Hi all,
I've come to a dead end in trying to get a commonly used query to perform better. The query is against one table with 10 million rows. This table has been analysed. The table definition is:
CREATE TABLE version_crs_coordinate_revision
(
_revision_created integer NOT NULL,
_revision_expired integer,
id integer NOT NULL,
cos_id integer NOT NULL,
nod_id integer NOT NULL,
ort_type_1 character varying(4),
ort_type_2 character varying(4),
ort_type_3 character varying(4),
status character varying(4) NOT NULL,
sdc_status character(1) NOT NULL,
source character varying(4),
value1 numeric(22,12),
value2 numeric(22,12),
value3 numeric(22,12),
wrk_id_created integer,
cor_id integer,
audit_id integer NOT NULL,
CONSTRAINT pkey_version_crs_coordinate_revision PRIMARY KEY (_revision_created, id),
CONSTRAINT version_crs_coordinate_revision_revision_created_fkey FOREIGN KEY (_revision_created)
REFERENCES revision (id) MATCH SIMPLE
ON UPDATE NO ACTION ON DELETE NO ACTION,
CONSTRAINT version_crs_coordinate_revision_revision_expired_fkey FOREIGN KEY (_revision_expired)
REFERENCES revision (id) MATCH SIMPLE
ON UPDATE NO ACTION ON DELETE NO ACTION
)
WITH (
OIDS=FALSE
);
ALTER TABLE "version".version_crs_coordinate_revision ALTER COLUMN _revision_created SET STATISTICS 1000;
ALTER TABLE "version".version_crs_coordinate_revision ALTER COLUMN _revision_expired SET STATISTICS 1000;
ALTER TABLE "version".version_crs_coordinate_revision ALTER COLUMN id SET STATISTICS 1000;
CREATE INDEX idx_crs_coordinate_revision_created ON "version".version_crs_coordinate_revision USING btree (_revision_created);
CREATE INDEX idx_crs_coordinate_revision_created_expired ON "version".version_crs_coordinate_revision USING btree (_revision_created, _revision_expired);
CREATE INDEX idx_crs_coordinate_revision_expired ON "version".version_crs_coordinate_revision USING btree (_revision_expired);
CREATE INDEX idx_crs_coordinate_revision_expired_created ON "version".version_crs_coordinate_revision USING btree (_revision_expired, _revision_created);
CREATE INDEX idx_crs_coordinate_revision_expired_id ON "version".version_crs_coordinate_revision USING btree (_revision_expired, id);
CREATE INDEX idx_crs_coordinate_revision_id ON "version".version_crs_coordinate_revision USING btree (id);
CREATE INDEX idx_crs_coordinate_revision_id_created ON "version".version_crs_coordinate_revision USING btree (id, _revision_created);
The distribution of the data is that all but 120,000 rows have null values in the _revision_expired column.
The query itself that I'm trying to optimise is below:
EXPLAIN
SELECT * FROM (
SELECT
row_number() OVER (PARTITION BY id ORDER BY _revision_created DESC) as row_number,
*
FROM
version_crs_coordinate_revision
WHERE (
(_revision_created <= 16 AND _revision_expired > 16 AND _revision_expired <= 40) OR
(_revision_created > 16 AND _revision_created <= 40)
)
) AS T
WHERE row_number = 1;
Subquery Scan t (cost=170692.25..175678.27 rows=767 width=205)
Filter: (t.row_number = 1)
-> WindowAgg (cost=170692.25..173760.57 rows=153416 width=86)
-> Sort (cost=170692.25..171075.79 rows=153416 width=86)
Sort Key: version_crs_coordinate_revision.id, version_crs_coordinate_revision._revision_created
-> Bitmap Heap Scan on version_crs_coordinate_revision (cost=3319.13..157477.69 rows=153416 width=86)
Recheck Cond: (((_revision_expired > 16) AND (_revision_expired <= 40)) OR ((_revision_created > 16) AND (_revision_created <= 40)))
Filter: (((_revision_created <= 16) AND (_revision_expired > 16) AND (_revision_expired <= 40)) OR ((_revision_created > 16) AND (_revision_created <= 40)))
-> BitmapOr (cost=3319.13..3319.13 rows=154372 width=0)
-> Bitmap Index Scan on idx_crs_coordinate_revision_expired (cost=0.00..2331.76 rows=111041 width=0)
Index Cond: ((_revision_expired > 16) AND (_revision_expired <= 40))
-> Bitmap Index Scan on idx_crs_coordinate_revision_created (cost=0.00..910.66 rows=43331 width=0)
Index Cond: ((_revision_created > 16) AND (_revision_created <= 40))
One thought I have is that maybe the idx_crs_coordinate_revision_expired_created index could be used instead of idx_crs_coordinate_revision_expired.
Does anyone have any suggestions what I could do to improve the plan? Or how I could force the use of the idx_crs_coordinate_revision_expired_created index to see if that is better.
Thanks
Jeremy
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