Thomas Hallgren wrote:
Christopher Kings-Lynne wrote:
Is it worth allowing this:
select count(*) from users_users where position('ch' in username) = 0;
To be able to use an index, like:
select count(*) from users_users where username like 'ch%';
At the moment the position() syntax will do a seqscan, but the like
syntax will use an index.
You must compare position('ch' in username) to '%ch%' instead of 'ch%'
in this respect.
The position function must look for 'ch' everywhere in the string so
there's no way it can use an index.
I think the '= 0' bit is what Chris was suggesting could be the basis
for an optimisation.
Tim
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Tim Allen [EMAIL PROTECTED]
Proximity Pty Ltd http://www.proximity.com.au/
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