Re: RTE_NAMEDTUPLESTORE, enrtuples and comments

On Mon, Jun 12, 2017 at 12:04 AM, Thomas Munro
<thomas.munro@enterprisedb.com> wrote:
> Here are a couple of ways forward that I can see:
>
> 1.  Figure out how to get the QueryEnvironment through more of these
> stack frames (possibly inside other objects), so that
> set_namedtuplestore_size_estimates can look up enrtuples by enrname:

If you were going to do this, the thing to do would be to get it
hooked up to the PlannerInfo, possibly via an intermediate hop in the
Query.

> 2.  Rip the row estimation out for now, use a bogus hard coded
> estimate like we do in some other cases, and revisit later.  See
> attached (including changes from my previous message).
> Unsurprisingly, a query plan changes.

Perhaps this is a silly question, but I don't particularly see what's
wrong with:

3. Do nothing.

If I understand correctly, for the current use of named tuplestores,
the existing code produces correct estimates.  If we chose option #1,
that would still be true, but we'd have to change a bunch of code to
get there.  If we chose option #2, it would cease to be true.  Why not
just leave it alone?

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company