This microbenchmark tests performance of the galloping reader
optimization. A combining reader that merges results from four other
readers is created. Each sub-reader provides a range of 32 clustering
rows that is disjoint from others. All sub-readers return rows from
the same partition. An improvement can be observed after introducing the
galloping reader optimization.
As for other benchmarks from the "combined" group, results are pretty
close to the old ones. The only one that seems to have suffered slightly
is combined.many_overlapping.
Median times from a single run of perf_mutation_readers.combined:
(1s run duration, 5 runs per benchmark, release mode)
test name before after improvement
one_row 49.070ns 48.287ns 1.60%
single_active 61.574us 61.235us 0.55%
many_overlapping 488.193us 514.977us -5.49%
disjoint_interleaved 57.462us 57.111us 0.61%
disjoint_ranges 56.545us 56.006us 0.95%
overlapping_partitions_disjoint_rows 127.039us 80.849us 36.36%
Same results, normalized per mutation fragment:
test name before after improvement
one_row 16.36ns 16.10ns 1.60%
single_active 109.46ns 108.86ns 0.55%
many_overlapping 216.97ns 228.88ns -5.49%
disjoint_interleaved 102.15ns 101.53ns 0.61%
disjoint_ranges 100.52ns 99.57ns 0.95%
overlapping_partitions_disjoint_rows 246.38ns 156.80ns 36.36%
Tested on AMD Ryzen Threadripper 2950X @ 3.5GHz.
81883a9f2e