| From: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Andres Freund <andres(at)2ndquadrant(dot)com>, pgsql-hackers(at)postgresql(dot)org, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Daniel Farina <daniel(at)heroku(dot)com> |
| Subject: | Re: [PATCH 10/16] Introduce the concept that wal has a 'origin' node |
| Date: | 2012-06-19 21:58:53 |
| Message-ID: | CA+U5nMKsUS5mgbPttUwSL74gRZBOtpp9YCOtj0CNnmCujapLdg@mail.gmail.com |
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| Lists: | pgsql-hackers |
On 20 June 2012 05:46, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> It seems to me that you are intent on using the WAL stream as the
> logical change stream. I think that's a bad design. Instead, you
> should extract changes from WAL and then ship them around in a format
> that is specific to logical replication.
The proposal is to read the WAL in order to generate LCRs. The
information needs to be in the original data in order to allow it to
be passed onwards.
In a multi-master config there will be WAL records with many origin
node ids at any time, so this information must be held at WAL record
level not page level.
--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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