Proposal to include CASSANDRA-14482 (ZSTD Support) in 4.0 release

[Sushma Devendrappa <sd...@instagram.com>]

Hi,

I am checking to see if we can include CASSANDRA-1448 in 4.0 release which provides ZSTD compressor for Cassandra. Currently changes are under review, implementation has unit test coverage similar to other compressors, also tested in Instagram’s shadow clusters.
Implementation structure is similar to other Cassandra’s iCompressor, but with extra compression_level configuration which is table/CF level. ZSTD supports levels 1-22. 1 being fastest and 22 being best at compression ratio.
According to benchmarks most of the use cases that I have tested gives better speed with ZSTD  than LZ4 and Deflate at same compression ratio.
ZSTD Compressor changes will not affect any tests, adding it to 4.0 gives an advantage to experiment and use ZSTD in production systems and enhance further. There is additional discussions on the Jira with a good summary given by Joey based on his testing of ZSTD as well.
--Sushma