Re: [POC] Faster processing at Gather node

Hi Rafia,

I like the idea of reducing locking overhead by sending tuples in bulk.
The implementation could probably be simpler: you could extend the API
of shm_mq to decouple notifying the sender from actually putting data
into the queue (i.e., make shm_mq_notify_receiver public and make a
variant of shm_mq_sendv that doesn't send the notification). From Amit's
letter I understand that you have already tried something along these
lines and the performance wasn't good. What was the bottleneck then? If
it's the locking around mq_bytes_read/written, it can be rewritten with
atomics. I think it would be great to try this approach because it
doesn't add much code, doesn't add any additional copying and improves
shm_mq performance in general.

--
Alexander Kuzmenkov
Postgres Professional:http://www.postgrespro.com
The Russian Postgres Company