On 5/10/19 8:56 AM, bb ddd wrote:
> Thanks for the reply. Here it is: https://explain.depesz.com/s/LQCS
>
> My main trouble is not with this exact case, but i am looking for a general description of the algorithm how those
numbersare calculated. In the meanwhile i also constructed a couple of artificial tables to experiment with and see how
thesenumbers change, and am pretty sure my guesses there in the original question are quite close to what is going on,
butwould be so much easier to read explain plans, if there was some documentation about how the expected rows are
calculatedfor different nodes, in different contexts (like when loops=1 vs loops>1) maybe what statistics they use, how
theydepend on the numbers of their child nodes etc.
>
>
How about?:
https://www.postgresql.org/docs/11/using-explain.html
--
Adrian Klaver
adrian.klaver@aklaver.com