From: Bruce Momjian on
Markus Wanner wrote:
> Bruce,
>
> Bruce Momjian wrote:
> > Ah, I now realize it only mentions "warm" standby, not "hot", so I just
> > updated the documentation to reflect that; you can see it here:
>
> Maybe the table below also needs an update, because unlike "Warm Standby
> using PITR", a hot standby accepts read-only queries and can be
> configured to not loose data on master failure.

Ahh, good point. I had not considered the table would change. What I
did was to mark "Slaves accept read-only queries" as "Hot only". You
can see the result here:

http://momjian.us/tmp/pgsql/high-availability.html

I did not change "Master failure will never lose data" because the 9.0
streaming implementation is not sychronous (see wal_sender_delay in
postgresql.conf), and I don't think even setting that to zero makes the
operation synchronous. I think we will have to wait for PG 9.1 for
_synchronous_ streaming replication.

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Bruce Momjian <bruce(a)momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ If your life is a hard drive, Christ can be your backup. +

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From: Robert Haas on
On Sun, Feb 7, 2010 at 4:41 AM, Markus Wanner <markus(a)bluegap.ch> wrote:
> Bruce Momjian wrote:
>> Do we want to call the feature "hot standby"?  Is a read-only standby a
>> "standby" or a "slave"?
>
> I think hot standby is pretty much the term, now.

See here for the previous iteration of this discussion:

http://archives.postgresql.org/pgsql-hackers/2009-08/msg00870.php

I've always thought this feature was misnamed and nothing has happened
to change my mind, but it's not clear whether I'm in the majority.

....Robert

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From: "David E. Wheeler" on
On Feb 7, 2010, at 12:35 PM, Josh Berkus wrote:

>> I've always thought this feature was misnamed and nothing has happened
>> to change my mind, but it's not clear whether I'm in the majority.
>
> I'm afraid force of habit is more powerful than correctness on this one.
> It's going to be HS/SR whether that's perfectly correct or not.

What would be correct? I thought HS/SR were pretty correct (as long as no one confuses SR with synchronous replication!).

Best,

David



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From: Fujii Masao on
On Mon, Feb 8, 2010 at 10:34 PM, Bruce Momjian <bruce(a)momjian.us> wrote:
> Ahh, good point.  I had not considered the table would change.  What I
> did was to mark "Slaves accept read-only queries" as "Hot only".

Can the "warm standby" still reside in v9.0? If not, the mark of
"Hot only" seems odd for me.

> I did not change "Master failure will never lose data" because the 9.0
> streaming implementation is not sychronous (see wal_sender_delay in
> postgresql.conf), and I don't think even setting that to zero makes the
> operation synchronous.  I think we will have to wait for PG 9.1 for
> _synchronous_ streaming replication.

You are right.

Regards,

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Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center

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From: Bruce Momjian on
Fujii Masao wrote:
> On Mon, Feb 8, 2010 at 10:34 PM, Bruce Momjian <bruce(a)momjian.us> wrote:
> > Ahh, good point. ?I had not considered the table would change. ?What I
> > did was to mark "Slaves accept read-only queries" as "Hot only".
>
> Can the "warm standby" still reside in v9.0? If not, the mark of
> "Hot only" seems odd for me.

Yes, both hot and warm standby is supported in 9.0.

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EnterpriseDB http://enterprisedb.com

+ If your life is a hard drive, Christ can be your backup. +

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