# and look at latency:
# no parts = 0.071 ms
# 1 hash = 0.071 ms (did someone optimize this case?!)
# 2 hash ~ 0.126 ms (+ 0.055 ms)
# 50 hash ~ 0.155 ms
# 100 hash ~ 0.178 ms
# 150 hash ~ 0.232 ms
# 200 hash ~ 0.279 ms
# overhead ~ (0.050 + [0.0005-0.0008] * nparts) ms
It is linear?
Good question. I would have hoped affine, but this is not very clear on these
data, which are the median of about five runs, hence the bracket on the slope
factor. At least it is increasing with the number of partitions. Maybe it
would be clearer on the minimum of five runs.
Here is a fellow up.
On the minimum of all available runs the query time on hash partitions is
about:
0.64375 nparts + 118.30979 (in µs).
So the overhead is about 47.30979 + 0.64375 nparts, and it is indeed
pretty convincingly linear as suggested by the attached figure.
--
Fabien.
