A question for you MySQL gurus out there:
Currently, the categorylinks table uses the index
cl_sortkey(cl_to,cl_sortkey(128)),
Note that the cl_sortkey field in the table is varchar(255).
In the categoryPage query, there is an ORDER BY clause on cl_sortkey.
However, this query ends up using a filesort. I've found that if the
index is changed to use the full width of the cl_sortkey field, then
the ORDER BY does not need the filesort.
Does anyone know how to eliminate the need for a filesort without
having to expand the index to the full width of cl_sortkey? Or should
we just bite the bullet and use the full width?
I've tried ORDER BY LEFT(cl_sortkey,128), but that doesn't help
(probably no big surprise).
-Rich Holton
en.wikipedia:User:Rholton