This is a Debian bug report, which needs upstream attention.
------- Forwarded Message
Date: Thu, 28 Oct 1999 13:45:18 -0400
From: Brian Ristuccia <brianr@osiris.978.org>
To: submit@bugs.debian.org
Subject: Bug#48582: psql spends hours computing results it already knows
Package: postgresql
Version: 6.5.2-3
massive_db=> explain select count(*) from huge_table;
NOTICE: QUERY PLAN:
Aggregate (cost=511.46 rows=9923 width=12) -> Seq Scan on huge_table (cost=511.46 rows=9923 width=12)
EXPLAIN
If huge_table really is huge -- like 9,000,000 rows instead of 9923, after
postgresql already knows the number of rows (that's how it determines the
cost), it proceeds to do a very long and CPU/IO intensive seq scan to
determine the count().
- --
Brian Ristuccia
brianr@osiris.978.org
bristucc@nortelnetworks.com
bristucc@cs.uml.edu
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