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

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.