Re: "Hot standby"?

Mark Mielke wrote:
> To further confuse things, the "temperature" might apply to only a
> particular aspect of the solution. For example, "hot swappable disk
> drives" are drives that probably do sit on a shelf until they are
> needed, and the "hot" aspect only implies that the server does not need
> to be shut down to install the drives, and initialize them for service. :-)
>
> For databases, people seem to be associating "hot" with the ability to
> issue read only queries. As somebody else said - under a definition of
> hot that includes read-only clones, pg_dump/pg_restore could be
> considered a "hot standby" strategy.
>
> I don't agree with that definition. For the clone to be able to perform
> read-only queries does not imply "hot" nor does it imply "standby". It
> implies "slave". The original poster correctly raised this concern.

Agreed. I think by definition, "standby" is "standing by", meaning it
isn't doing anything, so I don't see how a read-only system could be a
standby. I agree "slave" is a better name.

I understand that Oracle uses the terms differently but I assume their
terms were chosen for historical/marketing reasons, and I am not sure
following Oracle is a good idea if their terms are confusing for
non-Oracle folks.

This reminds me of the terminology change we made when we added
point-in-time recovery. At some point we started documenting the
process of "continuous archiving" separately from the process of
"point-in-time recovery". I think that served us well because once
pg_standby was available, we had the possibility of continuous-archiving
happening without the possibility for point-in-time recovery because the
standby was always current.

"Continuous archive slave" might be the most accurate terminology; that
seems the clearest, and people won't have to ask "what is that, exactly".

The streaming WAL log feature should probably be called "streaming
continuous archiving". That does allow the possibility of having a
"streaming continuous archving slave".

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

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