compression = { compression_map }

Configure the compression_map by specifying the compression algorithm class followed by the subproperties in simple JSON format.

Implement custom compression classes using the org.apache.cassandra.io.compress.ICompressor interface.

compression = {
   ['class' : '<compression_algorithm_name>',
     'chunk_length_in_kb' : '<value>',
     'crc_check_chance' : '<value>',]
   | 'sstable_compression' : '']
}
class

Sets the compressor name. DataStax Enterprise provides the following built-in classes:

  • LZ4Compressor

  • SnappyCompressor

  • DeflateCompressor

    Use only compression implementations bundled with DSE.

Choosing the right compressor depends on your requirements for space savings over read performance. LZ4 is fastest to decompress, followed by Snappy, then by Deflate. Compression effectiveness is inversely correlated with decompression speed. The extra compression from Deflate or Snappy is not enough to make up for the decreased performance for general-purpose workloads, but for archival data they may be worth considering.

Default: LZ4Compressor.

chunk_length_in_kb

Size (in KB) of the block. On disk, SSTables are compressed by block to allow random reads. Values larger than the default value might improve the compression rate, but increases the minimum size of data to be read from disk when a read occurs. The default value is a good middle ground for compressing tables. Adjust compression size to account for read/write access patterns (how much data is typically requested at once) and the average size of rows in the table.

Default: 64.

crc_check_chance

When compression is enabled, each compressed block includes a checksum of that block for the purpose of detecting disk bit rot and avoiding the propagation of corruption to other replica. This option defines the probability with which those checksums are checked during read. By default they are always checked. Set to 0 to disable checksum checking and to 0.5, for instance, to check them on every other read.

Default: 1.0.

sstable_compression

Disables compression. Specify a null value.

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