Chris Lohfink created CASSANDRA-21550:
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Summary: Zero-copy sstable splitting for anticompaction, and
partial-sstable zero-copy streaming
Key: CASSANDRA-21550
URL: https://issues.apache.org/jira/browse/CASSANDRA-21550
Project: Apache Cassandra
Issue Type: New Feature
Reporter: Chris Lohfink
Anticompaction and range streaming both spend most of their cost re-doing work
whose
result they already have on disk. Anticompaction rewrites every row of an
sstable
through three writers only to place each partition into a repaired, transient or
unrepaired child. Streaming a subset of an sstable's ranges takes the
row-by-row path,
where the sender is cheap (whole compression chunks are sent verbatim) but the
receiver
decompresses, deserialises, re-serialises and recompresses every row and then
rebuilds
the index, filter and summary it could have been handed.
Both are avoidable when the bytes wanted are a contiguous run of the parent's
compression chunks: the chunks can be copied (or extent-shared) verbatim and
every other
component rebuilt from an index-only pass, with no row deserialised on either
side.
This adds that machinery and the two callers for it. Both are off by default.
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