Compress Network Traffic

Version Compatibility

All versions of the Kotlin Sync driver support Snappy, Zlib, and Zstandard compression.

The following table lists the minimum supported MongoDB Server version for each algorithm:

Compression Algorithm	Minimum Server Version
Snappy	4.2
Zlib	4.2
Zstandard	4.2

Enable Network Compression

To enable network compression for your MongoDB connection, install the required dependencies and specify the compression algorithms that you want to use.

Install Dependencies

The following table lists each algorithm and the dependency it requires, if any:

Compression Algorithm	Dependency
Snappy	Download `snappy-java`, a Java JNI wrapper for the Snappy library. To install, see snappy-java in Maven Central.
Zlib	None. The driver natively supports Zlib compression.
Zstandard	Download `zstd-jni`, a Java JNI wrapper for the Zstandard library. To install, see zstd-jni in Maven Central.

Specify Compression Algorithms

You can enable compression for the connection to your MongoDB instance by specifying the algorithms in one of the following ways:

Chain the compressorList() method to the MongoClientSettings.builder() method.
Use the compressors parameter in your connection URI.

The following examples demonstrate how to specify all available compressors while connecting to MongoDB. Select the MongoClientSettings or Connection URI tab to see the corresponding syntax:

val settings = MongoClientSettings.builder()
    .applyConnectionString(ConnectionString("<connection string>"))
    .compressorList(
        listOf(
            MongoCompressor.createSnappyCompressor(),
            MongoCompressor.createZlibCompressor(),
            MongoCompressor.createZstdCompressor())
    )
    .build()
val mongoClient = MongoClient.create(settings)

val uri = ConnectionString("mongodb+srv://<db_username>:<db_password>@<cluster-url>/?compressors=snappy,zlib,zstd")
val mongoClient = MongoClient.create(uri)

Specify the Zlib Compression Level

If you specify Zlib as one of your compression algorithms, you can also use the MongoCompressor.LEVEL property to specify a compression level. This option accepts an integer value between -1 and 9:

-1: Default compression (usually 6)
0: No compression
1: Fastest speed but lowest compression
9: Best compression but slowest speed

The following examples demonstrate how to specify a compression level for the zlib compressor. Select the MongoClientSettings or Connection URI tab to see the corresponding syntax:

val zlib = MongoCompressor.createZlibCompressor()
val settings = MongoClientSettings.builder()
    .applyConnectionString(ConnectionString(uri))
    .compressorList(listOf(zlib.withProperty(MongoCompressor.LEVEL, <level>)))
    .build()
val mongoClient = MongoClient.create(settings)

val uri = "mongodb://<db_username>:<db_password>@<hostname>:<port>/?" +
          "compressors=zlib" +
          "zlibCompressionLevel=<zlib compression level>"
val mongoClient = MongoClient.create(uri)

API Documentation

To learn more about any of the methods or types discussed in this guide, see the following API documentation:

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Connection Options

Server Selection