be sure to use correct data types. I suppose psql uses timestamps so
select id from users where modify_date = '2009-01-08' limit 1;
is converted to
select id from users where modify_date = '2009-01-08 00:00:00'::timestamp limit 1;
try
select id from users where modify_date::date = '2009-01-08'::date limit 1;
regards
thomas
Phoenix Kiula schrieb:
Hi. I have a large table that has a modify_date field in it, which is
timestamp without time zone.
I used to be able to do queries like these in 8.2.3 --
select id from users where modify_date = '2009-01-08' limit 1;
select id from users where modify_date > '2009-01-08' limit 1;
Suddenly these are returning:
id
----
(0 rows)
Time: 11.635 ms
I can see through other SQL that there are rows with these dates in
them! My "\d users" shows these two relevant entries about
modify_date:
Table "public.users"
Column | Type |
Modifiers
-----------------------+-----------------------------+------------------------------
modify_date | timestamp without time zone |
....
Indexes:
"new_idx_modify_date" btree (modify_date) WITH (fillfactor=75)
Any ideas why? I ran an explain analyze and this is the output:
******
=# explain analyze select id from users where modify_date =
'2009-01-08' limit 1;
QUERY PLAN
----------------------------------------------------------------------------------------------------------------------------------
Limit (cost=0.00..0.37 rows=1 width=8) (actual time=0.082..0.082
rows=0 loops=1)
-> Index Scan using new_idx_modify_date on users (cost=0.00..4.12
rows=11 width=8) (actual time=0.074..0.074 rows=0 loops=1)
Index Cond: (modify_date = '2009-01-08 00:00:00'::timestamp
without time zone)
Total runtime: 19.484 ms
(4 rows)
Time: 19.940 ms
******
Another weird thing is that a query that has ">" a certain
modify_date, even just yesterday as the date condition, takes a LONG
time and is almost unusable.
Appreciate any pointers.
Thx!
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