From: Jerry Sievers <gsievers19@comcast.net>
To: "S. Bob" <sbob@quadratum-braccas.com>
Cc: pgsql-admin@lists.postgresql.org
Subject: Re: xmin value from pg_stat_replication
References: <2bbb14f7-b894-cf98-986f-59e4711d0aa5@quadratum-braccas.com>
Date: Wed, 17 Jul 2019 13:38:08 -0500
In-Reply-To: <2bbb14f7-b894-cf98-986f-59e4711d0aa5@quadratum-braccas.com>
	(S. Bob's message of "Wed, 17 Jul 2019 12:31:29 -0600")
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"S. Bob" <sbob@quadratum-braccas.com> writes:

> All;
>
>
> We have a master and a standby (Streaming replication).
>
> This query produces a value of approx 1.5million on the master and
> approx 80million on the standby:
>
>
> select slot_name, slot_type, database, xmin from pg_replication_slots
> order by age(xmin);

Why does your standby have rep slots?  Is it also feeding lower
subordinate standbys?

>
>
> We are running replication in async mode.
>
>
> A couple of questions:
>
>
> - Is it unusual for the master & standby to differ dramatically like this?
>
> - could the replication slot (i.e. the xmin on the standby) be
> preventing vacuum from cleaning up row versions on the master?
>
>
> Thanks in advance
>
>
>
>
>
>
>
>
>

-- 
Jerry Sievers
Postgres DBA/Development Consulting
e: postgres.consulting@comcast.net