code-shoily / yog_ex / 63799b6cae99b720724b60a7d8c0e1512d7d977e

93%

Build Type

push

github

Committed by code-shoily

Commit Message

fix: use full 32-bit range for phash2 in HLL estimator

:erlang.phash2/1 only returns values in [0, 2^27 - 1]. The HLL
implementation expected a 32-bit hash for its leading-zero count,
so the always-zero high bits biased estimates by ~30x past the
linear-counting cutoff. Pass an explicit 2^32 range to phash2/2
to fix the bias.

Add a regression test that validates accuracy for cardinalities
well above the linear-counting threshold (~2.5k for 1024 regs).

Coverage Stats

1 of 1 new or added line in 1 file covered. (100.0%)

2 existing lines in 1 file now uncovered.

10521 of 11306 relevant lines covered (93.06%)

17339.94 hits per line