Index selection bug

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                        POSTGRESQL BUG REPORT TEMPLATE
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Your name               : Andriy I Pilipenko
Your email address      : bamby@marka.net.ua


System Configuration
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  Architecture (example: Intel Pentium)         : Intel Pentium

  Operating System (example: Linux 2.0.26 ELF)  : FreeBSD 3.x

  PostgreSQL version (example: PostgreSQL-7.0):   PostgreSQL-7.0.2

  Compiler used (example:  gcc 2.8.0)           : gcc 2.7.2.3


Please enter a FULL description of your problem:
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PostgreSQL refuses to use index if WHERE clause contains function call.
This problem exists in 6.5.3 also.


Please describe a way to repeat the problem.   Please try to provide a
concise reproducible example, if at all possible:
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Do following queries:

    create table t (f int);

    create index i on t (f);

    create function func() returns int as 'select 1' language 'sql';

    set enable_seqscan to 'off';

    explain select * from t where f = 1;

      Index Scan using i on t  (cost=0.00..2.01 rows=1 width=4)

    explain select * from t where f = func();

      Seq Scan on t  (cost=100000000.00..100000001.34 rows=1 width=4)


If you know how this problem might be fixed, list the solution below:
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