Hello,
below a query example generated by mapserver (geographic map application) :
We try here to get data received from a transceiver between 2 dates ( 2
days here)
------------------------------------------------
explain analyse SELECT
mobile_stop_sequence::text,(heading*-1)::text,
asbinary(force_collection(force_2d(geom)),'NDR'),
OID::text from gps_frame_history
WHERE
((gps_date >= '2007-12-03 23:00:00')
AND (gps_date < '2007-12-04 22:59:59')
AND (natural_sbox_id=1208545575)
AND validity::integer>2)
and
(geom
&&
setSRID( 'BOX3D(-7.08254579948851 41.0580019863301,12.4007108828096
51.278592662519)'::BOX3D,find_srid('','gps_frame_history','geom'))
);
Result of EXPLAIN ANALYSE :
---------------------------------
"Index Scan using gist_frame_history_geom on gps_frame_history
(cost=0.00..6.04 rows=1 width=42) (actual time=98423.796..98423.796
rows=0 loops=1)"
" Index Cond: (geom &&
'0103000020E61000000100000005000000BBE6D4E286541CC00632ED9B6C874440BBE6D4E286541CC05C36A3ECA8A3494015A311FA29CD28405C36A3ECA8A3494015A311FA29CD28400632ED9B6C874440BBE6D4E286541CC00632ED9B6C874440'::geometry)"
" Filter: ((gps_date >= '2007-12-03 23:00:00'::timestamp without time
zone) AND (gps_date < '2007-12-04 22:59:59'::timestamp without time
zone) AND (natural_sbox_id = 1208545575) AND ((validity)::integer > 2)
AND (geom &&
'0103000020E61000000100000005000000BBE6D4E286541CC00632ED9B6C874440BBE6D4E286541CC05C36A3ECA8A3494015A311FA29CD28405C36A3ECA8A3494015A311FA29CD28400632ED9B6C874440BBE6D4E286541CC00632ED9B6C874440'::geometry))"
"Total runtime: 98424.337 ms"
table definition :
---------------
CREATE TABLE gps_frame_history
(
natural_sbox_id integer NOT NULL,
gps_date timestamp without time zone NOT NULL,
badge_id character varying(256),
gmt_creation_date timestamp without time zone NOT NULL DEFAULT now(),
speed numeric,
altitude numeric,
heading numeric,
validity character varying(256),
sbox_input integer,
sbox_output integer,
geom geometry,
mobile_stop_sequence integer,
"index" integer DEFAULT
nextval(('public.gps_frame_history_index_seq'::text)::regclass),
CONSTRAINT xpkgps_frame_history PRIMARY KEY (natural_sbox_id, gps_date),
CONSTRAINT enforce_dims_geom CHECK (ndims(geom) = 2),
CONSTRAINT enforce_geotype_geom CHECK (geometrytype(geom) =
'POINT'::text OR geom IS NULL),
CONSTRAINT enforce_srid_geom CHECK (srid(geom) = 4326)
)
WITH OIDS;
-- Index: gist_frame_history_geom
-- DROP INDEX gist_frame_history_geom;
CREATE INDEX gist_frame_history_geom
ON gps_frame_history
USING gist
(geom);
-- Index: idx_frame_history_oid
-- DROP INDEX idx_frame_history_oid;
CREATE UNIQUE INDEX idx_frame_history_oid
ON gps_frame_history
USING btree
(oid);
-- Index: idx_gps_frame_history_id_date
-- DROP INDEX idx_gps_frame_history_id_date;
CREATE INDEX idx_gps_frame_history_id_date
ON gps_frame_history
USING btree
(natural_sbox_id, gps_date);
Olivier
Scott Marlowe a écrit :
On Dec 13, 2007 7:15 AM, olivier boissard <olivier.boissard@xxxxxxxxx> wrote:
A.Burbello a écrit :
Hi people,
I have a case and I got a doubt what should be the
best ways.
One table has more than 150 million of rows, and I
thought that could divided by state.
For each row has person ID, state and other
informations, but the search would be done only by
person ID (number column).
I can improve the query by putting index in that
column, but is there any other ways?
I also studies how to improve performances on big tables.
Like you , I don't know how to improve without index. It's the only way
I found .
I find postgresql is fast on small table but I got real performance
problem when increases the number of rows
Do anyone know if there is specific postgresql tuning parameters in
.conf file for big tables ?
max_fsm_pages ?
max_fsm_relations ?
More often than not, the answer lies not in tuning but in rearranging
how you think of your data and how you create indexes.
If you guys post some schema and queries (with explain analyze) that
aren't running so fast, we'll try to help. although pgsql-perform is
the better place to do that.
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--
Olivier BOISSARD
olivier.boissard@xxxxxxxxx
CERENE SERVICES SA
3, rue Archimède
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Tel : 33 (0)3 25 74 11 78
Fax : 33 (0)3 25 78 39 67
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TIP 9: In versions below 8.0, the planner will ignore your desire to
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