Re: [HACKERS] Re: Improve OR conditions on joined columns (commonstar schema problem) - Mailing list pgsql-hackers

From Peter Geoghegan
Subject Re: [HACKERS] Re: Improve OR conditions on joined columns (commonstar schema problem)
Date
Msg-id CAH2-Wz=QkWBHG8dvY-phFChDB0uYav8X8qqp2K8FcTpovX42Pg@mail.gmail.com
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In response to Re: [HACKERS] Re: Improve OR conditions on joined columns (common star schema problem)  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
On Fri, Feb 2, 2018 at 4:53 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Tomas Vondra <tomas.vondra@2ndquadrant.com> writes:
>> BTW wouldn't it be possible to derive "traditional" proof in relational
>> algebra, similarly to other transforms?
>
> Perhaps.  The patch depends on CTID, but you could probably model that
> as a primary key in a proof.

I'll remind you that commit b648b703 made the TID sort performed by
CREATE INDEX CONCURRENTLY over 3 times faster in cases where the sort
completes in memory. The simplest way to get a significant portion of
that benefit for your approach with sort+unique on CTID would be to
add sortsupport with abbreviated keys to the TID btree opclass.

-- 
Peter Geoghegan


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