about parallel query

[sunww <sp...@outlook.com>]

Hi,I note phoenix can runs queries in parallel automatically.But I don't understand    this formula:
-------------------------------t is the target concurrencym is the max concurrencyr is the number of regions we need to scan
if r >= t    scan using regional boundaries else if r/2 > t    split each region in s splits such that: s = max(x) where s * x < m else    split each region in s splits such that:  s = max(x) where s * x < t -------------------------------
if there is only one regions to scan and target concurrency、max concurrency  are default value.how many parallelization  can be excute
Thanks