On Thu, Jun 25, 2015 at 6:58 AM, Ilya Kosmodemiansky
<ilya.kosmodemiansky@postgresql-consulting.com> wrote:
> 1. Some sort of histogram of top waits within entire database by pid.
> That will be an approximate one, because I hardly believe there is a
> possibility to make a precise one without significant overhead.
You could compute that histogram from the data I am proposing to
publish. Indeed, it's hard to see what other fundamentally different
mechanism you would use. The backends have got to advertise their
state in shared memory someplace, which my proposal would do, and then
you've got to poll that data somewhere else, which I'm not proposing
to do but it could be done.
> 2. Some cyclic buffer of more precise wait statistic inside each
> worker. Sampling may be turned on if we see some issues in histogram
> (1) and want to have some more details.
That could be built on top of this, too.
Both of those ideas require the information that my proposal would
provide, but the information this proposal would provide is still
useful if we don't do those other things.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company