[postgis-users] Overlap Queries - speed

rb rburghol at chesapeakebay.net
Tue Oct 4 12:59:21 PDT 2005

If I understand correctly, the command AddBBox helps the index, not
replaces it. Since I had mentioened in my original post that both tables
had GIST indices, this is why you saw no one make that suggestion to me.

As it was, the use of the spatial index was very effective once I
eliminated the intersection command, reducing query time from over an
hour to a little over 2 minutes.

Also, with regards to the AddBBOx, this is implicit in all geom columns
in later versions.


On Tue, 2005-10-04 at 15:25, Brent Wood wrote:
> I've just read this thread with interest, and it has made me curious. I may
> have missed some posts, but have a question.
> The docs I read (section 4.5) discussed how to add a spatial index on geometry
> columns. I had thought this generated a bounding box for use with the &&
> operator to improve spatial query performance.
> The advice given in this thread was to use AddBBox(the_geom), not to create a
> GIST index.
> Is there any real underlying difference in these two approaches, and if so,
> what is it?
> Thanks,
>   Brent Wood
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rburghol at chesapeakebay.net

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