Re: Re: [COMMITTERS] pgsql: Only try to push down foreign joins if the user mapping OIDs mat

On 2016/03/14 11:51, Tom Lane wrote:
> Etsuro Fujita <fujita(dot)etsuro(at)lab(dot)ntt(dot)co(dot)jp> writes:
>> On 2016/03/13 4:46, Andres Freund wrote:
>>> ... The difference apears to be the
>>> check that's now in build_simple_rel() - there was nothing hitting the
>>> user mapping code before for file_fdw.

>> Exactly.

>> I'm not sure it's worth complicating the code to keep that behavior, so
>> I'd vote for adding the change notice to 9.6 release notes or something
>> like that in addition to updating file-fdw.sgml.

> Perhaps it would be useful for an FDW to be able to specify that user
> mappings are meaningless to it? And then bypass this check for such FDWs?
>
> I'm not really sold on enforcing that people create meaningless user
> mappings. For one thing, they're likely to be sloppy about it, which
> could lead to latent security problems if the FDW later acquires a
> concept that user mappings mean something.

Seems reasonable.

Best regards,
Etsuro Fujita