[postgis-users] Buffer bug ?

[Mark Cave-Ayland]

> -----Original Message-----
> From: postgis-users-bounces at postgis.refractions.net 
> [mailto:postgis-users-bounces at postgis.refractions.net] On 
> Behalf Of Daniel
> Sent: 26 August 2005 13:13
> To: Mark Cave-Ayland (External)
> Cc: Arnaud Saint Léger; 'PostGIS Users Discussion'
> Subject: Re: [postgis-users] Buffer bug ?
> 
> 
> Hi,
> 
> Thank u very much for your help. Here are precisions u requested:

(cut)

> 6) splitting of the request:
> 
> 6.1) CREATE TABLE temp_lg_annee_bis AS SELECT * FROM 
> lg_annee_bis WHERE lga_annee=2004 and lga_nat_cdn=2 and 
> lga_var > -1; ---> 345 milliseconds
> 
> 6.2) buffer computing: the bug occur


Hi Daniel,

Well it doesn't look as if it's a database tuning problem. Can you try and
isolate the whether it is the buffer() or the collect() which is taking the
time by trying your query without the buffer(), e.g.

	BEGIN;
	CREATE TABLE temp_lg_annee_bis AS SELECT * FROM lg_annee_bis WHERE
lga_annee=2004 and lga_nat_cdn=2 and lga_var > -1;
	SELECT collect(lga_geom) FROM temp_lg_annee_bis GROUP BY lga_annee;
	ABORT;

If it is the buffer() which is causing the slowdown then it's definitely
worth trying upgrading to the latest GEOS release which is now 2.1.4.


Kind regards,

Mark.

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