| From: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Shigeru Hanada <shigeru(dot)hanada(at)gmail(dot)com>, Kohei KaiGai <kaigai(at)kaigai(dot)gr(dot)jp>, Robert Haas <robertmhaas(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: WIP: Join push-down for foreign tables |
| Date: | 2012-01-05 10:58:09 |
| Message-ID: | 4F058241.2000606@enterprisedb.com |
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| Lists: | pgsql-hackers |
On 03.12.2011 01:05, Tom Lane wrote:
> Heikki Linnakangas<heikki(dot)linnakangas(at)enterprisedb(dot)com> writes:
>> Hmm, so you're saying that the FDW function needs to be able to return
>> multiple paths for a single joinrel. Fair enough, and that's not
>> specific to remote joins. Even a single-table foreign scan could be
>> implemented differently depending on whether you prefer fast-start or
>> cheapest total.
>
> ... or ordered vs unordered, etc. Yeah, good point, we already got this
> wrong with the PlanForeignScan API. Good thing we didn't promise that
> would be stable.
This discussion withered down here...
I think the advice to Shigeru-san is to work on the API. We didn't reach
a consensus on what exactly it should look like, but at least you need
to be able to return multiple paths for a single joinrel, and should
look at fixing the PlanForeignScan API to allow that too.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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