Weird situation, tuning a MySQL db and query, what creates tmp files?

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05:53 pm January 26th, 2009

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			Mark Atwood

fallenpegasus


	Weird situation, tuning a MySQL db and query, what creates tmp files?
	I'm trying to figure out for a friend what results in something like this Restart the MySQL server and then run the query once. Then check the status variables. Created_tmp_disk_tables = 0 Created_tmp_files = 362 Created_tmp_tables = 2 Sort_scan = 0 Sort_merge_passes = 0 What could be creating all those tmp files? It's not sorting on disk.... Tags: mysql

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	From: arjen_lentz	Date: January 27th, 2009 02:14 am (UTC)		(Link)
	more info needed...

Might be handy to see the query.

Also, you can just do SHOW SESSION STATUS to see the counters within a connection rather than the global cumulative.

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	From: awfief	Date: January 27th, 2009 02:48 am (UTC)		(Link)

Replication. USD $10 says that this is a slave server.

If the query was larger than MIN(tmp_table_size,max_heap_table_size), it would sort on disk and increase the Created_tmp_disk_tables variable, not Created_tmp_files.

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