Re: [PHP] database abstraction layer

Rene Veerman wrote:
> i haven't had the pleasure yet of writing for sites that generate so many
> hits/sec that
> they'd update the max value of any table at exactly the same time.
> 
> i usually ask for the max value about 2 milliseconds before doing the
> insert.
> And if the insert fails, i can auto-retry via a wrapper function after
> sleep(rand(1,3));
> I dare say i could work this way at facebook <g> (not that i really want to,
> happy with where i am)

This is a race condition... all you need are two hits per day... one 
from person A and one from person B. If they happen within short enough 
temporal proximity then the race is on.

Now... a big fat lock around the table before the request for max ID and 
the insert query ought to mitigate your issue. Although I wouldn't call 
my function getMaxId() I would call it getNextId() :)

Cheers,
Rob.
-- 
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