Thomas Sailer wrote:
>
> The following query is very quick, it returns 20 rows within a small fraction
> of a second:
> select * from mapelements_rtree where NELAT>=79000000 and SWLAT<=80000000 and
> NELON>=79000000 and SWLON<=80000000;
>
> The following query, however, takes a long time (almost half a minute):
> select * from mapelements,mapelements_rtree where
> mapelements_rtree.NELAT>=79000000 and mapelements_rtree.SWLAT<=80000000 and
> mapelements_rtree.NELON>=79000000 and mapelements_rtree.SWLON<=80000000 and
> mapelements.ID=mapelements_rtree.ID;
>
> This is basically how the rtree documentation suggests to perform
> selects. Why is this query so slow, and what can I do to fix/workaround
> this?
>
Does this query run faster?
select * from mapelements
where ID in
(
select ID from mapelements_rtree
where mapelements_rtree.NELAT>=79000000
and mapelements_rtree.SWLAT<=80000000
and mapelements_rtree.NELON>=79000000
and mapelements_rtree.SWLON<=80000000
);
Dennis Cote
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