[postgis-users] Strange result about spatial indexes?

[José Carlos Martínez]

Sorry about that..I am using sky drive for storing the file. The 
'download' link from the htmlpage works though.
You can check it out with your own tables too I think you are going to 
find the same problem.


Paul Ramsey escribió:
> That link isn't downloading for me, it's an HTML page instead of a tar file...
>
> On Thu, Aug 13, 2009 at 9:03 PM, Jose Carlos<jomarlla at cgf.upv.es> wrote:
>   
>> Hi,
>> I made the table smaller for sharing. Now the table has just 1600 rows.
>> The effect still remains.  I tried with others tables and other PostGIS
>> versions, I tried even just with tables with POINT features getting similar
>> results.
>>
>> Thanx,
>> Best
>>
>> You can download the table from here:
>> http://cid-40b8dee7bf5b661f.skydrive.live.com/self.aspx/.Public/data.tgz
>>
>> test3=# explain analyze select count(*) from suelos1 s1, suelos1 s2
>> where (s1.geom && s2.geom);
>>                                                                QUERY
>> PLAN
>> -------------------------------------------------------------------------------------------------------------------------------------------
>>  Aggregate  (cost=1095.91..1095.92 rows=1 width=0) (actual
>> time=2840.187..2840.189 rows=1 loops=1)
>>   ->  Nested Loop  (cost=0.00..1079.87 rows=6416 width=0) (actual
>> time=0.111..2820.408 rows=13808 loops=1)
>>         ->  Seq Scan on suelos1 s1  (cost=0.00..130.04 rows=1604
>> width=4597) (actual time=0.009..2.580 rows=1604 loops=1)
>>         ->  Index Scan using suelos1_geom on suelos1 s2
>> (cost=0.00..0.58 rows=1 width=4597) (actual time=0.778..1.729 rows=9
>> loops=1604)
>>               Index Cond: (s1.geom && s2.geom)
>>  Total runtime: 2840.270 ms
>> (6 rows)
>>
>> test3=# explain analyze select count(*) from suelos1 s1, suelos1 s2
>> where (st_expand(s1.geom,00) && s2.geom);
>>                                                                QUERY
>> PLAN
>> -------------------------------------------------------------------------------------------------------------------------------------------
>>  Aggregate  (cost=1087.92..1087.93 rows=1 width=0) (actual
>> time=212.789..212.790 rows=1 loops=1)
>>   ->  Nested Loop  (cost=0.00..1087.89 rows=13 width=0) (actual
>> time=0.090..189.842 rows=13808 loops=1)
>>         ->  Seq Scan on suelos1 s1  (cost=0.00..130.04 rows=1604
>> width=4597) (actual time=0.012..2.632 rows=1604 loops=1)
>>         ->  Index Scan using suelos1_geom on suelos1 s2
>> (cost=0.00..0.58 rows=1 width=4597) (actual time=0.043..0.084 rows=9
>> loops=1604)
>>               Index Cond: (st_expand(s1.geom, 0::double precision) &&
>> s2.geom)
>>  Total runtime: 212.864 ms
>>
>>
>> (6 rows)
>>
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>>
>>     
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