[postgis-users] Buffer bug ?

Daniel daniel.faivre at camptocamp.com
Fri Aug 26 07:26:29 PDT 2005


The bug occurs with geos 2.1.4 too ...


Daniel wrote:

> As said in my last post, the problem come from the buffer() function.
> (the collect() only take 345 ms)
>
> I will try a geos update this afternoon and post the result here.
>
> Sincerely yours,
>
> dF
>
> Mark Cave-Ayland wrote:
>
>>> -----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.
>>
>> ------------------------
>> WebBased Ltd
>> 17 Research Way
>> Tamar Science Park
>> Plymouth
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>> T: +44 (0)1752 797131
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>>
>>
>>  
>>
>
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>  
>

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