Thread: pgsql-server/doc/src/sgml/ref create_index.sgml
pgsql-server/doc/src/sgml/ref create_index.sgml
From
momjian@svr1.postgresql.org (Bruce Momjian)
Date:
CVSROOT: /cvsroot Module name: pgsql-server Changes by: momjian@svr1.postgresql.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.