Bruce Momjian napsal(a):
Zdenek Kotala wrote:
In the last week community made decision about pg_upgrade project and its
implementation. I would like to try summarize this conclusion and I add other
topic which should be finished for 8.4.
Convert on read has been selected as a good way, because it is not invasive and
does not limit fresh database. But, this way needs core modification which
allows to do online in-place upgrade. It means no online in-place upgrade to 8.4
will be implemented. Sorry about that, but we need move forward and there is not
easy way without core modification to do it.
As I mentioned manytimes before there are two major issues with convert on read
and one small issue.
1) Data does not fit on the new page. It will be solve by pre-upgrade check
which reserve space on each page, before upgrade.
Rather than specifying free space as an amount, I was thinking of having
a boolean like 'ready_for_upgrade' and the system internally would know
how much free space for each page and tuple.
You need booth, flag which shows you that the relation/database is ready for
upgrade and free space reservation configuration for each column. System cannot
know it because PostgreSQL is not oracle :-). It does not know what will happend
during next version development :-). It have to be setup by pre-upgrade script.
Zdenek
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