On Tue, Oct 26, 2010 at 10:13 AM, Rob Wultsch <wultsch@gmail.com> wrote:
> The double write buffer is one of the few areas where InnoDB does more
> IO (in the form of fsynch's) than PG. InnoDB also has fuzzy
> checkpoints (which help to keep dirty pages in memory longer),
> buffering of writing out changes to secondary indexes, and recently
> tunable page level compression.
Baron Schwartz was talking to me about this at Surge. I don't really
understand how the fuzzy checkpoint stuff works, and I haven't been
able to find a good description of it anywhere. How does it keep
dirty pages in memory longer? Details on the other things you mention
would be interesting to hear, too.
> Given that InnoDB is not shipping its logs across the wire, I don't
> think many users would really care if it used the double writer or
> full page writes approach to the redo log (other than the fact that
> the log files would be bigger). PG on the other hand *is* pushing its
> logs over the wire...
So how is InnoDB doing replication? Is there a second log just for that?
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
