Re: Transaction-controlled robustness for replication - Mailing list pgsql-hackers

From Markus Wanner
Subject Re: Transaction-controlled robustness for replication
Date
Msg-id 48A2006F.5040100@bluegap.ch
Whole thread Raw
In response to Re: Transaction-controlled robustness for replication  (Robert Hodges <robert.hodges@continuent.com>)
Responses Re: Transaction-controlled robustness for replication  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Hi,

Robert Hodges wrote:
> Could you expand on why logical application of WAL records is impractical in
> these cases?  This is what Oracle does.  Moreover once you are into SQL a
> lot of other use cases immediately become practical, such as large scale
> master/slave set-ups for read scaling.

I cannot speak for Tom, but what strikes me as a strange approach here 
is using the WAL for "logical application" of changes. That's because 
the WAL is quite far away from SQL, and thus from a "logical 
representation" of the data. It's rather pretty physical, meaning it's 
bound to a certain Postgres release and CPU architecture.

A more "logical" exchange format certainly poses less problems across 
releases, encodings and CPU architectures. Or even across RDMSen. But 
hey, let's see what Simon comes up with...

Regards

Markus Wanner



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