Re: Actual Cost

On 2/17/19 3:40 AM, David Fetter wrote:
> On Sat, Feb 16, 2019 at 03:10:44PM -0800, Donald Dong wrote:
>> Hi,
>>
>> When explaining a query, I think knowing the actual rows and pages
>> in addition to the operation type  (e.g seqscan) would be enough to
>> calculate the actual cost. The actual cost metric could be useful
>> when we want to look into how off is the planner's estimation, and
>> the correlation between time and cost. Would it be a feature worth
>> considering?
> 
> As someone not volunteering to do any of the work, I think it'd be a
> nice thing to have.  How large an effort would you guess it would be
> to build a proof of concept?
> 

I don't quite understand what is meant by "actual cost metric" and/or
how is that different from running EXPLAIN ANALYZE.

regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services