Horton

Re: bitmapscan test, no success, again

Pavel Stehule <stehule@kix.fsv.cvut.cz>

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From: Pavel Stehule <stehule@kix.fsv.cvut.cz>
To: pgsql-hackers@postgresql.org
Date: 2005-04-26T12:05:59Z
Lists: pgsql-hackers 
Hello,

I get success, with my hyphotetic sample on big table (100000 rec) Bitmap 
index scan is really usefull.

I tested select count(*) from foo where 
  v IN (11,11,23,11,11,11,11,11,22,71,11)

Some notes.

1. with bitmap index scan 7.16 ms 
2. without bis 165.731 ms (seq. scan) !!!!

3. list of constant contains equals values. Is possible remove it?
  explain analyze select count(*) from foo
    where v in (11,11,11,12)

Regards

Pavel Stehule