On Tue, 17 Feb 2009, Havasvölgyi Ottó wrote:
I created a big enough table (131072 records, and it had also a 3rd
field with about 120 character text data). But Postgres performs a
SeqScan.
Firstly, you should always post EXPLAIN ANALYSE results when asking about
a planning problem.
Secondly, you can't "get" Postgres to choose a particular plan (without
disruptive fiddling with the planner). Postgres will try to choose the
plan that answers the query fastest, and this may be a sequential scan.
What happens if you use the following WHERE clause?
WHERE id1 > 12 AND id1 < 56
Does Postgres use a sequential scan then?
How many rows does your query return? If it's more than about 10% of the
total rows in the table, then a sequential scan is probably the fastest
method.
Matthew
--
Matthew: That's one of things about Cambridge - all the roads keep changing
names as you walk along them, like Hills Road in particular.
Sagar: Yes, Sidney Street is a bit like that too.
Matthew: Sidney Street *is* Hills Road.
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