Compression Configuration

cshelve supports compression to reduce the size of stored data. This is particularly useful when working with large datasets or to reduce network time. The compression algorithm can be configured using a configuration file.

Configuration File

The compression settings are specified in an INI file. Below is an example configuration file named config.ini:

[default]
provider        = in-memory
persist-key     = compression
exists          = true

[compression]
algorithm   = zlib
level       = 1

In this example, the algorithm is set to zlib, and the compression level is set to 1.

Supported Algorithms

Currently, cshelve supports the following compression algorithms:

• zlib: A widely-used compression library.

Using Compression

Once compression is configured as previously in the config.ini file, it will automatically compress data before storing it and decompress data when retrieving it. The application code doesn’t need to be updated:

import cshelve

with cshelve.open('config.ini') as db:
    db['data'] = 'This is some data that will be compressed.'

with cshelve.open('config.ini') as db:
    data = db['data']
    print(data)  # Output: This is some data that will be compressed.

In this example, the data is compressed before being stored and decompressed when retrieved, thanks to the configuration.

Error Handling

If an unsupported compression algorithm is specified, cshelve will raise an UnknownCompressionAlgorithmError. Ensure that the algorithm specified in the configuration file is supported.