Re: Odd behavior in foreign table modification (Was: Re: Optimization for updating foreign tables in Postgres FDW)

On 2016/01/08 14:08, Etsuro Fujita wrote:
> On 2016/01/07 21:50, Etsuro Fujita wrote:
>> On 2016/01/06 20:37, Thom Brown wrote:

>>> I've run into an issue:
>>>
>>> *# UPDATE master_customers SET id = 22 WHERE id = 16 RETURNING
>>> tableoid::regclass;
>>> ERROR:
>>> CONTEXT:  Remote SQL command: UPDATE public.customers SET id = 22
>>> WHERE ((id = 16)) RETURNING NULL

> While working on this, I noticed that the existing postgres_fdw system
> shows similar behavior, so I changed the subject.
>
> IIUC, the reason for that is when the local query specifies "RETURNING
> tableoid::regclass", the FDW has fmstate->has_returning=false while the
> remote query executed at ModifyTable has "RETURNING NULL", as shown in
> the above example; that would cause an abnormal exit in executing the
> remote query in postgresExecForeignUpdate, since that the FDW would get
> PGRES_TUPLES_OK as a result of the query while the FDW would think that
> the right result to get should be PGRES_COMMAND_OK, from the flag
> fmstate->has_returning=false.
>
> Attached is a patch to fix that.

I added this to the next CF.

https://commitfest.postgresql.org/9/483/

Best regards,
Etsuro Fujita