| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)2ndquadrant(dot)com> |
| Cc: | Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, Mike Blackwell <mike(dot)blackwell(at)rrd(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>, Peter Geoghegan <pg(at)heroku(dot)com>, Claudio Freire <klaussfreire(at)gmail(dot)com> |
| Subject: | Re: Performance Improvement by reducing WAL for Update Operation |
| Date: | 2014-03-03 15:53:04 |
| Message-ID: | CA+TgmoYej2B2ZcWePUf3a06Fyk63wu9SbQrc8-9wxtkHJ_=HAQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Mon, Mar 3, 2014 at 10:38 AM, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
> On 2014-03-03 10:35:03 -0500, Robert Haas wrote:
>> On Mon, Mar 3, 2014 at 9:57 AM, Andres Freund <andres(at)2ndquadrant(dot)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?
Oh, maybe I need more caffeine.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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