[
https://issues.apache.org/jira/browse/CASSANDRA-10520?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15885063#comment-15885063
]
Stefania commented on CASSANDRA-10520:
--------------------------------------
If the default value of {{min_compress_ratio}} is changed in the follow-up
commit, the cqlshlib tests should also be updated, see
[8bfa82769|https://github.com/apache/cassandra/commit/8bfa8276968db3d25d3e305a0fad156eeb904c34].
[{{test_describe}}|http://cassci.datastax.com/view/trunk/job/trunk_dtest/lastCompletedBuild/testReport/cqlsh_tests.cqlsh_tests/TestCqlsh/test_describe/]
and
[{{test_describe_mv}}|http://cassci.datastax.com/view/trunk/job/trunk_dtest/lastCompletedBuild/testReport/cqlsh_tests.cqlsh_tests/TestCqlsh/test_describe_mv/]
need fixing if not already done, thanks.
> Compressed writer and reader should support non-compressed data.
> ----------------------------------------------------------------
>
> Key: CASSANDRA-10520
> URL: https://issues.apache.org/jira/browse/CASSANDRA-10520
> Project: Cassandra
> Issue Type: Improvement
> Components: Local Write-Read Paths
> Reporter: Branimir Lambov
> Assignee: Branimir Lambov
> Labels: messaging-service-bump-required
> Fix For: 4.x
>
> Attachments: ReadWriteTestCompression.java
>
>
> Compressing uncompressible data, as done, for instance, to write SSTables
> during stress-tests, results in chunks larger than 64k which are a problem
> for the buffer pooling mechanisms employed by the
> {{CompressedRandomAccessReader}}. This results in non-negligible performance
> issues due to excessive memory allocation.
> To solve this problem and avoid decompression delays in the cases where it
> does not provide benefits, I think we should allow compressed files to store
> uncompressed chunks as alternative to compressed data. Such a chunk could be
> written after compression returns a buffer larger than, for example, 90% of
> the input, and would not result in additional delays in writing. On reads it
> could be recognized by size (using a single global threshold constant in the
> compression metadata) and data could be directly transferred into the
> decompressed buffer, skipping the decompression step and ensuring a 64k
> buffer for compressed data always suffices.
--
This message was sent by Atlassian JIRA
(v6.3.15#6346)
