Re: PostgreSQL ignores my indexes

Andrew Sullivan wrote:
> This is probably better on -performance, and is certainly a FAQ.
> But. . .
>
> On Wed, Feb 23, 2005 at 03:01:52PM +0100, Thomas Braad Toft wrote:
> >
> > Table device contains 5285 rows, tmeevent contains 834912 rows.
> ^^^^ ^^^^^^
>
> > -> Seq Scan on tmeevent (cost=0.00..23606.12 rows=834912 width=138)
> > (actual time=0.04..2193.97 rows=834912 loops=1)
> ^^^^^^
>
> > -> Seq Scan on device (cost=0.00..564.85 rows=5285 width=29) (actual
> > time=0.04..25.07 rows=5285 loops=1)
> ^^^^
>
> > Why isn't the planner using my indexes? I tried making them as both rtree
>
> Because there's no advantage to using an index when you are fetching
> 100% of both tables. This is the most efficient plan. Of course,
> it's an open question whether you want to get 100% of both tables.
> But that's what you're doing, and using the index would be more
> expoensive than this.

Right. The FAQ addresses this issue.

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