The Scala driver supports compression of messages to and from MongoDB servers. The driver implements the three algorithms that are supported by MongoDB servers:
Snappy: Snappy compression can be used when connecting to MongoDB servers running version 3.4 and later.
Zlib: Zlib compression can be used when connecting to MongoDB servers running version 3.6 and later.
Zstandard: Zstandard compression can be used when connecting to MongoDB servers running version 4.2 and later.
The driver will negotiate which, if any, compression algorithm is used
based on capabilities advertised by the server in the hello command
response.
Specify Compression By Using ConnectionString
Include the following import statements:
import org.mongodb.scala._
To specify compression within a ConnectionString, specify
compressors as part of the connection string.
The following code specifies the Snappy compression algorithm:
val mongoClient: MongoClient = MongoClient("mongodb://localhost/?compressors=snappy")
The following code specifies the Zlib compression algorithm:
val mongoClient: MongoClient = MongoClient("mongodb://localhost/?compressors=zlib")
The following code specifies the Zstandard compression algorithm:
val mongoClient: MongoClient = MongoClient("mongodb://localhost/?compressors=zstd")
The following code specifies multiple compression algorithms:
val mongoClient: MongoClient = MongoClient("mongodb://localhost/?compressors=snappy,zlib,zstd")
In all cases, the driver uses the first compressor in the list for which the server has support.
Specify Compression By Using MongoClientSettings
Include the following import statements:
import org.mongodb.scala._ import scala.collection.JavaConverters._
To specify compression within a MongoClientSettings instance, set the compressors
property to a list of MongoCompressor instances.
The following code specifies the Snappy compression algorithm:
val settings = MongoClientSettings.builder() .compressorList(List(MongoCompressor.createSnappyCompressor).asJava) .build() val client = MongoClient(settings)
The following code specifies the Zlib compression algorithm:
val settings = MongoClientSettings.builder() .compressorList(List(MongoCompressor.createZlibCompressor).asJava) .build() val client = MongoClient(settings)
The following code specifies the Zstandard compression algorithm:
val settings = MongoClientSettings.builder() .compressorList(List(MongoCompressor.createZstdCompressor).asJava) .build() val client = MongoClient(settings)
The following code specifies multiple compression algorithms:
val settings = MongoClientSettings.builder() .compressorList(List(MongoCompressor.createSnappyCompressor, MongoCompressor.createZlibCompressor, MongoCompressor.createZstdCompressor).asJava) .build() val client = MongoClient(settings)
As with configuration that uses the connection string, the driver uses the first compressor in the list for which the server has support.
Dependencies
As the JDK has no built-in support for Snappy or Zstandard, the driver takes a dependency on existing open-source Snappy and Zstandard implementations. See the snappy-java GitHub repository and the zstd-java GitHub repository for details.