Re: Question about indexes

On Tue, Sep 9, 2008 at 10:52 AM, regme please <regmeplease(at)gmail(dot)com> wrote:
> Hi all.
> I usually create indexes accordingly to the queries used in my software.
> This means the more often than not I have composited indexes over more than
> one column.
> What'd be in PGSQL (v8.3+) the pros and cons of having instead only
> one-column indexes?
> Thanks in advance.

Pro:
Fewer number of smaller well traveled indexes (more efficient from
cache perspective).

Con:
Operations that look up multiple fields simultaneously run slower
(sometimes much slower).

Note that when reviewing sql written by other people in the
performance list, probably the most common optimization suggestion is
to use composite indexes.

merlin