[postgis-users] long time for finding objects

[Paul Ramsey]

Well, the second or third time you run your slow query, I'd hope it
would be fast, if only because everything is getting pulled into cache
by then. In general, you are doing 81 large object operations, since
your binaries are well over the page size.

3 seconds does sound slow for pulling 81 of anything, although if
you're testing with a terminal or a client, a good deal of the time
could be writing the output into the UI, rather than the actual fetch.
Wrapping the large objects in functions that summarize them will give
you a better feel for the true speed (e.g., instead of pulling geom,
pull st_area(geom), instead of pulling bytea, pull length(bytea).

P

On Wed, Apr 29, 2009 at 7:32 AM, Malm Paul <paul.malm at saabgroup.com> wrote:
> Hi I find it slow to select objects in the PostgreSQL/PostGIS db
> I'm using windows XP, postgreSQL 8.3.7
>
> I have a table "map" with the columns:
> mapid: small int
> scale: small int
> rectangle: geometry
> binary_field: bytea
>
> The database concist of 81 "map" rows, where the binary has a avarage size
> of 80kb.
>
> "SELECT * FROM map" takes about 3 seconds, while
> "SELECT mapid, scale from map" takes about 14 milliseconds
>
> Total size = 80 x 81k = 6,3 mb ( I don' t know, perhaps 3 sec isn' t slow )
>
> Is there a way to speed this up?
> I've tried to increase shared_buffers, and effective_cash_size.
>
> Kind regards,
> Paul
>
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