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https://issues.apache.org/jira/browse/CASSANDRA-21550?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Chris Lohfink updated CASSANDRA-21550:
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Description: 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. (was:
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.)
> 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
> Priority: Normal
> Time Spent: 10m
> Remaining Estimate: 0h
>
> 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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