…of threads for a benchmark that runs for a long time? I answered that in my previous post on choosing… actually ran some other thread counts for durations of a few hours at a time. For example, I benchmarked …that it is ready to publish on this blog takes a lot of care. Instead, during the benchmarks …
Post: Why Swapping is bad for MySQL Performance ?
January 18, 2010 By 11 Comments
… is obvious. But how bad is it ? Should you count it same as normal Disk IO as the box… IOs take a long time. When system is swapping all of these gets messed up – when database is thinking it is taking… spike you may prefer to see slowdown instead of MySQL being killed because of out of memory but do…
Post: Faster MySQL failover with SELECT mirroring
February 1, 2009 By 9 Comments
…in both directions. Aside from MySQL Cluster, which is more special-…master for serving some SELECT queries, taking backups, etc as usual. However,…it can be completely unusable for a long time. To measure how much this …_schema, table_name, page_type, count(*) from information_schema.innodb_buffer…
Post: Identifying the load with the help of pt-query-digest and Percona Server
December 29, 2011 By 3 Comments
… new connections as in MySQL. This is very helpful for measurement as otherwise we might not catch some long running connections. Now… is taking up the longest sum of run time, query ranked #1. The first row in the table above shows the Count of number of times this query was executed. Now let’s take a look at the values…
Post: The two even more fundamental performance metrics
May 5, 2011 By 6 Comments
… take about the same time to process and send back the response, with a “long tail” of requests that take…time is under a millisecond — maybe it’s 50 microseconds, maybe a bit longer. This is common in MySQL…and completions into buckets, a second at a time, and count how many there are in each bucket,…
Post: How much memory Innodb locks really take ?
July 13, 2006 By 11 Comments
…_free: 0 Auto_increment: 1638401 Create_time: 2006-07-12 07:31:51 Update_time: NULL Check_time: NULL Collation: utf8_general_ci… how long does it take: mysql> begin; Query OK, 0 rows affected (0.00 sec) mysql> select count(i) from sample lock in share mode; +———-+ | count… much exclusinve locks take: mysql> begin; Query OK, 0 rows affected (0.00 sec) mysql> select count(i) from sample for update; +———-+ | count(i) | +———-+ | 1638400…
Post: How fast is FLUSH TABLES WITH READ LOCK?
April 24, 2010 By 30 Comments
… their MySQL backup…Time | State | Info | +—-+——+———–+——+————+——+——————-+———————————————————————-+ | 4 | root | localhost | test | Query | 80 | Sending data | select count…take a long time to flush. During that time…
Post: UDF -vs- MySQL Stored Function
September 6, 2010 By 8 Comments
…long it took to process 100k rows: mysql> select ltrim_junk_mysql(author), ltrim_junk_mysql…mysql> select count(*) from paintings where title != ltrim_junk(title); +———-+ | count(*) | +———-+ | 101533 | +———-+ 1 row in set (6.82 sec) mysql> select count…
Post: A workaround for the performance problems of TEMPTABLE views
May 19, 2010 By 7 Comments
… | count(*) | +——+———-+ | 10 | 130 | +——+———-+ 1 row in set (1.66 sec) Even a query with an impossible where clause takes a long time to process: mysql> select * from v2 where c1 = 100; Empty set (1.64 sec) You can see that MySQL is…
Post: Faster Point In Time Recovery with LVM2 Snaphots and Binary Logs
February 23, 2012 By 3 Comments
…taking a consistent backup of your MySQL…mysql-bin.000022 | mysql mysql> select count(*) from salaries where emp_no = 10001; +———-+ | count(*) | +———-+ | 0 | +———-+ 1 row in set (0.00 sec) mysql…
