Horton

Re: Sync Rep and shutdown Re: Sync Rep v19

Dimitri Fontaine <dimitri@2ndquadrant.fr>

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From: Dimitri Fontaine <dimitri@2ndQuadrant.fr>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Simon Riggs <simon@2ndquadrant.com>, Fujii Masao <masao.fujii@gmail.com>, Yeb Havinga <yebhavinga@gmail.com>, Jaime Casanova <jaime@2ndquadrant.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2011-03-16T22:23:37Z
Lists: pgsql-hackers

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  1. Document guc context values, and reference them from the config doc section.

Robert Haas <robertmhaas@gmail.com> writes:
> 1. If a die interrupt is received (pg_terminate_backend or fast
> shutdown), then terminate the sync rep wait and arrange for the
> connection to be closed without acknowledging the commit (but do send
> a warning message back).  The commit still happened, though, so other
> transactions will see its effects.  This is unavoidable unless we're
> willing to either ignore attempts to terminate a backend waiting for
> sync rep, or panic the system when it happens, and I don't think
> either of those is appropriate.

Is it possible to force the standby out here, so that logs show that
there was something going on wrt replication?

> 2. If a query cancel interrupt is received (pg_cancel_backend or ^C),
> then cancel the sync rep wait and issue a warning before acknowledging
> the commit.  Again, the alternative is to either ignore the cancel or
> panic, neither of which I believe to be what users will want.

Or force the standby to disconnect.

In both those cases what we have is a situation were either we can't
satisfy the user request or we can't continue to offer sync rep.  You're
saying that we have to satisfy the user's query, so I say kick off sync
rep or it does not make any sense.

> 3. If synchronous_standby_names is changed to '' by editing
> postgresql.conf and issuing pg_ctl reload, then cancel all waits in
> progress and wake everybody up.  As I mentioned before, reloading the

Ok.

Regards,
-- 
Dimitri Fontaine
http://2ndQuadrant.fr     PostgreSQL : Expertise, Formation et Support