0
votes
0answers
45 views

Rails with mysql 5.5 update queries take long

app was running Rails and MySQL 5.1 and worked quite well. When we have upgrade to the new server with MySQL 5.5 some update and delete queries started to work quite long (1 sec vs 50ms on old ...
1
vote
2answers
97 views

Is there a rule of thumb regarding the size and number of a buffer pool instances?

I know the consensus seems to be approximately 75% of ram should be dedicated to the buffer pool. But, I'm more interested in the optimal number of buffer pool instances. What are some things to ...
2
votes
1answer
1k views

MySQL: Alter Table on very active table gives “Waiting for table metadata lock”

At my work, we've recently upgraded to MySQL 5.5 and since then, have been bitten a few times by the new (and intended) behavior of metadata locking. Basically, whenever we run an ALTER TABLE ...
5
votes
2answers
173 views

DELETE LOW_PRIORITY row visibility

I have a large MyISAM table on MySQL 5.5(Windows XP x64) on which I will have to run DELETE LOW_PRIORITY queries. Does DELETE LOW_PRIORITY make the rows invisible to SELECT statements immediately and ...
4
votes
2answers
18k views

way to prevent queries from waiting for table level lock

We've encountered a problem after moving the database of our customer to an extra server. This should have had positive effects on the site's performance, but there is a problem with table locking in ...