Compression

The Java driver supports compression of messages to and from MongoDB servers. The driver implements the two algorithms that are supported by MongoDB servers:

• Snappy: Snappy compression can be used when connecting to MongoDB servers starting with the 3.4 release.
• Zlib: Zlib compression can be used when connecting to MongoDB servers starting with the 3.6 release.

The driver will negotiate which, if any, compression algorithm is used based on capabilities advertised by the server in the ismaster command response.

Specify compression via MongoClientURI

import com.mongodb.MongoClientURI;
import com.mongodb.MongoClient;

To specify compression with MongoClientURI, specify compressors as part of the connection string, as in:

MongoClientURI uri = new MongoClientURI("mongodb://localhost/?compressors=snappy");
MongoClient mongoClient = new MongoClient(uri);

for Snappy compression, or

MongoClientURI uri = new MongoClientURI("mongodb://localhost/?compressors=zlib");
MongoClient mongoClient = new MongoClient(uri);

for zlib compression, or

MongoClientURI uri = new MongoClientURI("mongodb://localhost/?compressors=snappy,zlib");
MongoClient mongoClient = new MongoClient(uri);

to configure multiple compressors.

In all cases the driver will use the first compressor in the list for which the server advertises support.

Specify compression via MongoClientOptions

import com.mongodb.MongoClientOptions;
import com.mongodb.MongoCompressor;
import java.util.Arrays;

To specify compression with MongoClientOptions, set the compressors property to a list of MongoCompressor instances:

 MongoClientOptions options = MongoClientOptions.builder()
                                                .compressorList(Arrays.asList(MongoCompressor.createSnappyCompressor()))
                                                .build();
 MongoClient client = new MongoClient("localhost", options);

for Snappy compression, or

 MongoClientOptions options = MongoClientOptions.builder()
                                                .compressorList(Arrays.asList(MongoCompressor.createZlibCompressor()))
                                                .build();
 MongoClient client = new MongoClient("localhost", options);

for zlib compression, or

 MongoClientOptions options = MongoClientOptions.builder()
                                                .compressorList(Arrays.asList(MongoCompressor.createSnappyCompressor(), 
                                                                              MongoCompressor.createZlibCompressor()))
                                                .build();
 MongoClient client = new MongoClient("localhost", options);

to configure multiple compressors.

As with configuration with a URI, the driver will use the first compressor in the list for which the server advertises support.

Dependencies

As the JDK has no built-in support for Snappy, the driver takes a dependency on an existing open-source Snappy implementation. See the snappy-java Github repository for details.