Re: Problem with PITR recovery - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: Problem with PITR recovery
Date
Msg-id 200504171338.j3HDcEE23341@candle.pha.pa.us
Whole thread Raw
In response to Re: Problem with PITR recovery  (Ragnar Hafstað <gnari@simnet.is>)
Responses Re: Problem with PITR recovery  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Ragnar Hafsta� wrote:
> On Sat, 2005-04-16 at 23:06 -0400, Bruce Momjian wrote:
> [about backup procedure with PITR documentation
> 
> > I see in the docs:
> > 
> >     To make use of this backup, you will need to keep around all the WAL
> >     segment files generated at or after the starting time of the backup. To
> >     aid you in doing this, the pg_stop_backup function creates a backup
> >     history file that is immediately stored into the WAL archive area. This
> >     file is named after the first WAL segment file that you need to have to
> >     make use of the backup. For example, if the starting WAL file is
> >     0000000100001234000055CD the backup history file will be named something
> >     like 0000000100001234000055CD.007C9330.backup. (The second part of this
> >     file name stands for an exact position within the WAL file, and can
> >     ordinarily be ignored.) Once you have safely archived the backup dump
> >     file, you can delete all archived WAL segments with names numerically
> >     preceding this one.
> > 
> > I am not clear on what the "backup dump file" is?  I assume it means
> > 0000000100001234000055CD.  It is called "WAL segment file" above.  I
> > will rename that phrase to match the above terminology.  Patch attached
> > and applied.
> 
> Doesn't it refer to the backup file itself (the tar file of the data
> directory) ?

No.  That is what I thought it meant on first reading, but looking
closer it is referring to the numbered file, and the tar file has no
specific number.

> You do not want to start deleting WAL segments until that one is safely
> archived.

Right, but the point of the paragraph is that you need the WAL file that
goes with the backup history file number.

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
359-1001+  If your life is a hard drive,     |  13 Roberts Road +  Christ can be your backup.        |  Newtown Square,
Pennsylvania19073
 


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