Tom Lane wrote:
> "Peter Haworth" <pmh@edison.ioppublishing.com> writes:
> > ... why couldn't an explicit IS NULL test
> > be allowed to use the index?
>
> It could, if someone cared to puzzle out a way to integrate IS NULL into
> the index opclass and access method API infrastructure. Right now all
> that stuff assumes that indexable operators are, well, operators (and I
> think there are places that assume they must be binary operators, to
> boot).
>
> I've looked at this once or twice but always decided that the
> bang-for-the-buck ratio was too low compared to other open problems ...
I know we index NULL values in multi-column indexes, but do we
currently even store the rows that have only NULLs in a the index.
--
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