[postgis-users] add IMMUTALBE to Pg 7.3+ functions
Carl Anderson
carl.anderson at vadose.org
Tue Feb 17 18:37:29 PST 2004
In Postgres 7.3 modifiers where added to function declarations
"IMMUTABLE" indicates to Postgres that the function will always return
the same output given the same input (and does not read other tables)
Can we add this to the declaration of functions for Pg version 7.3+?
That would allow indexing on the geospatial functions.
CREATE FUNCTION x(geometry)
RETURNS float8
AS '@MODULE_FILENAME@','x_point'
LANGUAGE 'C' STRICT IMMUTABLE;
that way in Pg 7.3+ we can
CREATE INDEX my_X_ind on mytab(area2d(the_geom));
versions of Pg prior to 7.3 use WITH (iscachable) which is suppose to
still work in version 7.3 and later but is not in concert with the
underlying SQL spec.
CREATE FUNCTION x(geometry)
RETURNS float8
AS '@MODULE_FILENAME@','x_point'
LANGUAGE 'C' with(isstrict) with(iscachable);
as alway thanks for a great set of tools.
C.
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