Re: What does Page Layout version mean? (Was: Re: Reducing NUMERIC size for 8.3)

Zdenek Kotala <Zdenek.Kotala@Sun.COM> writes:
> I'm little bit confused when we introduce new page layout version? I 
> expect that new version become with changes with pageheader, tuple 
> header or data encoding (varlen/TOAST ...). But in case when there is 
> new data type internal implementation, there was not reason to update 
> version (see inet/cidr between 8.1 -> 8.2). Can me somebody clarify this?

Well, we've changed it when there was a benefit to an existing tool to
do so.  So far that's meant page header and tuple header changes.  If
we ever had a working in-place upgrade solution, I think we'd be willing
to make the page version account for datatype format changes too.
        regards, tom lane