| From: | Peter Geoghegan <pg(at)bowt(dot)ie> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | 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: | 2018-08-24 01:27:54 |
| Message-ID: | CAH2-WzmWSDO3KTMQqMVH6emCz-Y0G7C_WZwLF40pocfj7SBxFw@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, Aug 23, 2018 at 5:20 PM, Peter Geoghegan <pg(at)bowt(dot)ie> wrote:
> This patch adds an enhancement that is an example of a broader class
> of optimizer enhancement primarily aimed at making star-schema queries
> have more efficient plans, by arranging to use several independent
> nested loop joins based on a common pattern. Each nestloop join has
> one particular dimension table on the outer side, and the fact table
> on the inner side.
Correction: I meant that for each join, the outer side is a scan of
some particular fact table index, while the inner side probes some
particular dimension table's primary key, and evaluates the
dimension's qual.
--
Peter Geoghegan
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