IMHO, overall, there should be pros and cons of the current approach and the
new UNDo one (like Oracle?), depending on the workload. Under update-heavy
workload, the UNDO method may be better. OTOH, under the mostly-INSERT
workload (like data warehouse?), the current method will be better because it
writes no log for UNDO.
Furthermore, it maybe the best to be able to switch the method for each table
and/or tablespace. For example, in pgbench, history table uses the current
and other tables use the UNDO method. Is it time to introduce a pluggable
Because PostgreSQL is a follower in the UNDO approach, I think it will be
better to study other DBMSs well (Oracle and MySQL?). That includes not only
their manuals, but also whitepapers and books. Especially, I expect good books
to give deep knowledge on performance tuning and troubleshooting, from which we
will be able to know the cons that Oracle's materials don't state.
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