From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
---|---|
To: | Magnus Hagander <magnus(at)hagander(dot)net> |
Cc: | Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>, Elvis Pranskevichus <elprans(at)gmail(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: [PATCH v1] Add and report the new "in_hot_standby" GUC pseudo-variable. |
Date: | 2017-04-05 16:22:45 |
Message-ID: | CA+TgmoYE7nGHX8DAh+J5TyMnAb80YPW5YZM_5mHznB9HVM0p+A@mail.gmail.com |
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On Thu, Mar 23, 2017 at 4:50 AM, Magnus Hagander <magnus(at)hagander(dot)net> wrote:
> One thing we might want to consider around this -- in 10 we have
> target_session_attrs=read-write (since
> 721f7bd3cbccaf8c07cad2707826b83f84694832), which will issue a SHOW
> transaction_read_only on the connection.
>
> We should probably consider if there is some way we can implement these two
> things the same way. If we're inventing a new variable that gets pushed on
> each connection, perhaps we can use that one and avoid the SHOW command?
I think that would be a good idea. It was, in fact, proposed to do
exactly that as part of the patch that added
target_session_attrs=read-write, but we ended up not doing anything
about it because the SHOW mechanism would still be needed when
connecting to pre-10 versions of PostgreSQL. Therefore, it seemed
like a separate improvement. But if we're adding a GUC_REPORT value
that could be used for the same or a similar purpose, I think it would
make sense to consider revising that mechanism to leverage it as well,
obviously only on releases that have the GUC.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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