On 8/2/07, Andrew Hammond <andrew.george.hammond at gmail.com> wrote:
> On 7/30/07, Laurent Raufaste <laurent at over-blog.com> wrote:
> > Here's our issue: In the sl_status view I notice that the st_lag_time is
> > always between 1 and many seconds: it goes up to 10 seconds regularly,
> > and approximatively one time a day, there is always a slave reaching 1
> > min, for example while vacuuming.
>
> 1 to 10 seconds is pretty good. If there aren't any changes to tables on the
> origin then SYNC events are only generated every 10 seconds (by default). Do
> you have enough DML (inserts, updates and deletes) traffic to keep the syncs
> flowing? Even if there are plenty of changes to record, by default, syncs
> are only generated every 2 seconds, so any lag time of less than 2 seconds
> is effectively as up to date as possible.

slony1-1.2.10/share/slon.conf-sample (as well as the 1.2.10
documentation has different defaults (100ms and 1000ms for
sync_interval and sync_interval_timeout which differs from the
documentation at http://slony.info/documentation/ (which appears to be
version 1.2.6 listing defaults of 10000ms and 60000ms).

> If it's because of inactivity, then you can decrease your
> sync_interval_timeout, however the real effect of this is to just make the
> lag time look better. (There's an edge case here involving sequences)

So the edge case only involve sequences? I found the explanation for
sync_interval_timeout a bit confusing...

-Dave