[postgis-users] ST_SPHEROID_LENGTH SLOW

[Paul Ramsey]

That's deeply odd, and worth investigating. Can you try 8.3+1.3.3, so
we can eliminate the PostGIS version as a variable first? Then I'll
see if I can duplicate the result on my system.

P.

On Sat, Sep 27, 2008 at 12:59 PM, David Vaz <davidvaz at dcc.fc.up.pt> wrote:
> Hi,
>
> I am a debian user, several months ago debian testing introduced
> postgresql-8.3, and later postgis 1.3 for postgresql-8.3. The problem I
> am facing is that length_spheroid is much slower in postgres-8.3 from
> under 1s to about 60s (See Bellow). I have google-it without any luck.
> Does anyone have any idea on why this happens?
>
> Both databases are equal, tested in same machine, with different
> installations to avoid software versions conflicts.
>
> FIRST:
> postgresql-8.2 (version 8.2.7-2+b1) with postgis (version 1.3.2-1)
>
> EXPLAIN ANALYSE select length_spheroid(geom,'SPHEROID["WGS
> 84",6378137,298.257223563]') FROM test order by id limit 100;
>
> QUERY
> PLAN
> -------------------------------------------------------------------------------------------------------------------------------------------------------
>  Limit  (cost=0.00..17.44 rows=100 width=26054) (actual
> time=1.852..588.394 rows=100 loops=1)
>   ->  Index Scan using test_pkey on test  (cost=0.00..2268.52
> rows=13010 width=26054) (actual time=1.850..588.298 rows=100 loops=1)
>  Total runtime: 588.495 ms
> (3 rows)
>
> SECOND:
> postgresql-8.3 (version 8.3.3-1) with postgis (version 1.3.3-3)
>
> EXPLAIN ANALYSE select length_spheroid(geom,'SPHEROID["WGS
> 84",6378137,298.257223563]') FROM test order by id limit 100;
>
> QUERY
> PLAN
>
> ------------------------------------------------------------------------------------------------------------------------------------------------------------
>  Limit  (cost=0.00..8.74 rows=100 width=104429) (actual
> time=182.734..59741.720 rows=100 loops=1)
>   ->  Index Scan using test_pkey on test  (cost=0.00..1137.11
> rows=13010 width=104429) (actual time=182.732..59741.572 rows=100 loops=1)
>  Total runtime: 59741.897 ms
> (3 rows)
>
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