Re: [HACKERS] OR clause status

> Bruce Momjian wrote:
>
> > I have worked with Vadim privately on the remaining OR clause index
> > issues, and I am done. Please start testing, everyone.
> >
>
> Ran a few tests last night. So far, works great for single, non-internal,
> attributes. However, I was not able to get the query to use the table's oid
> index when such an index existed. Did a VACUUM ANALYZE before the query.
> Will be doing some more testing over the next few days.

Try:
test=> explain select * from test where oid = 3::oid or oid = 4::oid;
NOTICE: QUERY PLAN:

Index Scan using i_test2 on test (cost=4.10 size=1 width=4)

Thomas will have to deal with this before 6.4. The auto-casting of type
oid is not working.

>
> Have not tried any mult-part keys. Will this patch handle a small number of
> OR'ed multi-part keys?

This is another item that I think does not work. The code handles AND
and OR separately, making this hard to handle:

key1 = 7 and (key2 = 99 or key2 = 100)

It will use the first part of the key to get key1 = 7, but recognize
that the first part of the key was matches and use the key2 part. I am
going to study the optimizer code for 6.4, so I may be able to get it
working. Not sure yet.

It will certainly use the first part of a multi-part key if the first
key is the one matching the OR clause.

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