On Thu, Aug 14, 2008 at 17:55, Igor Neyman <ineyman@xxxxxxxxxxxxxx> wrote: > > -----Original Message----- > From: Dmitry Teslenko [mailto:dteslenko@xxxxxxxxx] > Sent: Thursday, August 14, 2008 6:57 AM > To: pgsql-general@xxxxxxxxxxxxxx > Subject: Strange query plan > > Hello! > > I have following table: > > CREATE TABLE table1 ( > field1 INTEGER NOT NULL, > field2 INTEGER NOT NULL, > field3 CHARACTER(30), > ... some more numeric fields) > > I have also those indexes: > > CREATE UNIQUE INDEX idx1 ON table1 USING btree (field3, field2, field1) > CREATE INDEX idx2 ON table1 USING btree (field1, field3) > > Then I query this table with something like this: > > SELECT SUM(...) FROM table1 WHERE field3 = 'ABC' AND field1 <> 1 > GROUP BY field2 > > And planner picks up a sequential scan of a table. Why does he? > > > [I.N.] > How big is your table? > If it's not too big, the cost of table scan might be lower than using > index. > > Igor Table contains ~1 million rows and scan takes very long time. That's the reason I'm asking the question on a mail list. -- A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?
