Re: Use %u to print user mapping's umid and userid

Hi,

On 2016/02/09 14:09, Ashutosh Bapat wrote:
> Sorry, I was wrong. For public user mapping userid is 0 (InvalidOid),
> which is returned as is in UserMapping object. I confused InvalidOid
> with -1.

I think the following umid handling in postgresGetForeignPlan has the
same issue:

     /*
      * Build the fdw_private list that will be available to the executor.
      * Items in the list must match order in enum FdwScanPrivateIndex.
      */
     fdw_private = list_make4(makeString(sql.data),
                              retrieved_attrs,
                              makeInteger(fpinfo->fetch_size),
                              makeInteger(foreignrel->umid));

I don't think it's correct to use makeInteger for the foreignrel's umid.

You store the umid in the fdw_private list here and extract it from the
list in postgresBeginForeignScan, to get the user mapping.  But we
really need that?  We have a validated plan when getting called from
postgresBeginForeignScan, so if foreign join, we can simply pick any of
the plan's fs_relids and use it to identify which user to do the remote
access as, in the same way as for foreign tables.

Attached is a patch for that.

Best regards,
Etsuro Fujita