Re: Performance Improvement by reducing WAL for Update Operation - Mailing list pgsql-hackers

On 2014-03-03 10:35:03 -0500, Robert Haas wrote:
> On Mon, Mar 3, 2014 at 9:57 AM, Andres Freund <andres@2ndquadrant.com> wrote:
> > Hm, I think all it needs to do disable delta encoding if
> > need_tuple_data (which is dependent on wal_level=logical).
> 
> Why does it need to do that?  The logical decoding stuff should be
> able to reverse out the delta encoding.

Against what should it perform the delta? Unless I misunderstand how the
patch works, it computes the delta against the old tuple in the heap
page?

Greetings,

Andres Freund

-- Andres Freund                       http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
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