
	Hello:

	I am trying to find out, how is the B-tree index implemented for
multiple columns? does Postgres, just
	concatenate the columns --- if this is the case, then how is the
search performed? Also, does the optimizer
	choose the index, only when the constraining is on the leading
subset of the index column?

	Thanks
	VJ 

Wed, 3 Dec 2003 10:18:52 -0600 
"Anand, VJ (MED, GEMS-IT)" <Virinchipura.Anand@med.ge.com>
BTree index and optimizer
Anand, VJ (MED, GEMS-IT) kirjutas K, 03.12.2003 kell 18:18:
> 	Hello:
> 
> 	I am trying to find out, how is the B-tree index implemented for
> multiple columns? does Postgres, just
> 	concatenate the columns --- 

Yes.

> if this is the case, then how is the
> search performed? Also, does the optimizer
> 	choose the index, only when the constraining is on the leading
> subset of the index column?

Yes.

If you want it more complicated, you could check out if PG's R-tree
indexes suit you.

-------------
Hannu


Thu, 04 Dec 2003 12:28:51 +0200
Hannu Krosing <hannu@tm.ee>
Re: BTree index and optimizer