Hi,

Zeugswetter Andreas ADI SD wrote:
I don't insist the name and the default of the GUC parameter. I'm afraid wal_fullpage_optimization = on (default) makes some confusion because the default behavior becomes a bit different on WAL itself.


Seems my wal_fullpage_optimization is not a good name if it caused
misinterpretation already :-(

Amount of WAL after 60min. run of DBT-2 benchmark wal_add_optimization_info = off (default) 3.13GB
how about wal_fullpage_optimization = on (default)

The meaning of wal_fullpage_optimization = on (default)
would be the same as your wal_add_optimization_info = off (default).
(Reversed name, reversed meaning of the boolean value)

It would be there to *turn off* the (default) WAL full_page
optimization.
For your pg_compresslog it would need to be set to off. "add_optimization_info" sounded like added info about/for some
optimization
which it is not. We turn off an optimization with the flag for the
benefit
of an easier pg_compresslog implementation.

For pg_compresslog to remove full page writes, we need wal_add_optimization_info=on.


As already said I would decouple this setting from the part that sets
the "removeable full page" flag in WAL, and making the recovery able to
skip dummy records. This I would do unconditionally.

Andreas

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