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https://issues.apache.org/jira/browse/CASSANDRA-15379?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Dinesh Joshi updated CASSANDRA-15379:
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Status: Changes Suggested (was: Review In Progress)
Hi [~jolynch], thanks for the patch. I went over it and it looks generally
good. On a high level the only concern I have is introducing a
{{NoOpCompressor}} may lead to some performance issues compared to our current
state. This is mainly due to Java JIT's inability to optimize megamorphic call
sites. However, I think this is just a theory and we should try and validate it
using an actual performance test. IMHO, the advantages that you have laid out
would outweight a bit of performance penalty.
Other than that, I had some code related feedback. It fixes the
{{DatabaseDescriptorRefTest}} and also makes minor structural modifications for
safety and clarity. I have illustrated in my branch
[here|https://github.com/apache/cassandra/compare/trunk...dineshjoshi:CASSANDRA-15379-review?expand=1].
Please feel free to cherry pick the commits in your branch.
> Make it possible to flush with a different compression strategy than we
> compact with
> ------------------------------------------------------------------------------------
>
> Key: CASSANDRA-15379
> URL: https://issues.apache.org/jira/browse/CASSANDRA-15379
> Project: Cassandra
> Issue Type: Improvement
> Components: Local/Compaction, Local/Config, Local/Memtable
> Reporter: Joey Lynch
> Assignee: Joey Lynch
> Priority: Normal
> Fix For: 4.0-alpha
>
>
> [~josnyder] and I have been testing out CASSANDRA-14482 (Zstd compression) on
> some of our most dense clusters and have been observing close to 50%
> reduction in footprint with Zstd on some of our workloads! Unfortunately
> though we have been running into an issue where the flush might take so long
> (Zstd is slower to compress than LZ4) that we can actually block the next
> flush and cause instability.
> Internally we are working around this with a very simple patch which flushes
> SSTables as the default compression strategy (LZ4) regardless of the table
> params. This is a simple solution but I think the ideal solution though might
> be for the flush compression strategy to be configurable separately from the
> table compression strategy (while defaulting to the same thing). Instead of
> adding yet another compression option to the yaml (like hints and commitlog)
> I was thinking of just adding it to the table parameters and then adding a
> {{default_table_parameters}} yaml option like:
> {noformat}
> # Default table properties to apply on freshly created tables. The currently
> supported defaults are:
> # * compression : How are SSTables compressed in general (flush,
> compaction, etc ...)
> # * flush_compression : How are SSTables compressed as they flush
> # supported
> default_table_parameters:
> compression:
> class_name: 'LZ4Compressor'
> parameters:
> chunk_length_in_kb: 16
> flush_compression:
> class_name: 'LZ4Compressor'
> parameters:
> chunk_length_in_kb: 4
> {noformat}
> This would have the nice effect as well of giving our configuration a path
> forward to providing user specified defaults for table creation (so e.g. if a
> particular user wanted to use a different default chunk_length_in_kb they can
> do that).
> So the proposed (~mandatory) scope is:
> * Flush with a faster compression strategy
> I'd like to implement the following at the same time:
> * Per table flush compression configuration
> * Ability to default the table flush and compaction compression in the yaml.
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