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From:Michael Widenius Date:March 30 1999 8:51pm
Subject:Big select filling file system
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>>>>> "Eric" == Eric D Patterson <slacker@stripped> writes:

Eric> I am attempting to run this query on a table consisting of 2M rows:
Eric> SELECT DISTINCT part_no,MDealer,Dealer,Model,Orig_Part from parts;

Eric> I know it's going to be nasty on the server, but really want to do it
Eric> anyway, and run into the following problem:

Eric> Mysql is dumping 300+Mb of data to my root partition, filling it, and
Eric> causing problems from there on, and I have not been able to find exactly
Eric> where these files are, or what they contain. (though i assume they are
Eric> temp files getting dumped there for some reason)

Eric> Server specs:
Eric> runnig mysq 3.22.16a-gamma
Eric> DEC alpha (in case it matters)
Eric> DEC UNIX
Eric> / partition is 500Mb, with ~300Mb free
Eric> 512Mb ram, normally 86% free

Eric> Does anybody know what these files are, or more importantly, how to make
Eric> it not do this?
Eric> --If so, please drop me an email at: slacker@stripped

Fix:

Start mysqld with --tmpdir=path-to-another-partition

or

Increase the mysqld sort_buffer;  This will make MySQL use less
temporary place!

To execute the above select, MySQL will need temporary space to store
2 copies of the data for:

part_no,MDealer,Dealer,Model,Orig_Part,'longint'

Regards,
Monty
Thread
Big select filling file systemEric D. Patterson30 Mar
  • Big select filling file systemMichael Widenius31 Mar