Re: [HACKERS] Update comments in nodeModifyTable.c

On 2017/06/07 0:30, Robert Haas wrote:
> On Mon, Jun 5, 2017 at 4:45 AM, Etsuro Fujita
> <fujita.etsuro@lab.ntt.co.jp> wrote:
>> While working on [1], I noticed that the comment in ExecModifyTable:
>>
>>                   * Foreign table updates have a wholerow attribute when the
>>                   * relation has an AFTER ROW trigger.
>>
>> is not 100% correct because a foreign table has a wholerow attrubute when
>> the relation has an AFTER ROW or BEFORE ROW trigger (see
>> rewriteTargetListUD).  So I'd propose s/an AFTER ROW trigger/a row-level
>> trigger/.  Attached is a patch for that.
> 
> That seems better, but looking at rewriteTargetListUD, it seems that
> the actual rule is that this happens when there is a row-level on
> either UPDATE or DELETE.  If there is only a row-level trigger on
> INSERT, then it is not done.  Perhaps we should try to include that
> detail in the comment as well.

Agreed, but I think it's better to add that detail to this comment in 
ExecInitModifyTable:

      * Initialize the junk filter(s) if needed.  INSERT queries need a 
filter
      * if there are any junk attrs in the tlist.  UPDATE and DELETE always
      * need a filter, since there's always a junk 'ctid' or 'wholerow'
      * attribute present --- no need to look first.

I'd also like to propose to update the third sentence in this comment, 
since there isn't necessarily a ctid or wholerow in the UPDATE/DELETE 
tlist when the result relation is a foreign table.

Attached is an updated version of the patch.

Best regards,
Etsuro Fujita

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