On 11/01/2016 08:32 PM, Robert Haas wrote:
On Tue, Nov 1, 2016 at 10:58 AM, Tomas Vondra
<tomas.von...@2ndquadrant.com> wrote:
Damn! You're right of course. Who'd guess I need more coffee this early?

Attached is a fix replacing the flag with an array of flags, indexed by
ParallelMasterBackendId. Hopefully that makes it work with multiple
concurrent parallel queries ... still, I'm not sure this is the right

I feel like it isn't.  I feel like this ought to go in the DSM for
that parallel query, not the main shared memory segment, but I'm not
sure how to accomplish that offhand.  Also, if we do solve it this
way, surely we don't need the locking.  The flag's only set before any
workers have started and never changes thereafter.

I'm not sure what you mean by "DSM for that parallel query" - I thought the segments are created for Gather nodes, no? Or is there a DSM for the whole query that we could use?

Another thing is that maybe we don't really want to give extensions access to any of those segments - my impression was those segments are considered internal (is there RequestAddinShmemSpace for them?). And hacking something just for auto_explain seems a big ugly.


Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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