[DOCS] Online Backups: Minor Caveat, Major Addition?

2006-03-20 Thread Thomas F. O'Connell
I just completed my first online backup and recovery cycle in a test  
environment.


I encountered a minor hiccup at step 8 of the process outlined in the  
docs in 23.3.3, "Recovering with an On-line Backup":


http://www.postgresql.org/docs/8.1/static/backup-online.html#BACKUP- 
PITR-RECOVERY


A base backup taken from a running postmaster will still include a  
postmaster.pid file, which will prevent a new postmaster from being  
able to be started.


As a quick fix, a note could be added to item 4 of the recovery  
process that reads something like the following:


Note: If you are recovering to a new cluster and your base backup was  
taken from a running postmaster, you will need to remove  
postmaster.pid if it exists in order to start the new postmaster.


In reviewing this section of the documentation, though, I'm wondering  
if it might not be more clearly broken into 3 further subsections. I  
would suggest:


23.3.3.1 - Inline (or In-place) Recovery
23.3.3.2 - Remote Recovery or Recovery into a New Cluster
23.3.3.3 - Continuous Recovery

The "Inline Recovery" section would just be the existing 23.3.3  
repurposed.


The "Remote/New Cluster Recovery" section would be an edited version  
of the existing 23.3.3 to eliminate step1 and include the note  
suggested above.


The "Continuous Recovery" section would include details of how to  
continuously apply WAL files to a separate cluster in order to have a  
true hot standby system.


Thoughts?

I'd be happy to draft 23.3.3.2. I'll have to figure out how to  
implement Simon Riggs's suggestion of a wait-for-files  
recover_command including a way to interrupt in the event of a need  
for actual failover-style recovery before I could draft 23.3.3.3,  
though.


--
Thomas F. O'Connell
Database Architecture and Programming
Co-Founder
Sitening, LLC

http://www.sitening.com/
3004 B Poston Avenue
Nashville, TN 37203-1314
615-260-0005 (cell)
615-469-5150 (office)
615-469-5151 (fax)


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Re: [DOCS] Online Backups: Minor Caveat, Major Addition?

2006-03-20 Thread Tom Lane
"Thomas F. O'Connell" <[EMAIL PROTECTED]> writes:
> A base backup taken from a running postmaster will still include a  
> postmaster.pid file, which will prevent a new postmaster from being  
> able to be started.

Usually not; only if the PID mentioned in the file belongs to an
existing process belonging to the postgres userid does Postgres believe
that the pidfile is valid.

It might be worth mentioning this as you suggest, but I think it's a
sufficiently low-probability case that your failure was probably due to
something else.

regards, tom lane

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Re: [DOCS] Online Backups: Minor Caveat, Major Addition?

2006-03-20 Thread Thomas F. O'Connell


On Mar 20, 2006, at 4:48 PM, Tom Lane wrote:


"Thomas F. O'Connell" <[EMAIL PROTECTED]> writes:

A base backup taken from a running postmaster will still include a
postmaster.pid file, which will prevent a new postmaster from being
able to be started.


Usually not; only if the PID mentioned in the file belongs to an
existing process belonging to the postgres userid does Postgres  
believe

that the pidfile is valid.

It might be worth mentioning this as you suggest, but I think it's a
sufficiently low-probability case that your failure was probably  
due to

something else.


My test scenario involved setting up a new cluster on the same  
machine as the base postgres I was attempting to recover. So you're  
probably right about the rarity.


What about the larger suggested change of breaking that section into  
three more granular subsections? I could see commentary being  
slightly more helpful for each.


--
Thomas F. O'Connell
Database Architecture and Programming
Co-Founder
Sitening, LLC

http://www.sitening.com/
3004 B Poston Avenue
Nashville, TN 37203-1314
615-260-0005 (cell)
615-469-5150 (office)
615-469-5151 (fax)

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Re: [DOCS] Online Backups: Minor Caveat, Major Addition?

2006-03-20 Thread Tom Lane
"Thomas F. O'Connell" <[EMAIL PROTECTED]> writes:
> What about the larger suggested change of breaking that section into  
> three more granular subsections? I could see commentary being  
> slightly more helpful for each.

No particular opinion from here.

Someone (was it Scott Marlowe?)  recently volunteered to draft a
complete restructuring of the admin docs --- so it would probably be
better to think about this as part of that effort rather than a
standalone change.

regards, tom lane

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Re: [DOCS] Online Backups: Minor Caveat, Major Addition?

2006-03-20 Thread Scott Marlowe
On Mon, 2006-03-20 at 17:12, Tom Lane wrote:
> "Thomas F. O'Connell" <[EMAIL PROTECTED]> writes:
> > What about the larger suggested change of breaking that section into  
> > three more granular subsections? I could see commentary being  
> > slightly more helpful for each.
> 
> No particular opinion from here.
> 
> Someone (was it Scott Marlowe?)  recently volunteered to draft a
> complete restructuring of the admin docs --- so it would probably be
> better to think about this as part of that effort rather than a
> standalone change.

That was me, and I'm working on it right now, in the background.

If anyone has any input, I'd be glad to hear it.  I'm still getting
docbooks setup on my laptop and such...

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