Re: Using results from INSERT ... RETURNING

On Oct 4, 2009, at 11:47 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:

> Robert Haas <robertmhaas@gmail.com> writes:
>> Well, I think a patch to implement writeable CTEs is probably going  
>> to
>> have to handle this case - I don't think we can just ignore rewrite
>> rules when processing a CTE.  But it does seem to be beyond the scope
>> of the current patch.
>
> I hadn't been paying too much attention to this thread, but ... why
> is anyone worrying about that?  Rewrite rules are not the concern
> of either the planner or the executor.  A "do also" rule will result
> in two entirely separate Query trees, which will each be planned
> separately and executed separately.  Any given executor run only
> has to think about one type of DML command --- otherwise the executor
> would be broken already, since it takes only one command-type  
> argument.

If an INSERT/UPDATE/DELETE appears within a CTE, it will still need to  
be rewritten. But you're right that this is irrelevant to the present  
patch; I just didn't see that at once.

...Robert