"scott.marlowe" <scott.marlowe@ihs.com> writes:
> Yes, previously run query should be faster, if it fits in kernel
> cache.
Or the PostgreSQL buffer cache.
> Plus, the design of Postgresql is such that it would have to do a
> LOT of cache checking to see if there were any updates to the
> underlying data between selects.
Last I checked (which was a while ago, admittedly), the MySQL design
completely purges the query cache for a relation whenever that
relation is mentioned in an INSERT, UPDATE, or DELETE. When this was
discussed (check the -hackers archives for more), IIRC the consensus
was that it's not worth implementing it if we can't do better than
that.
-Neil