Re: Savepoints

Vadim Mikheev <vmikheev@sectorbase.com>

From: "Mikheev, Vadim" <vmikheev@SECTORBASE.COM>
To: "'Bruce Momjian'" <pgman@candle.pha.pa.us>, PostgreSQL-development <pgsql-hackers@postgreSQL.org>
Date: 2002-01-23T23:22:42Z
Lists: pgsql-hackers
> I have talked in the past about a possible implementation of
> savepoints/nested transactions.  I would like to more formally outline
> my ideas below.

Well, I would like to do the same -:)

> ...
> There is no reason for other backend to be able to see savepoint undo
> information, and keeping it private greatly simplifies the
> implementation.

Yes... and requires additional memory/disk space: we keep old records
in data files and we'll store them again...

How about: use overwriting smgr + put old records into rollback
segments - RS - (you have to keep them somewhere till TX's running
anyway) + use WAL only as REDO log (RS will be used to rollback TX'
changes and WAL will be used for RS/data files recovery).
Something like what Oracle does.

Vadim