Hi all,
A silly idea:
a composite index on objectId, subChunkId (beware the order)
may avoid to create a temporary table for each subChunkId?
Here's an interesting documentation about the weird behaviour of
MySQL query optimizer:
http://dasini.net/blog/2009/02/18/optimisation-de-requetes-comprendre-loptimiseur-de-mysql/
And the official doc:
http://dev.mysql.com/doc/refman/5.0/en/multiple-column-indexes.html
FYI, Daniel and Jacek have ran some tests about it.
Cheers,
Fabrice
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