Counter-intuitively, do this (collecting all your smaller geometries
into one big one to test other features for containment) is probably
going to make your system SLOWER for any given containment query.
As a collection of small objects, the index system can partition out the
few small objects that need to be tested for any given candidate
feature. As a single large object, the same large object will have to be
de-serialized, and every edge of that object tested against the candidate.
Paul
Kevin Neufeld wrote:
Scott Schulthess wrote:
Hello everyone,
I have a table with 60,000 rows.
Each row has a geometry field that is a polygon.
I want to concatenate all of these geometry objects into one big
multipolygon, or at the very least, a polygon, so I can query easily
on one geometry object to see if a point lies within that multipolygon.
...
Use collect(geometry set).
CREATE TABLE my_multi_polygon AS
SELECT collect(geom) AS geom
FROM my_poly_table;
-------------
Kevin Neufeld
Software Developer
Refractions Research Inc.
300-1207 Douglas St.
Victoria, B.C., V8W 2E7
Phone: (250) 383-3022
Email: [EMAIL PROTECTED]
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--
Paul Ramsey
Refractions Research
http://www.refractions.net
[EMAIL PROTECTED]
Phone: 250-383-3022
Cell: 250-885-0632
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