Re: Index usage on OR queries

On Wed, Aug 31, 2011 at 4:49 PM, Andy Colson <andy(at)squeakycode(dot)net> wrote:

> On PG 9, after I ANALYZED the tables, it used indexes:
>
>
> QUERY PLAN
> ------------------------------**------------------------------**
> ------------------------------**---------------------
> Merge Join (cost=1.59..82778.35 rows=13171 width=20) (actual
> time=0.066..1076.616 rows=12966 loops=1)
> Merge Cond: (a.id = b.id)
> Join Filter: ((a."time" >= '2011-08-15 00:00:00'::timestamp without time
> zone) OR (b."time" >= '2011-08-01 0
> -> Index Scan using a_pkey on a (cost=0.00..31389.36 rows=1000000
> width=12) (actual time=0.007..204.856 ro
> -> Index Scan using b_pkey on b (cost=0.00..31389.36 rows=1000000
> width=12) (actual time=0.006..224.189 ro
>
>
> ANALYZE is the magic.
>

You are, of course, right, but it doesn't use the TIME index.
Hmmm, may be my example isn't large enough to produce the issue.

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