josh at agliodbs.com
Fri Sep 21 13:13:03 UTC 2007
> Yes, but it's probably built in to your language and thus an awful lot
> faster to do an isset() / in_array() or array_key_exists() (PHP) on an
> array that you have in hand than to have a trip to the DB. In fact the
> language may index arrays internally anyway. MySQL with an index will be
> faster than MySQL without an index, but it will still be much slower
> than local array searching.
Well, that's going to depend on the numbers we're talking about; I'd
imagine that, *assuming the data and index was already cached in
memory*, a good DB would do a better job of pulling a select 100 entries
out of 2,000,000. But out of 200? No. Where the tipping point is
would depend on more factors than I want to put into an e-mail.
In any case, this is highly hypothetical. I think you'll find that 99%
of your users have < 50 friends, so why optimize for the special case?
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