Re: BUG #8404: JDBC block hot standby replication?

From: Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>
To: Valentine Gogichashvili <valgog(at)gmail(dot)com>
Cc: pchan(at)contigo(dot)com, PostgreSQL Bugs <pgsql-bugs(at)postgresql(dot)org>
Subject: Re: BUG #8404: JDBC block hot standby replication?
Date: 2013-08-28 12:32:18
Message-ID: 521DEDD2.7010405@vmware.com
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On 28.08.2013 12:46, Valentine Gogichashvili wrote:
> Hello
>
> This is a well documented feature of Hot-Standby Replication.
>
> see:
> http://www.postgresql.org/docs/9.2/static/runtime-config-replication.html#RUNTIME-CONFIG-REPLICATION-STANDBY

That explains how streaming delay and query cancellations work, but the
OP's question was why running the same statements over JDBC behaves
differently than running them over psql.

I'm afraid I don't know the answer. One guess is that when you make the
JDBC connection, you have asked for repeatable read or serializable
isolation level, while psql runs in read committed mode. Running a "show
transaction_isolation" in both would show if that's the case. I'd also
suggest doing "select * from pg_stat_activity" to see if the session
looks the same in both cases.

- Heikki

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