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From:Matt W Date:December 18 2003 1:15am
Subject:Re: high water mark
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Hi Jamie,

Yes, when tables are made "smaller" in MySQL, the file size isn't
actually reduced. I guess it shouldn't usually make a speed difference
unless your SELECTs are doing a table scan. Reads that use an index
shouldn't really be affected, I don't think.

If you want to reclaim the deleted space, you can do so by running
OPTIMIZE TABLE.  Be aware that it may take awhile to run on a large

Hope that helps.


----- Original Message -----
From: "jamie murray"
Sent: Wednesday, December 17, 2003 2:42 PM
Subject: high water mark

Does mysql record the high water mark in it's tables. If so can it be
shrunken after a mass delete. I am new to mysql and haven't seen any
info on this so I'm not sure if it exists in this database. I am asking
this because after I deleted a lot of data from one table a simple
select is now very slow, this would make me think that like in oracle
the query is reading all blocks up to the high water mark even thought
there is no data there.
I am familiar with oracle but not MySql so excuse my ignorance if it is
showing with this particular topic.


Re: high water markMatt W18 Dec