| From: | Jim Nasby <jim(at)nasby(dot)net> |
|---|---|
| To: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
| Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Future In-Core Replication |
| Date: | 2012-04-26 18:40:51 |
| Message-ID: | 4F9996B3.6080205@nasby.net |
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| Lists: | pgsql-hackers |
On 4/26/12 7:41 AM, Simon Riggs wrote:
> 5. WRITE-SCALEABLE - the ability to partition data across nodes in a
> way that allows the solution to improve beyond the write rate of a
> single node.
It would be valuable to look at READ-SCALEABLE as well; specifically a second form of "synchronous" replication where you can read from a slave "immediately" after transaction commit and have the changes be visible. That ability would make it trivial to spread reads off of the master database.
My hope is this wouldn't be horribly painful to achieve if we relaxed the need to fsync the corresponding WAL on the slave; kind of the opposite of the semi-synchronous mode we have now. My theory is that thanks to full page writes a slave should normally have the necessary pages to handle a WAL record in cache, so actually applying the WAL change shouldn't be horribly slow.
--
Jim C. Nasby, Database Architect jim(at)nasby(dot)net
512.569.9461 (cell) http://jim.nasby.net
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