Re: On-demand running query plans using auto_explain and signals

On 9/18/15 5:05 AM, Shulgin, Oleksandr wrote:
>
> It should not be true - the data sender create DSM and fills it.
> Then set caller slot and send signal to caller. Caller can free DSM
> any time, because data sender send newer touch it.
>
>
> But the requester can timeout on waiting for reply and exit before it
> sees the reply DSM. Actually, I now don't even think a backend can free
> the DSM it has not created. First it will need to attach it,
> effectively increasing the refcount, and upon detach it will only
> decrease the refcount, but not actually release the segment...
>
> So this has to be the responsibility of the reply sending backend in the
> end: to create and release the DSM *at some point*.

What's wrong with just releasing it at the end of the statement? When
the statement is done there's no point to reading it asynchronously anymore.
--
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Experts in Analytics, Data Architecture and PostgreSQL
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