Search Results for: innodb select count slow

InnoDB: look after fragmentation

One problem made me puzzled for couple hours, but it was really interesting to figure out what’s going on. So let me introduce problem at first. The table is

Table has 11864696 rows and takes Data_length: 698,351,616 bytes on disk The problem is that after restoring table from mysqldump, the query that scans data […]

InnoDB benchmarks

There was several changes in InnoDB to fix scalabilty problems, so I ran benchmark to check new results and also compare overall performance of InnoDB in 5.0 and 5.1 before and after fixes. Problems in InnoDB that were fixed: Thread trashing issues with count of theads 100+. In this case performance of InnoDB degraded dramatically. […]

SHOW INNODB STATUS walk through

Many people asked me to publish a walk through SHOW INNODB STATUS output, showing what you can learn from SHOW INNODB STATUS output and how to use this info to improve MySQL Performance. To start with basics SHOW INNODB STATUS is command which prints out a lot of internal Innodb performance counters, statistics, information about […]

Why MySQL could be slow with large tables ?

If you’ve been reading enough database related forums, mailing lists or blogs you probably heard complains about MySQL being unable to handle more than 1.000.000 (or select any other number) rows by some of the users. On other hand it is well known with customers like Google, Yahoo, LiveJournal,Technocarati MySQL has installations with many billions […]

Innodb Fuzzy checkpointing woes

As you might know Innodb storage engines uses Fuzzy Checkpointing technique as part of it recovery strategy.  It is very nice approach which means database never needs to “stall” to perform total modified pages flush but instead flushing of dirty pages happens gradually in small chunks so database load is very even. This works great […]