Re: Optimization for updating foreign tables in Postgres FDW

On 2015/03/05 21:08, Etsuro Fujita wrote:
> Here is an updated version.

> The EXPLAIN output has also been improved as discussed in [1].

I noticed that the EXPLAIN for a pushed-down update (delete) on
inheritance childs doubly displays "Foreign Update" ("Foreign Delete"),
one for ForeignScan and the other for ModifyTable. Here is an example:

postgres=# explain verbose update parent set c1 = c1;
QUERY PLAN
------------------------------------------------------------------------------
Update on public.parent (cost=0.00..364.54 rows=4819 width=10)
Update on public.parent
Foreign Update on public.ft1
Foreign Update on public.ft2
-> Seq Scan on public.parent (cost=0.00..0.00 rows=1 width=10)
Output: parent.c1, parent.ctid
-> Foreign Update on public.ft1 (cost=100.00..182.27 rows=2409
width=10)
Remote SQL: UPDATE public.t1 SET c1 = c1
-> Foreign Update on public.ft2 (cost=100.00..182.27 rows=2409
width=10)
Remote SQL: UPDATE public.t2 SET c1 = c1
(10 rows)

Should we do something? Suggestions are welcome.

Best regards,
Etsuro Fujita

[1] http://www.postgresql.org/message-id/31942.1410534785@sss.pgh.pa.us