# [postgis-users] Multipolygons to Polygons

Obe, Regina robe.dnd at cityofboston.gov
Tue Mar 27 05:29:38 PDT 2007

```SELECT geometryn(ogc_geom, generate_series(1, numgeometries(ogc_geom))
As poli
FROM test_table

If you need to use this in a viewer that requires a primary key and
entry into geometry_columns table or your table is fairly large, then
you'll need to create a table with something like

CREATE TABLE test_table2(gid serial, CONSTRAINT pk_test_table2 PRIMARY
KEY(gid));
2);

INSERT INTO test_table2(poli)
SELECT geometryn(ogc_geom, generate_series(1, numgeometries(ogc_geom))
As poli
FROM test_table;

CREATE INDEX idx_test_table2_poli  ON test_table2  USING gist
(poli);

Hope that helps,
Regina

________________________________

From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of
Leticia
Sent: Monday, March 26, 2007 7:17 PM
To: postgis-devel at postgis.refractions.net
Cc: postgis-users at postgis.refractions.net
Subject: [postgis-users] Multipolygons to Polygons
Importance: High

Can I separate the polygons that conform a multipolygon from SQL?

For example, If I query

SELECT AsText(ogc_geom) as poli from test_table

I get:
MULTIPOLYGON(((580525.37 141603.2,580523.3 141629.81,580539.66
141631.09,580540.93 141619.38,580541.46 141608.63,580541.48
141604.73,580525.37 141603.2),(580527.79 141607.36,580532.68
141607.38,580532.61 141622.27,580527.73 141622.26,580527.79 141607.36)))

which consists of 2 polygons....

Can I run a SQL that let me obtain the two separate polygons?

Leticia

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