| From: | Peter Geoghegan <pg(at)bowt(dot)ie> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Jim Nasby <jim(dot)nasby(at)openscg(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: [HACKERS] Re: Improve OR conditions on joined columns (common star schema problem) |
| Date: | 2018-02-24 21:00:32 |
| Message-ID: | CAH2-Wz=QkWBHG8dvY-phFChDB0uYav8X8qqp2K8FcTpovX42Pg@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Fri, Feb 2, 2018 at 4:53 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)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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