Compression

Cassandra’s binary protocol supports optional compression of requests and responses. This reduces network traffic at the cost of a slight CPU overhead, therefore it will likely be beneficial when you have larger payloads, such as:

  • requests with many values, or very large values;
  • responses with many rows, or many columns per row, or very large columns.

To enable compression, set the following option in the configuration:

datastax-java-driver {
  advanced.protocol.compression = lz4 // or snappy
}

Compression must be set before opening a session, it cannot be changed at runtime.

Two algorithms are supported out of the box: LZ4 and Snappy. The LZ4 implementation is a good first choice; it offers fallback implementations in case native libraries fail to load and benchmarks suggest that it offers better performance and compression ratios over Snappy.

Both implementations rely on third-party libraries, declared by the driver as optional dependencies; if you enable compression, you need to explicitly depend on the corresponding library to pull it into your project.

LZ4

Dependency:

<dependency>
  <groupId>org.lz4</groupId>
  <artifactId>lz4-java</artifactId>
  <version>1.4.1</version>
</dependency>

Always double-check the exact LZ4 version needed; you can find it in the driver’s parent POM.

LZ4-java has three internal implementations (from fastest to slowest):

  • JNI;
  • pure Java using sun.misc.Unsafe;
  • pure Java using only “safe” classes.

It will pick the best implementation depending on what’s possible on your platform. To find out which one was chosen, enable INFO logs on the category com.datastax.oss.driver.internal.core.protocol.Lz4Compressor and look for the following message:

INFO  com.datastax.oss.driver.internal.core.protocol.Lz4Compressor  - Using LZ4Factory:JNI

Snappy

Dependency:

<dependency>
  <groupId>org.xerial.snappy</groupId>
  <artifactId>snappy-java</artifactId>
  <version>1.1.2.6</version>
</dependency>

Always double-check the exact Snappy version needed; you can find it in the driver’s parent POM.