Jan Kesten wrote:


First, I'm using postgresql 7.4.7 on a 2GHz machine having 1.5GByte RAM
and I have a table with about 220 columns and 20000 rows - and the first
five columns build a primary key (and a unique index).

transfer=> explain analyse SELECT * FROM test WHERE test_a=9091150001
AND test_b=1 AND test_c=2 AND test_d=0 AND test_e=0;

 Index Scan using test_idx on test  (cost=0.00..50.27 rows=1 width=1891)
(actual time=0.161..0.167 rows=1 loops=1)
   Index Cond: (test_a = 9091150001::bigint)
   Filter: ((test_b = 1) AND (test_c = 2) AND (test_d = 0) AND (test_e 0))

This says it's taking less than a millisecond - which is almost certainly too fast to measure accurately anyway. Are you sure this query is the problem?

So, what to do to speed things up? If I understand correctly this
output, the planner uses my index (test_idx is the same as test_pkey
created along with the table), but only for the first column.

1. Are all of test_a/b/c/d/e bigint rather than int?
2. Have you tried explicitly casting your query parameters?
...WHERE test_a=123::bigint AND test_b=456::bigint...

--
  Richard Huxton
  Archonet Ltd

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