Re: "Hot standby"?

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Greg Stark <gsstark(at)mit(dot)edu>
Cc: Josh Berkus <josh(at)agliodbs(dot)com>, Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, Mark Mielke <mark(at)mark(dot)mielke(dot)cc>, Peter Eisentraut <peter_e(at)gmx(dot)net>, Bruce Momjian <bruce(at)momjian(dot)us>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: "Hot standby"?
Date: 2009-08-12 03:19:18
Message-ID: 603c8f070908112019t7f62f170m6ed48bc651baae9d@mail.gmail.com
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On Tue, Aug 11, 2009 at 9:44 PM, Greg Stark<gsstark(at)mit(dot)edu> wrote:
> On Tue, Aug 11, 2009 at 10:13 PM, Robert Haas<robertmhaas(at)gmail(dot)com> wrote:
>> On Tue, Aug 11, 2009 at 4:07 PM, Josh Berkus<josh(at)agliodbs(dot)com> wrote:
>>> So really, the "streaming replication" patch should be called "hot
>>> standby",
>>
>> No.  AIUI, hot standby means that when your primary falls over, the
>> secondary automatically promotes itself and takes over.
>
> No! This is *not* what "hot standby" means, at least not in the Oracle world.

I'm perplexed by this. For example: http://en.wikipedia.org/wiki/Hot_standby

Admittedly, wikipedia is not an authoritative source, but I've always
understood cold/warm/hot just as Peter described them upthread. Cold
means it's on the shelf. Warm means it's plugged in, but you have to
have to do something to get it going. Hot means it just takes over
when needed.

But of course I guess Oracle can call their features what they want to...

> "log based replication", "read-only slaves", and "hot standby" are all
> 100% accurate descriptions of what the hot standby patch enables. I do
> like "read only slaves" because it's the most precise and meaningful.

Me too.

...Robert

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