Re: PATCH: enabling parallel execution for cursors explicitly (experimental)

On Sat, Oct 14, 2017 at 11:44 PM, Tomas Vondra
<tomas(dot)vondra(at)2ndquadrant(dot)com> wrote:
> Hi,
>
>
> I propose is to add a new cursor option (PARALLEL), which would allow
> parallel plans for that particular user-defined cursor. Attached is an
> experimental patch doing this (I'm sure there are some loose ends).
>

How will this work for backward scans?

>
> Regarding (2), if the user suspends the cursor for a long time, bummer.
> The parallel workers will remain assigned, doing nothing. I don't have
> any idea how to get around that, but I don't see how we could do better.
>

One idea could be that whenever someone uses Parallel option, we can
fetch and store all the data locally before returning control to the
user (something like WITH HOLD option).

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com