| From: | Antonin Houska <ah(at)cybertec(dot)at> |
|---|---|
| To: | Andy Fan <zhihui(dot)fan1213(at)gmail(dot)com> |
| Cc: | Andrey Lepikhov <a(dot)lepikhov(at)postgrespro(dot)ru>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Suggestions on message transfer among backends |
| Date: | 2019-03-12 08:36:30 |
| Message-ID: | 6236.1552379790@localhost |
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| Lists: | pgsql-hackers |
Andy Fan <zhihui(dot)fan1213(at)gmail(dot)com> wrote:
> I just don't know why shm_mq is designed to single-reader & single-writer.
shm_mq was implemented as a part of infrastructure for parallel query
processing. The leader backend launches multiple parallel workers and sets up
a few queues to communicate with each. One queue is used to send request
(query plan) to the worker, one queue is there to receive data from it, and I
think there's one more queue to receive error messages.
--
Antonin Houska
https://www.cybertec-postgresql.com
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