Horton

Re: [Proposal] Add foreign-server health checks infrastructure

Kyotaro Horiguchi <horikyota.ntt@gmail.com>

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From: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
To: kuroda.hayato@fujitsu.com
Cc: onderkalaci@gmail.com, andres@anarazel.de, masao.fujii@oss.nttdata.com, pgsql-hackers@lists.postgresql.org, Shinya11.Kato@oss.nttdata.com, zyu@yugabyte.com
Date: 2022-10-17T08:26:42Z
Lists: pgsql-hackers 
At Mon, 17 Oct 2022 07:27:21 +0000, "kuroda.hayato@fujitsu.com" <kuroda.hayato@fujitsu.com> wrote in 
> > In other words, a variation of pgfdw_connection_check_internal()
> > could potentially go into interfaces/libpq/libpq-fe.h
> > (backend/libpq/pqcomm.c or src/interfaces/libpq/fe-connect.c).
> 
> Hmm, IIUC libpq related function and data structures cannot be accessed from core source,
> so we cannot move to pqcomm.c.
> (This is a motivation for introducing libpqwalreceiver library. It is used to avoid to link libpq directly)
> And functions in libpq/fe-connect.c will be included libpq.so,
> but latch related functions like WaitEventSetWait() should not be called from client application.
> So it is also not appropriate.
> In short, there are no good position to place the function because this requires both of libpq and core functions.

Might be on slight different direction, but it looks to me a bit too
much to use WaitEventSet to check only if a socket is live or not.

A quick search in the tree told me that we could use pqSocketCheck()
instead, and I think it would be the something that "could potentially
go into libpq-fe.h" as Önder mentioned, if I understand what he said
correctly.

regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center

Commits

  1. postgres_fdw: Extend postgres_fdw_get_connections to return user name.

  2. postgres_fdw: Fix bug in connection status check.

  3. postgres_fdw: Add connection status check to postgres_fdw_get_connections().

  4. postgres_fdw: Add "used_in_xact" column to postgres_fdw_get_connections().

  5. doc: Enhance documentation for postgres_fdw_get_connections() output columns.

  6. Avoid reference to nonexistent array element in ExecInitAgg().

  7. Add WL_SOCKET_CLOSED for socket shutdown events.

  8. postgres_fdw: reestablish new connection if cached one is detected as broken.