[postgis-users] speeding up simple pt-in-poly lookups

[Paul Ramsey]

Chop up the continents into smaller pieces.

On Tue, Dec 20, 2011 at 4:35 PM, Puneet Kishor <punk.kish at gmail.com> wrote:
> This is probably a really basic question... my ST_Within or ST_Intersects selecting points in a continent are way too slow (both take upward of 200 secs).
>
>        SELECT Count(c_id)
>        FROM c, continents n
>        WHERE ST_Intersects(c.the_geom, n.the_geom) AND
>                n.continent = 'North America';
>
>
> Both tables have gist indexes on the geometries. The above query has the following plan
>
> "Aggregate  (cost=9.66..9.67 rows=1 width=4)"
> "  ->  Nested Loop  (cost=0.00..9.66 rows=1 width=4)"
> "        Join Filter: _st_intersects(c.the_geom, n.the_geom)"
> "        ->  Seq Scan on continents n  (cost=0.00..1.10 rows=1 width=32)"
> "              Filter: ((continent)::text = 'North America'::text)"
> "        ->  Index Scan using pbdb__collections_the_geom on collections c  (cost=0.00..8.30 rows=1 width=104)"
> "              Index Cond: (c.the_geom && n.the_geom)"
>
> The table c has approx 120K rows, and the continents table has 8 rows.Suggestions on how I can improve this? Yes, the computer is otherwise very swift and modern.
>
>
>
> --
> Puneet Kishor
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