General Bug Report: Bug in optimizer

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POSTGRESQL BUG REPORT TEMPLATE
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Your name : Andriy I Pilipenko
Your email address : bamby(at)marka(dot)net(dot)ua

Category : runtime: back-end: SQL
Severity : serious

Summary: Bug in optimizer

System Configuration
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Operating System : FreeBSD 2.2.6, FreeBSD 3.1, Linux 2.0.36

PostgreSQL version : 6.4.2

Compiler used : gcc 2.7.2.1

Hardware:
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Pentium, AMD K6, 256M RAM, 64M RAM

Versions of other tools:
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gmake 3.76.1, flex 2.5.4

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Problem Description:
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Backend forgets about indexes if WHERE clause includes
negative number. This causes great slowdown in queries
on large tables.

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Test Case:
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Here is an example session. Note that in first SELECT
backend uses index scan, and in second one it uses
sequental scan.

== cut ==
bamby=> create table table1 (field1 int);
CREATE
bamby=> create index i_table1__field1 on table1 (field1);
CREATE
bamby=> explain select * from table1 where field1 = 1;
NOTICE: QUERY PLAN:

Index Scan using i_table1__field1 on table1 (cost=0.00 size=0 width=4)

EXPLAIN
bamby=> explain select * from table1 where field1 = -1;
NOTICE: QUERY PLAN:

Seq Scan on table1 (cost=0.00 size=0 width=4)

EXPLAIN
== cut ==

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Solution:
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