like to be able to control it. Typically this is indeed the case, for example CPU will perform with same performance day and night (unless system management software decides to lower CPU frequency due to overheating).
This […]
Sorry for the delay, now on to range queries and lenient updates. Let’s call them queries and updates, for short. So far, I’ve shown that B-trees (and any of a number of other data structures) are very far from the “tight bound.” I’ll say a bound is a tight if it’s […]
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