Re: Patch: add timing of buffer I/O requests

On Mon, Nov 28, 2011 at 2:54 AM, Greg Smith <greg(at)2ndquadrant(dot)com> wrote:
> The real problem with this whole area is that we know there are
> systems floating around where the amount of time taken to grab timestamps
> like this is just terrible.

Assuming the feature is off by default (and I can't imagine we'd
consider anything else), I don't see why that should be cause for
concern. If the instrumentation creates too much system load, then
don't use it: simple as that. A more interesting question is "how
much load does this feature create even when it's turned off?".

The other big problem for a patch of this sort is that it would bloat
the stats file. I think we really need to come up with a more
scalable alternative to the current system, but I haven't looked the
current system in enough detail to have a clear feeling about what
such an alternative would look like.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company