On Tue, 2010-04-27 at 09:50 -0400, Alvaro Herrera wrote:
> Simon Riggs wrote:
> > Thinking about allowing a backup to tell which files have changed in the
> > database since last backup. This would allow an external utility to copy
> > away only changed files.
> > Now there's a few ways of doing this and many will say this is already
> > possible using file access times.
> > An explicit mechanism where Postgres could authoritatively say which
> > files have changed would make many feel safer, especially when other
> > databases also do this.
> > We keep track of which files require fsync(), so we could also keep
> > track of changed files using that same information.
> Why file level? Seems a bit too coarse (particularly if you have large
> file support enabled). Maybe we could keep block-level last change info
> in a separate fork.
Block-level is mostly available by using LSN, you just need to scan the
file. So block level seems not useful enough for the extra overhead.
File-level would be sufficient for most purposes. If you wanted to go
finer grained you can then scan just the files that have changed.
Simon Riggs www.2ndQuadrant.com
In response to
pgsql-hackers by date
|Next:||From: Kevin Grittner||Date: 2010-04-27 13:59:03|
|Subject: Re: Differential backup|
|Previous:||From: Tom Lane||Date: 2010-04-27 13:51:36|
|Subject: Re: Wierd quirk of HS/SR, probably not fixable |