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https://issues.apache.org/jira/browse/CASSANDRA-15379?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16962317#comment-16962317
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Joey Lynch commented on CASSANDRA-15379:
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Yeah I understand it's a bit late in the 4.0 cut, but I think we'll have users
running into this trying out the new Zstd compressor rather quickly (we ran
into it on the first cluster we dropped it on).
If you're not a fan of the defaults in yaml (I agree it's not great) to reduce
scope I could keep the change internal to C* entirely by adding a default
method on {{ICompressor}} such as:
{noformat}
default Set<String> unsuitableUseHints() {
return Collections.emptySet();
}{noformat}
Then the ZstdCompressor would yield a set with the string "flush" or something
and the flush code path would just use the default compressor in that case.
[~benedict] what do you think about this alternative?
> 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
>
> [~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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