Re: Replication/cloning: rsync vs modification dates?

On 7/16/12, Sergey Konoplev <sergey(dot)konoplev(at)postgresql-consulting(dot)com> wrote:
> On Mon, Jul 16, 2012 at 8:01 PM, Chris Angelico <rosuav(at)gmail(dot)com> wrote:
>> On Tue, Jul 17, 2012 at 1:58 AM, Michael Nolan <htfoot(at)gmail(dot)com> wrote:
>>> As I understand the docs for rsync, it will use both mod time and file
>>> size
>>> if told not to do checksums.
>
> I wonder if it is correct in general to use mtime and size to perform
> these checks from the point of view of PostgreSQL.
>
> If it works with the current version then is there a guaranty that it
> will work with the future versions?

There are many things for which no guarantee of future compatibility
(or sufficiency) are the case.

For that matter, there's really no assurance that timestamp+size is
sufficient NOW.

But checksums aren't 100% reliable, either. without doing a byte by
byte comparison of two files, there's no way to ensure they are
identical.
--
Mike Nolan