Re: WIP: Pg_upgrade - page layout converter (PLC) hook

Tom Lane napsal(a):
> Heikki Linnakangas <heikki@enterprisedb.com> writes:
>> Zdenek Kotala wrote:
>>> I attached patch which implemented page layout converter (PLC) hook. It
>>> is base stone for in-place upgrade.
> 
>> I agree it's an important piece of the puzzle, but not the most 
>> complicated one by far.
> 
> In fact, it's not even worth thinking about at this stage, because you
> couldn't meaningfully use or test it before you have dealt with catalog
> update issues.

It is egg and chicken problem. I'm able to test it because I use own script for 
catalog upgrade (similar to pg_migrator).

> Even more to the point, we already had consensus that we would try to
> avoid page-level changes once we had a working migration solution,
> so it's not clear that there will ever be a big need for page layout
> conversion.

I'm really not convenient that page layout will never changed in the future. It 
is modified each second version. And you need way how to convert data from 
pre8.4 versions as well. And PLC convert page header, tuple headers and it could 
convert also data items.

> I think this patch is a complete waste of effort at this stage, and
> should not be considered for application until we have a context in
> which we could meaningfully test it.

I will send PLC code soon. I'm now testing it. For catalog upgrade you can use 
pg_migrator or pg_upgrade.sh script 
(http://src.opensolaris.org/source/xref/sfw/usr/src/cmd/postgres/postgresql-upgrade/)
    Zdenek