From: | Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Lamar Owen <lamar(dot)owen(at)wgcr(dot)org>, pgsql-hackers(at)postgreSQL(dot)org |
Subject: | Re: [HACKERS] PG_UPGRADE status |
Date: | 1999-09-08 22:40:52 |
Message-ID: | 199909082240.SAA27668@candle.pha.pa.us |
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Lists: | pgsql-hackers |
> The issue with MVCC is that the state of a tuple isn't solely determined
> by what is in the disk file for its table; you have to also consult
> pg_log to see whether recent transactions have been committed or not.
> 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.
>
> OTOH, it seems to me that this was true in older releases as well
> (pg_log has always been critical data), so I guess I'm not clear on
> why pg_upgrade worked at all, ever...
At the end of pg_upgrade, there are the lines:
mv -f $OLDDIR/pg_log data
mv -f $OLDDIR/pg_variable data
echo "You may remove the $OLDDIR directory with 'rm -r $OLDDIR'."
exit 0
This is used to get the proper transaction status into the new
installation. Is the VACUUM added to pg_upgrade necessary?
--
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
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