We are suddenly getting slow queries on a particular table. Explain shows a sequential scan. We have "vacuum analyze" ed the table.
Any hints?
Many TIA! Mark
testdb=# \d bigtable Table "public.bigtable" Column | Type | Modifiers ---------+---------+----------- id | bigint | not null typeid | integer | not null reposid | integer | not null Indexes: bigtable_id_key unique btree (id) Foreign Key constraints: type FOREIGN KEY (typeid) REFERENCES types(typeid) ON UPDATE NO ACTION ON DELETE NO ACTION, repository FOREIGN KEY (reposid) REFERENCES repositories(reposid) ON UPDATE NO ACTION ON DELETE NO ACTION
testdb=# select count(1) from bigtable; count --------- 3056831 (1 row)
testdb=# explain select * from bigtable where id = 123;
QUERY PLAN
-----------------------------------------------------------
Seq Scan on bigtable (cost=0.00..60000.00 rows=1 width=16)
Filter: (id = 123)
(2 rows)testdb=# vacuum verbose analyze bigtable;
INFO: --Relation public.bigtable--
INFO: Pages 19200: Changed 0, Empty 0; Tup 3056831: Vac 0, Keep 0, UnUsed 207009.
Total CPU 1.03s/0.24u sec elapsed 9.32 sec.
INFO: Analyzing public.bigtable
VACUUM
testdb=# explain select * from bigtable where id = 123;
QUERY PLAN
-----------------------------------------------------------
Seq Scan on bigtable (cost=0.00..57410.39 rows=1 width=16)
Filter: (id = 123)
(2 rows)-- Mark Harrison Pixar Animation Studios
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