-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 01/08/07 20:39, Tom Lane wrote: > John Sales <spelunker334@xxxxxxxxx> writes: >> By doing this, I'm hoping that the query optimizer is smart >> enough to see that if a query comes in and requests only the >> six columns (that are in the narrower table) that PostgreSQL >> won't have to load the wider table into the buffer pool, and >> thereby actually have to only access about 10% the amount of >> disk that it presently does. > >> Is this a sound theory? > > No. It still has to touch the second table to confirm the > existence of rows to join to. But if a query /requests *only* the six columns (that are in the narrower table)/, why will the optimizer care about the other 224 columns? -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFFo5ZfS9HxQb37XmcRAtDRAJ41kKEN1Dv1iKXosTjy6IvMZKGccACfcZc9 e4pV+u0uLFisHcLu/gyuCvE= =q44l -----END PGP SIGNATURE-----
