Deterministic and Non -deterministics

 

Deterministic and Non-deterministic

Two approximate algorithms are offered for the approximate percentile functions:

• Non-deterministic: fastest method, whenever reproducibility is not required. This is the default method.
• Deterministic: slightly slower, but delivers deterministic results.

Note that the differences will not be apparent with the small dataset in use here.

REM Approximate median, NON DETERMINISTIC

select approx_median(volume), approx_median(volume,'ERROR_RATE') 
from approxt where state = 'CA';

REM Approximate median, DETERMINISTIC

select approx_median(volume deterministic), approx_median(volume deterministic,'ERROR_RATE') 
from approxt 
where state = 'CA';

REM Approximate percentile, DETERMINISTIC

select approx_percentile(0.1 deterministic) within group (order by volume) 
from approxt where state = 'CA';