Very slow queries w/ NOT IN preparation (seems like a bug, test case)

Hi all,

Here is my environment information:

# select version();
                                            version
------------------------------------------------------------------------------------------------
 PostgreSQL 8.3.4 on i686-pc-linux-gnu, compiled by GCC gcc (GCC)
4.2.4 (Ubuntu 4.2.4-1ubuntu3)
(1 row)

I've faced strange parser (or may be planner) behaviour. When I do
"EXPLAIN SELECT 1 FROM table1 WHERE table1_id IN (...~2000 ids
here...);" it works as fast as I expect (50 ms). But when I rewrite it
using NOT IN "EXPLAIN SELECT 1 FROM table1 WHERE table1_id NOT IN
(...~2000 ids here...);" it gets much more slower (34537 ms).

I've done a test case (see attachement) so you can reproduce the
situation (correct PSQL parameter in the begining of the script).

Another thing is that I set my statement_timeout to 20s and it seems
like postgres just ignore this.

Is it a bug and why it happens if not?
Could someone explain what can I do now to make my NOT IN queries work
fast, please?

--
Regards,
Sergey Konoplev
--
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