On Tue, Jul 2, 2013 at 5:19 AM, 高健 <luckyjackgao(at)gmail(dot)com> wrote:
> Hello:
> I looked into the source code, and I think I now understand it:
> cmin and cmax are same! The documentation is too old now.
Yes, you figured it out.
For short: cmin and cmax are overlapped fields and are used within the
same transaction to identify the command that changed a tuple, so that
in-transaction commands can be ordered and, therefore, tuple
visibility can be calculated.
Luca