Re: Best way to scan on-disk bitmaps

Victor Yegorov <viy@mits.lv>

From: "Victor Y. Yegorov" <viy@mits.lv>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Postgres Hackers <pgsql-hackers@postgresql.org>
Date: 2005-05-12T21:27:01Z
Lists: pgsql-hackers
* Tom Lane <tgl@sss.pgh.pa.us> [12.05.2005 23:09]:
> 1. Be sure that all the indexable WHERE conditions are passed to the
>    indexscan as indexquals.  This might be, say,
> 	WHERE a = 42 and b = 'foo'

If I have on-disk bitmap
	ON (a, b, c)
will the planner pick an index scan for
	WHERE a = 42 AND b = 'foo'
(i.e. only part of the index attributes are involved)? Any modifications
needed to achieve this functionality?

To my mind, bitmap scan even for 1 attribute of a multi-column index would be
a win, though I haven't tested this yet.


-- 

Victor Y. Yegorov