Cassandra compression

Compression

• Compression maximizes the storage capacity of Cassandra nodes by reducing the volume of data on disk and disk I/O, particularly for read-domainated workloads.
• Cassandra quickly finds the location of rows in the SSTable index and decompresses the relevant row chunks.

 

New Storage engine (Cassandra 3.0+)

• Compression is important for Cassandra 2.2, but Cassandra 3.0 and later uses a new storage engine that dramatically reduces disk volume automatically.
  • https://www.datastax.com/blog/putting-some-structure-storage-engine

 

Cassandrar compression (vs traditional relation databases)

• Write Performance is not negatively impacted by compression in Cassandra as it is in traditional databases.
• In traditional relational databases, writes require overwrites to existing data files on disk.
• The database has to locate the relevant pages on disk, decompress them, overwrite the relevant data, and finally recompress.
• In a relational database, compression is an expensive operation in terms of. CPU cycles and disk I/O.
• Because Cassandra SSTable data files are immutable, there is no recompression cycle necessary in order to process writes.
• SSTables are compressed only once when they are written to disk.
• Writes on compressed tables can show up to a 10% performance improvement.