Re: Differential backup

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.

--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.