Re: Summary and Plan for Hot Standby

From: Tatsuo Ishii <ishii(at)postgresql(dot)org>
To: simon(at)2ndquadrant(dot)com
Cc: pgsql-hackers(at)postgresql(dot)org, heikki(dot)linnakangas(at)enterprisedb(dot)com
Subject: Re: Summary and Plan for Hot Standby
Date: 2009-11-16 10:06:27
Message-ID: 20091116.190627.108810018.t-ishii@sraoss.co.jp
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> > - Does Hot Standby allow to use prepared query (not prepared
> > transaction) in standby? I mean: Parse message from frontend can be
> > accepted by standby?
>
> Yes, no problem with any of those kind of facilities

Please correct me if I'm wrong. Parse will result in obtaining
RowExclusiveLock on the target table if it is parsing
INSERT/UPDATE/DELETE. If so, is this ok in the standby?

> > - Can we create tempory tables in standby?
>
> No, but this is for two reasons
>
> * CREATE TEMPORARY TABLE actually writes to catalog tables. It doesn't
> need to do that, so allowing this would require some medium-heavy
> lifting of the way temp tables work. A preliminary design was agreed in
> July 2008. I believe it would be a popular feature, since about 40-50%
> of people ask for this.
>
> * CREATE TEMP TABLE is currently considered to be disallowed during read
> only transactions. That might be able to change if the underlying
> physical operation were write-free.

Thanks for explanation.
--
Tatsuo Ishii
SRA OSS, Inc. Japan

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