This API (unexported) will estimate the amount of memory needed to execute
a search query over an index before the collector begins data collection.
Sample estimates for certain queries:
{Size: 10, BenchmarkUpsidedownSearchOverhead}
ESTIMATE BENCHMEM
TermQuery 4616 4796
MatchQuery 5210 5405
DisjunctionQuery (Match queries) 7700 8447
DisjunctionQuery (Term queries) 6514 6591
ConjunctionQuery (Match queries) 7524 8175
Nested disjunction query (disjunction of disjunctions) 10306 10708
…
This change adds a zap PostingsIterator.nextBytes() method, which is
similar to Next(), but instead of returning a Posting instance,
nextBytes() returns the encoded freq/norm and location byte slices.
The zap merge code then provides those byte slices directly to the
intCoder's via a new method, intCoder.AddBytes(), thereby avoiding
having to encode many uvarint's.
During zap segment merging, a new zap PostingsIterator was allocated
for every field X segment X term.
This change optimizes by reusing a single PostingsIterator instance
per persistMergedRest() invocation.
And, also unused fields are removed from the PostingsIterator.
The zap DictionaryIterator Next() was incorrectly returning the
postingsList offset as the term count. As part of this, refactored
out a PostingsList.read() helper method.
Also added more merge unit test scenarios, including merging a segment
for a few rounds to see if there are differences before/after merging.
The zap SegmentBase struct is a refactoring of the zap Segment into
the subset of fields that are needed for read-only ops, without any
persistence related info. This allows us to use zap's optimized data
encoding as scorch's in-memory segments.
The zap Segment struct now embeds a zap SegmentBase struct, and layers
on persistence. Both the zap Segment and zap SegmentBase implement
scorch's Segment interface.
With this change, there are no more memory allocations in the calls to
PostingsIterator.Next() in the micro benchmarks of bleve-query. On a
dev macbook, on an index of 50K wikipedia docs, using high frequency
search of "text:date"...
400 qps - upsidedown/moss
565 qps - scorch before
680 qps - scorch after
abhinavdangeti