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stephen9834 asked Erick Ramirez commented

Key cache feature in DSE 6.7

Hi Team,

I am exploring new version of dse i.e 6.7. just want to know wheather key cache has been removed or deprecated from dse 6.7 as i didnt find any entry in configurations please help me in this

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Erick Ramirez answered Erick Ramirez commented

[UPDATED] The key cache is no longer used in the newer SSTable format since DSE 6.0.

The key_cache_* properties were removed from cassandra.yaml since they are no longer used in the new SSTable format (see the Changes and enhancements portion of the DSE 6.0.0 Core section of the Release Notes).

Some of the settings are retained only for backward-compatibility, particularly when upgrading from an older version of DSE whose SSTable format still uses the key cache. Cheers!

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Thanks for the support Erick , Actually key cache is enabled but still when i am checking nodetool info getting below output :

Key Cache : entries 0, size 0 bytes, capacity 100 MiB, 0 hits, 0 requests, NaN recent hit rate, 14400 save period in seconds

AS per output key cache hit rate is 0 it means i am not getting benefit of key cache.

I don't see any parameter in cassandra.yaml for Key Cache .

do i need to add any other configuration in cassandra.yaml in order to get benefit of key cache

i am using version dse 6.7 .

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Thank you for the additional info. I now understand what you're referring to and I've updated my answer accordingly. Cheers!

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stephen9834 avatar image stephen9834 Erick Ramirez ♦♦ ·

Thanks for the information

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@Erick Ramirez Then how can one achieve cache benefit with this version ? When i was testing cache feature and benefits during lab test I was getting good read result with key cache on dse 5.1. Can you give your opinion on what should be use in this new version to get better read latency results so that i can try out the same. suggest anything related to caching.

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For what it's worth, the key cache is a cache of the partition index in older versions of Cassandra. The SSTable format has changed in newer versions so the keys are no longer cached. DSE 6.0+ has Advanced Performance which has an asynchronous thread-per-core architecture that's 2x faster than the old SEDA. Cheers!

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