Re: Online backup of PostgreSQL data.

John R Pierce wrote:
> to copy the data directory and have it be useful you need to bracket the copy with calls to
> pg_start_backup() and pg_stop_backup() .... this ensures the data files are coherent.   this is in
> fact what pg_basebackup does for you....

I apologize for my fussiness, but this is a misconception I encounter so frequently
that I have to speak up.

The file system copy does not become consistent (isn't that what you meant?) if it
is surrounded by pg_start_backup() and pg_stop_backup().  What happens is that
a) a backup.label file is created that tells recovery where to start
b) more WAL is generated so that all changes can be replayed safely.

Yours,
Laurenz Albe