Hi,
I have the following simple query on a simple table:
system=# select * from history where lookup = 'trunk' and lookupid = '248'
order by created desc limit 1000;
system=# \d history
Table "public.history"
Column | Type | Modifiers
----------+--------------------------+------------------------------------------------------
id | integer | not null default
nextval('history_id_seq'::regclass)
created | timestamp with time zone |
creator | integer | not null default 1
contact | integer | not null default 1
type | character varying | not null default ''::character varying
lookup | text |
lookupid | integer | not null default 1
value | text |
Indexes:
"history_pkey" PRIMARY KEY, btree (id)
"history_created_index" btree (created)
"history_creator_index" btree (creator)
"history_lookup_lookupid_creator_index" btree (lookup, lookupid, creator)
"history_lookup_lookupid_index" btree (lookup, lookupid)
Foreign-key constraints:
"history_contact_constraint" FOREIGN KEY (contact) REFERENCES contact(id)
"history_creator_constraint" FOREIGN KEY (creator) REFERENCES contact(id)
system=# explain select * from history where lookup = 'trunk' and lookupid =
'248' order by created desc limit 1000;
QUERY PLAN
-----------------------------------------------------------------------------------------------------------------
Limit (cost=0.00..14799.28 rows=1000 width=58)
-> Index Scan Backward using history_created_index on history
(cost=0.00..12201987.90 rows=824499 width=58)
Filter: ((lookup = 'trunk'::text) AND (lookupid = 248))
(3 rows)
Why doesn't it use the index specified in select? How can I change the query to
make it faster?
Thanks,
Antonio
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