postgres-fdw questions

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:

/messages/by-id/20131121150515.GC23976@momjian.us

Regards

Ian Barwick

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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

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On Fri, Jan 24, 2014 at 4:20 AM, 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 ?
- 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

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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