<p>Bitmapped indexes are good for weakly constrained queries. Else B+tree indexes are better any day. <p>Also I guess
bitmappedindexes work better when there is an OR predicate on different columns in a query. <p> <b><i>Bruce Momjian
</i></b>wrote:<blockquote style="BORDER-LEFT: #1010ff 2px solid; MARGIN-LEFT: 5px; PADDING-LEFT: 5px"><br />See the
emailabout bitmapped indexes linked to from the TODO list item<br />on bitmaps. Bitmap indexes allow arbitrary indexes
tobe combined into<br />a single index. Btree indexes can not be combined.<br /><br
/>---------------------------------------------------------------------------<br/><br />Rajesh Kumar Mallah. wrote:<br
/>>Hi,<br />> <br />> I have learnt from certain texts that bitmap indexes are very useful for<br />> large
DSS(decesion support systems).<br />> <br />> bitmap indexes are currently not available in postgresql.<br />>
<br/>> My question is in what way is a normal btree index in pgsql<br />> inferior to bitmap indexes (found in
oraclefor example).<br />> <br />> is it just in terms of space requirements for performance too?<br />> <br
/>><br />> regds<br />> mallah.<br />> <br />> <br />> -- <br />> Rajesh Kumar Mallah,<br />>
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