Re: Add min and max execute statement time in pg_stat_statement

On 24/10/13 11:26, Peter Geoghegan wrote:

On Wed, Oct 23, 2013 at 2:57 PM, Gavin Flower
<GavinFlower@archidevsys.co.nz> wrote:

Looks definitely bimodal in the log version, very clear!

Yes, I feel that having a 32 log binary binned histogram (as Alvaro Herrera
suggested) would be very useful.

I'm having a hard time imagining how you'd actually implement that.
For example, this:

https://wiki.postgresql.org/wiki/Aggregate_Histogram

requires that a "limit" be specified ahead of time. Is there a
principled way to increase or decrease this kind of limit over time,
and have the new buckets contents "spill into each other"?

To smplify things, I'm using 5 buckets, but 32 would be better.
Assume first bucket width is 1ms.

bucket     range
  0              x =< 1ms
  1        1ms < x =< 2ms
  2        2ms < x =< 4ms
  3        4ms < x =< 8ms
  5        8ms < x