[postgis-devel] What's the differencebetweengeom_accum andbuiltinpostgresql array_append

[Obe, Regina]

Is it bad to do this?  This feels like getting kind of close to the metal, but does avoid the sql penalty.

CREATE OR REPLACE FUNCTION st_geom_accum2(geometry[], geometry)
  RETURNS geometry[] AS
'array_push'
  LANGUAGE 'internal' IMMUTABLE;

With the above my timings before and after (windows 8.2 1.3.2 install)

(Before -  using the lwgeom_accum)

--4,938 ms (st_geom_accum aka lwgeom_accum)
SELECT ST_Numgeometries(ST_Collect(the_geom))
FROM towns;


-- 3,609 ms (using st_geom_accum2 - aka array_append)
SELECT ST_Numgeometries(ST_Collect2(the_geom))
FROM towns;

--max 28,904 points, avg 1595.77, numrecs: 351
SELECT Max(ST_NPoints(the_geom)), Avg(ST_NPoints(the_geom)), count(the_geom) as numrecs
FROM
towns

I'm going to test next with large water polys and try to standardize my sets across all boxes, but I guess for that I'll have to be a bit more patient.

Thanks,

Regina

 

 



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