Network Compression

PyMongo supports network compression where network traffic between the client and MongoDB server are compressed which reduces the amount of data passed over the network. By default no compression is used.

The driver supports the following algorithms:

  • snappy available in MongoDB 3.4 and later.

  • zlib available in MongoDB 3.6 and later.

  • zstandard available in MongoDB 4.2 and later.


snappy and zstandard compression require additional dependencies. See Optional dependencies.

Applications can enable wire protocol compression via the compressors URI and keyword argument to MongoClient(). For example:

>>> client = MongoClient(compressors='zlib')

When multiple compression algorithms are given, the driver selects the first one in the list supported by the MongoDB instance to which it is connected. For example:

>>> client = MongoClient(compressors='snappy,zstandard,zlib')

The compressors option can also be set via the URI:

>>> client = MongoClient('mongodb://,zstandard,zlib')

Additionally, zlib compression allows specifying a compression level with supported values from -1 to 9:

>>> client = MongoClient(compressors='zlib', zlibCompressionLevel=-1)

The zlibCompressionLevel is passed as the level argument to zlib.compress().

See also

The MongoDB documentation on network compression URI options.