Re: Fetch zero result rows when executing a query?

On 2015-02-04 12:25:04 +0100, Marko Tiikkaja wrote:
> On 2/4/15 12:17 PM, Stephen R. van den Berg wrote:
> >Andres Freund wrote:
> >>On 2015-02-03 12:26:33 +0100, Shay Rojansky wrote:
> >>>find a way to execute a query but without fetching any rows. The Execute
> >>>message has a maximum result-row count, but zero is documented to mean
> >>>"fetch all rows".
> >
> >>Is this really a relevant optimization? If the user doesn't want
> >
> >I believe he's talking about the network protocol of postgreSQL, not
> >about query optimisation (as you do).
>
> I don't believe so.

Did you read the original post?

> I'm working on the Npgsql, the .NET driver for PostgreSQL, and am trying to
> find a way to execute a query but without fetching any rows. The Execute
> message has a maximum result-row count, but zero is documented to mean
> "fetch all rows".

That's pretty unambiguously about a driver and the network protocol.

> If this is not about optimization, why can't the driver just ignore
> the rows from the server?

IIUC Shay wants to avoid the network traffic incurred by that. I think
that's premature, but it's certainly not completely bogus.

Greetings,

Andres Freund