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Re: unexpected index growth
It doesn't look like it is the long running transactions. For about 15 minutes, we made sure no transaction was running for than 5 minutes. During this time, the size of the index didn't shrink. Does innodb purge out old records from the index on a periodic basis ? If so, when does this happen?
Last time we fixed this, we did so by running an optimize table, is there a way to rebuild an index without having to either recreate it or run optimize table ?
----- Original Message -----
From: "Sergei Golubchik" <serg@xxxxxxxxxxxx>
To: "Said Ramirez" <sramirez@xxxxxxxxxxxx>
Cc: "Maria Discuss" <maria-discuss@xxxxxxxxxxxxxxxxxxx>
Sent: Monday, March 11, 2013 11:14:11 AM
Subject: Re: [Maria-discuss] unexpected index growth
On Mar 11, Said Ramirez wrote:
> The longest transaction I currently see is ~ 3.5 hours. Which is a
> long time, and I can look into to that. I haven't seen transactions
> last days yet. Would having a transaction last hours not cause the old
> rows from being purged once those transactions have closed? If it
> were an old or stale transaction keeping the old row versions from
> being purged, a server restart would fix the issue, no ?
Yes, a long lasting transaction would prevent old row version from being
purged even after those transactions have ended. Because a default
transaction isolation level is consistent read, which means, that if
you've seen some version of a row in a transaction, you should always
continue seeing this exactly version of this row until your transaction
ends. And InnoDB will have to keep this version and it cannot purge it.
Yes, a server restart would fix it.
> We also do see a fair amount of deadlocks. Could a thread that is
> causing the deadlock cause old row versions from being purged even
> after the this thread is closed?