Robert Muir created LUCENE-5721:
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Summary: Monotonic packed could maybe be faster
Key: LUCENE-5721
URL: https://issues.apache.org/jira/browse/LUCENE-5721
Project: Lucene - Core
Issue Type: Improvement
Reporter: Robert Muir
This compression is used in lucene for monotonically increasing offsets, e.g.
stored fields index, dv BINARY/SORTED_SET offsets, OrdinalMap (used for merging
and faceting dv) and so on.
Today this stores a +/- deviation from an expected line of y=mx + b, where b is
the minValue for the block and m is the average delta from the previous value.
Because it can be negative, we have to do some additional work to zigzag-decode.
Can we just instead waste a bit for every value explicitly (lower the minValue
by the min delta) so that deltas are always positive and we can have a simpler
decode? Maybe If we do this, the new guy should assert that values are actually
monotic at write-time. The current one supports "mostly monotic" but do we
really need that flexibility anywhere? If so it could always be kept...
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