Re: [HACKERS] PG_UPGRADE status

> Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us> writes:
> >> pg_upgrade doesn't import the old pg_log into the new database (and
> >> can't very easily, since the new database will have its own), so there's
> >> a problem with recent tuples possibly getting lost.
>
> > At the end of pg_upgrade, there are the lines:
> > mv -f $OLDDIR/pg_log data
> > mv -f $OLDDIR/pg_variable data
> > This is used to get the proper transaction status into the new
> > installation. Is the VACUUM added to pg_upgrade necessary?
>
> I'm sorry, I had that backwards (knew I shoulda checked the code).
>
> pg_upgrade *does* overwrite the destination pg_log, and what that
> means is that incoming tuples in user relations should be fine.
> What's at risk is recently-committed tuples in the system relations,
> notably the metadata that pg_upgrade has just inserted for those
> user relations.
>
> The point of the VACUUM is to try to ensure that everything
> in the system relations is marked as certainly committed (or
> certainly dead) before we discard the pg_log information.
> I don't recall ever hearing from Vadim about whether that
> is a trustworthy way of doing it, however.
>
> One thing that occurs to me just now is that we probably need
> to vacuum *each* database in the new installation. The patch
> I added to pg_dump doesn't do the job because it only vacuums
> whichever database was dumped last by pg_dumpall...
>

I have modified pg_upgrade to vacuum all databases, as you suggested.

copy pg_shadow from stdin;
\.
-> VACUUM;
\connect template1 postgres
create database test;
\connect test postgres
\connect - postgres
CREATE TABLE "t1" (

I left your vacuum in there to vacuum the last database. This should
help.

--
Bruce Momjian | http://www.op.net/~candle
maillist(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
+ If your life is a hard drive, | 830 Blythe Avenue
+ Christ can be your backup. | Drexel Hill, Pennsylvania 19026