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pgsql-server/doc/src/sgml/ref create_index.sgml

From: momjian(at)svr1(dot)postgresql(dot)org (Bruce Momjian)
To: pgsql-committers(at)postgresql(dot)org
Subject: pgsql-server/doc/src/sgml/ref create_index.sgml
Date: 2004-04-20 01:00:27
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Lists: pgsql-committers
CVSROOT:	/cvsroot
Module name:	pgsql-server
Changes by:	momjian(at)svr1(dot)postgresql(dot)org	04/04/19 22:00:27

Modified files:
	doc/src/sgml/ref: create_index.sgml 

Log message:
	> >> My question is whether postgres can index null values, and if not, do I
	> >> have to accept a full table scan when locating records.
	> >
	> > It indexes them, but "is null" is not an indexable operator, so you
	> > can't directly solve the above with a 3-column index.  What you can do
	> > instead is use a partial index, for instance
	> >
	> > create index i on CUSTOMER.WCCustOrderStatusLog (WCOrderStatusID)
	> > where Acknowledged is null and Processing is null;
	> That's a very nifty trick and exactly the sort of answer I was after!
	Add CREATE INDEX doc mention of using partial indexes for IS NULL
	indexing;  idea from Tom.

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