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Re: Issues Outstanding for Point In Time Recovery (PITR)

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Hannu Krosing <hannu@tm.ee>
Cc: Barry Lind <barry@xythos.com>, Patrick Macdonald <patrickm@redhat.com>, Zeugswetter Andreas SB SD <ZeugswetterA@spardat.at>, "J. R. Nield" <jrnield@usol.com>, PostgreSQL Hacker <pgsql-hackers@postgresql.org>
Date: 2002-07-09T15:26:55Z
Lists: pgsql-hackers 
Hannu Krosing <hannu@tm.ee> writes:
> 1) record the lowest uncommitted transaction number (LUTN) , this may
> have problems with wraparound, but I guess they are solvable. Disllow
> VACUUM. Do a CHECKPOINT ('alter database begin backup')
> 3) make a file-level (.tar) backup of data directory.
> 4) Allow VACUUM. ('alter database end backup')

Transactions don't necessarily commit in sequence number order, so the
concept of LUTN seems meaningless.

Why is it necessary (or even good) to disallow VACUUM?  I really dislike
a design that allows the DBA to cripple the database by forgetting the
last step in a (long) process.

			regards, tom lane