Re: postgres_fdw : disable extended queries - Mailing list pgsql-general

From Nicolas Paris
Subject Re: postgres_fdw : disable extended queries
Date
Msg-id CA+ssMOSUQtOcrc1nL46A=Bq1D-vXWXEePpcm+0iDVdei6JK2VQ@mail.gmail.com
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In response to Re: postgres_fdw : disable extended queries  (Albe Laurenz <laurenz.albe@wien.gv.at>)
List pgsql-general


2016-10-24 10:36 GMT+02:00 Albe Laurenz <laurenz.albe@wien.gv.at>:
Nicolas Paris wrote:
> I have a 9.6 pg instance, and I am trying to link a foreign postgresql database that do not accept
> extended queries. (only simple queries https://www.postgresql.org/docs/current/static/protocol.html )
>
> When I run a query against the foreign pg instance thought postres_fdw, it looks like it sends a
> transaction containing
>
> DECLARE c1 CURSOR FOR
> SELECT customer_id FROM foodmart.customer
>
> -> is there a way to run a simple query with postgres_fdw such:
>
> SELECT customer_id FROM foodmart.customer

No, it is part of the design that cursors are used, so that rows can be
fetched one at a time and concurrent DML statements can be run.
 
​Actually problem is not with the cursor, sorry. Error message says it's related to a prepared statement.
I am not able to debug it and see what is happening and what is the prepared statement. ​
 
 
You might consider using dblink.

Dblink works great, but It seems less flexible (no predicate push down). I am able to create a view that encapsulate dblink, but all the rows are fetch each time I use the view.


Yours,
Laurenz Albe

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