From: | Tatsuo Ishii <ishii(at)sraoss(dot)co(dot)jp> |
---|---|
To: | euler(at)timbira(dot)com(dot)br |
Cc: | michael(at)paquier(dot)xyz, ishii(at)sraoss(dot)co(dot)jp, pgsql-hackers(at)lists(dot)postgresql(dot)org |
Subject: | Re: Adding Unix domain socket path and port to pg_stat_get_wal_senders() |
Date: | 2019-04-14 12:16:41 |
Message-ID: | 20190414.211641.1894238656546034469.t-ishii@sraoss.co.jp |
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Thread: | |
Lists: | pgsql-hackers |
> The question is: what is the problem we want to solve?
The client_hostname is useful for TCP/IP connections because it
indicates which row of the view is related to which standby server. I
would like to have the same for UNIX domain socket case as well.
> Ishii-san asked
> for a socket path. If we have already figured out the replica (via
> application_name), use the replica PID to find the socket path.
Well, I would like to avoid to use application_name if possible.
> A new
> column as suggested by Tom could show the desired info. Is it *really*
> useful? I mean, how many setups have master and replica in the same
> server?
For developing/testing purpose I often create master and some replicas
in the same server. The same technique is used in a regression test
for Pgpool-II.
> For a socket connection, directory is important and that
> information I can get from unix_socket_directories parameter (I've
> never seen a setup with multiple socket directories).
Yes, it could be a way to get the same information that
sockaddr_un.sunpath used to provide. But now I realize that it's not
what I want. What I actually wanted was, which row of the view is
related to which standby server. So what I really need is the standby
server's accepting socket path, *not* primary server's. Currently it
seems it's not possible except using the application_name
hack. Probably cleaner way would be walreciver provides socket path
information in startup packet and walsender keeps the info in shared
memory so that pg_stat_replication view can use it later on.
Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp
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