On Thu, Apr 21, 2011 at 10:33 AM, Florian Weimer
<fweimer@bfk.de> wrote:
* Greg Smith:
> The fact that every row update can temporarily use more than 8K means
> that actual write throughput on the WAL can be shockingly large. The
> smallest customer I work with regularly has a 50GB database, yet they
> write 20GB of WAL every day. You can imagine how much WAL is
> generated daily on systems with terabyte databases.
Interesting. Is there an easy way to monitor WAL traffic in away? It
does not have to be finegrained, but it might be helpful to know if
we're doing 10 GB, 100 GB or 1 TB of WAL traffic on a particular
database, should the question of SSDs ever come up.
If you archive your WAL files, wouldn't that give you a pretty good indication of write activity?
For example, yesterday I archived 74 WAL files, each 16MB. That's about 1.2 gigabytes for a database that takes up about 58 GB.
--
Mike Nolan