[postgis-users] ERROR: Out of memory

[Andreas Laggner]

Moin Mark,

the result from the explain:

"Aggregate  (cost=4354.35..4354.36 rows=1 width=32)"
"  ->  Seq Scan on all_lines  (cost=0.00..3826.68 rows=211068 width=32)"

adios      Andreas



Mark Cave-Ayland schrieb:
> On Mon, 2007-10-08 at 10:24 +0200, Andreas Laggner wrote:
>   
>> Hi,
>>
>> i tried to perform the "union approach" from Kevin 
>> http://postgis.refractions.net/support/wiki/index.php?ExamplesOverlayTables
>> the first query worked fine:
>>  CREATE TABLE all_lines AS
>>    SELECT St_ExteriorRing (the_geom) AS the_geom FROM ffhsinglerep
>>    UNION ALL
>>    SELECT St_ExteriorRing (the_geom) AS the_geom FROM spasinglerep;
>>
>> but in the second one i get an error:
>> CREATE TABLE noded_lines AS
>>    SELECT St_Union(the_geom) AS the_geom
>>    FROM all_lines;
>>
>> ERROR: Out of memory
>> SQL Status:53200
>> Detail:Failed on request of size 20750552.
>>
>> If anybody knows what may be behind this error......i have no idea!
>>
>> Cheers      Andreas
>>     
>
> Aggregates shouldn't run out of memory in general; the only time I have
> seen this discussed is if a Hash Aggregate plan is chosen for a large
> number of rows due to incorrect ANALYZE estimates. What does the output
> of "EXPLAIN SELECT St_Union(the_geom) AS the_geom FROM all_lines;" show?
>
>
> ATB,
>
> Mark.
>
>   


-- 
Dipl. Geoökologe Andreas Laggner
Institut für Ländliche Räume (LR)
Bundesforschungsanstalt für Landwirtschaft (FAL)

Institute of Rural Studies
Federal Agricultural Research Centre (FAL)

Bundesallee 50
D-38116 Braunschweig

Tel.: (+49) (0)531 596 5515
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E-mail: andreas.laggner at fal.de
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