While many people are familiar with the MySQL EXPLAIN command, fewer people are familiar with “extended explain” which was added in MySQL 4.1 EXPLAIN EXTENDED can show you what the MySQL optimizer does to your query. You might not know this, but MySQL can dramatically change your query before it actually executes it. This process […]
MySQL supports two different algorithms for views: the MERGE algorithm and the TEMPTABLE algorithm. These two algorithms differ greatly. A view which uses the MERGE algorithm can merge filter conditions into the view query itself. This has significant performance advantages over TEMPTABLE views. A view which uses the TEMPTABLE algorithm will have to compute the […]
MySQL 5.1 introduces row based binary logging. In fact, the default binary logging format in GA versions of MySQL 5.1 is ‘MIXED’ STATEMENT*; The binlog_format variable can still be changed per sessions which means it is possible that some of your binary log entries will be written in a row-based fashion instead of the […]
I often hear suggestion to use
system call to avoid caching in OS cache. We recently made patch for
, which supposes to create archive without polluting OS cache, as like in case with backup, you do not really expect any benefits from caching. However working on the patch, I noticed, that
Did that ever happen to you in production?
[percona@sandbox msb_5_0_87]$ ./use
ERROR 1040 (00000): Too many connections
Just happened to one of our customers. Want to know what we did?
A while back Friendfeed posted a blog post explaining how they changed from storing data in MySQL columns to serializing data and just storing it inside TEXT/BLOB columns. It seems that since then, the technique has gotten more popular with Ruby gems now around to do this for you automatically.
There was a discussion on LinkedIn one month ago that caught my eye: Database search by “within x number of miles” radius? Anyone out there created a zipcode database and created a “search within x numer of miles” function ? Thankful for any tips you can throw my way.. J A few people commented that […]
I recently had the chance to witness the effects of innodb_adaptive_flushing on the performance of InnoDB Plugin 1.0.5 in the wild, which Yasufumi wrote about previously here and here. The server in question was Solaris 10 with 8 disk RAID10 and 2 32GB SSDs used for ZIL and L2ARC, 72G RAM and 40G buffer pool. […]
I wrote a post a while back that said why you don’t want to shard.Â In that post that I tried to explain that hardware advances such as 128G of RAM being so cheap is changing the point at which you need to shard, and that the (often omitted) operational issues created by sharding can […]
This is part 3 of my Tyrant extra’s, part 1 focused on durability, part 2 focused on the perceived performance wall. #3.Â Tokyo Cabinet Can have only a single writer thread, bottlenecking performance When writing an application using Tokyo Cabinet only one connection can be opened as a â€œwriterâ€Â while the rest are readers.Â Tyrant […]