Thread: postgres-fdw questions

Hello,

I'm currently testing postgres_fdw feature on PostgreSQL 9.3.2 and I have some
questions:

  - What are the limits to the number of foreign tables ?
  - What is the current status about foreign joins push-down ?

Thanks in advance,
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2014/1/24 Emmanuel Medernach <medernac@clermont.in2p3.fr>:
> Hello,
>
> I'm currently testing postgres_fdw feature on PostgreSQL 9.3.2 and I have
> some questions:
>
>  - What are the limits to the number of foreign tables ?

As far as I know, there is no limit (beyond the usual PostgreSQL limits).

>  - What is the current status about foreign joins push-down ?

Unless I'm mistaken (and no doubt someone will correct me if I am),
joins cannot be pushed down yet, only WHERE clauses for individual foreign
table rows.

To quote this article about PostgreSQL 9.3: http://lwn.net/Articles/550418/
  'More work needs to be done in this area to make this a full "big data"
  solution, however; Hanada hopes to add "push down" of joins, sorts,
  and aggregates in future versions of PostgreSQL."

See also this thread:

  http://www.postgresql.org/message-id/20131121150515.GC23976@momjian.us

Regards

Ian Barwick

On 24 January 2014 09:20, Emmanuel Medernach <medernac@clermont.in2p3.fr> wrote:
> Hello,
>
> I'm currently testing postgres_fdw feature on PostgreSQL 9.3.2 and I have
> some questions:
>
>  - What are the limits to the number of foreign tables ?

As far as I'm aware, there isn't one.

>  - What is the current status about foreign joins push-down ?

WHERE conditions are pushed down, but I don't think joins or aggregates are.

Thom

On 01/24/2014 04:58 PM, Jim Mlodgenski wrote:
>
>
>
> On Fri, Jan 24, 2014 at 4:20 AM, Emmanuel Medernach <medernac@clermont.in2p3.fr
> <mailto:medernac@clermont.in2p3.fr>> wrote:
>
>     Hello,
>
>     I'm currently testing postgres_fdw feature on PostgreSQL 9.3.2 and I have
>     some questions:
>
>       - What are the limits to the number of foreign tables ?
>       - What is the current status about foreign joins push-down ?
>
>
> The Custom Scan API patch adds the ability to push down joins to foreign tables,
> but its still pending
> https://commitfest.postgresql.org/action/patch_view?id=1282
>

Very interesting, keep up the good work.

Thanks for all your replies.
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