Vlad Arkhipov <arhipov@dc.baikal.ru> writes:
> EXPLAIN ANALYZE
> SELECT *
> FROM i
> WHERE d BETWEEN '2007-05-12' AND '2007-05-12'
> Index Scan using i_d on i (cost=0.00..2.39 rows=1 width=402) (actual
> time=0.053..4.284 rows=1721 loops=1)
> Index Cond: ((d >= '2007-05-12'::date) AND (d <= '2007-05-12'::date))
> Total runtime: 6.645 ms
> EXPLAIN ANALYZE
> SELECT *
> FROM i
> WHERE d = '2007-05-12'
> Index Scan using i_d on i (cost=0.00..38.97 rows=1572 width=402)
> (actual time=0.044..4.250 rows=1721 loops=1)
> Index Cond: (d = '2007-05-12'::date)
> Total runtime: 6.619 ms
Hmm, I wonder whether we shouldn't do something like this
http://archives.postgresql.org/pgsql-committers/2008-03/msg00128.php
for all range conditions, not just those made up by
prefix_selectivity().
regards, tom lane