Port Bug Report: Strange choice of index, or no choice of index, for numeric keys

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POSTGRESQL BUG REPORT TEMPLATE
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Your name : Philip Warner
Your email address : pjw(at)rhyme(dot)com(dot)au

Category : runtime: back-end: SQL
Severity : non-critical

Summary: Strange choice of index, or no choice of index, for numeric keys

System Configuration
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Operating System : Linux 2.0.35

PostgreSQL version : 6.4

Compiler used : gcc 2.7.2.1

Hardware:
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Pentium, 80MB
Linux Acheron 2.0.35 #8 Wed Aug 19 11:54:15 MEST 1998 i586 unknown

Versions of other tools:
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Problem Description:
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The query optimizer seems to not use indexes for indexes based on float data types, or for range queries based on integers. This seems stramge.

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Test Case:
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Create Table test(f1 float4, f2 int4);
Create Unique Index test_ix1 on test(f1);
Create Unique Index test_ix2 on test(f2);

explain select * from test where f1 = 1.0;
# This does not use an index, this may be OK since it's a float.

explain select * from test where f2 = 1;
#This uses an index, which is good.

explain select * from test where f2 > 1 and f2 < 3;
#This does not use an index, which is strange.

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Solution:
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