On Tue, Mar 12, 2019 at 1:59 PM Andrey Lepikhov <a.lepik...@postgrespro.ru> wrote:
> On 11/03/2019 18:36, Andy Fan wrote: > > Hi: > > I need some function which requires some message exchange among > > different back-ends （connections). > > specially I need a shared hash map and a message queue. > > > > Message queue: it should be many writers, 1 reader. Looks POSIX > > message queue should be OK, but postgre doesn't use it. is there any > > equivalent in PG? > > > > shared hash map: the number of items can be fixed and the value can be > > fixed as well. > > > > any keywords or explanation will be extremely helpful. > You may use shm_mq (shared memory queue) and hash tables (dynahash.c) in > shared memory (see ShmemInitHash() + shmem_startup_hook) > > > > Thanks > > -- > Andrey Lepikhov > Postgres Professional > https://postgrespro.com > The Russian Postgres Company > Thanks Andrey and all people replied this! dynahash/ShmemInitHash is the one I'm using and it is ok for my purposes. I planned to use posix/system v message queue, since they are able to support multi readers/multi writer. I just don't know why shm_mq is designed to single-reader & single-writer.
