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Compression

  • concept
March 16, 2025
+ 12
In response to increasing volumes of data being sent over the wire, Couchbase Data Platform provides data compression between the SDK and Couchbase Server.

From version 3.5.2, the .NET SDK provides compression by using Snappier, a performance-focused C# port of Snappy. This was previously opt-in only via installing the corresponding Couchbase.Extensions package.

Overview

Documents may already be stored compressed with Snappy on the server. New documents may be passed from client applications to the server in compressed form, saving around 40% in bandwidth (depending on the document content and size), and also transmission time. Register a Snappy plugin for the SDK to use compression for requests and responses, using the WithSnappyCompression() extension method, then these operations take place automatically after the SDK negotiates the capability with the server.

For SDKs with Snappy compression enabled, documents will be automatically compressed if compression is not turned Off in Couchbase Server (see below).

Usage and Customization

Starting with .NET SDK v3.5.2, Snappier compression is enabled in the ClusterOptions using the WithSnappyCompression() extension method.

You can disable compression or customize certain settings, both via ClusterOptions or Connection String parameters:

csharp
Copy
// ConnectionString parameters
var connectionString = "couchbases://cb.<your-endpoint>.cloud.couchbase.com:18091?compression=true&compression_min_size=512&compression_min_ratio=0.82";
// for development on local cluster, use: couchbase://localhost:8091

// ClusterOptions parameters
var clusterOptions = new ClusterOptions
{
    Compression = true,
    CompressionMinRatio = 0.82f, // Float value between 1 and 0.
    CompressionMinSize = 512 // Integer value represented in bytes.
}.WithSnappyCompression();

// Connect
clusterOptions.WithConnectionString(connectionString);
clusterOptions.WithCredentials("Administrator", "password");

var cluster = await Cluster.ConnectAsync(clusterOptions).ConfigureAwait(false);

Please refer to the API Documentation for details on CompressionMinRatio and CompressionMinSize.

Advanced: Bring Your Own Compression

You can provide the SDK with your own implementation of Snappy compression/decompression by implementing the ICompressionAlgorithm interface, and passing it through your ClusterOptions with:

csharp
Copy
clusterOptions.WithCompressionAlgorithm(myCompressionImplementation);

// See Couchbase.Compression.Snappier.Internal.SnappierCompression for details on how Snappier implements the interface.

Even when compression is turned Off server-side, Couchbase Server will decompress documents in memory, and store them recompressed on disk (using Snappy) see server compression docs.

It is therefore not recommended to implement a different compression algorithm from Snappy as this may very well cause data corruption.

Limits

The document must be below 20MiB in size in both compressed and uncompressed form. Compression is available in Couchbase Capella, and in the Enterprise Edition of self-managed Couchbase Server.

This size limit is enforced by Couchbase Server; in practice it will affect very few users, as most JSON documents are considerably smaller. A compressed doument of just under 20MB, which is greater than 20,971,520 bytes (20 MiB) when uncompressed, will be rejected by the server as follows:

  • Couchbase Server decompresses the document to check that it is valid JSON, and is correctly compressed with Snappy, and at this point measures it against max data size (20 MiB).

  • If the decompressed value’s size exceeds this limit, the mutation is failed with a "too big" error code (E2BIG code 3).

Therefore, where necessary, enforce document size limits in your application on uncompressed documents.

Operating Modes (Server-side)

The three modes in which compression can be used — "off", "passive", and "active" — are configured per bucket in the configuration settings on the cluster.

Table 1. Compression Operating Modes
OFF PASSIVE ACTIVE

Negotiating SNAPPY

ignore

acknowledge

acknowledge

Sending compressed data when SNAPPY feature enabled

-

accept

accept

Sending compressed data when SNAPPY feature disabled

reject as invalid

reject as invalid

reject as invalid

Receiving data which were previously compressed on the server

server inflates and sends plain data

server sends compressed data

server sends compressed data

Receiving data which were not previously compressed on the server

server sends plain data

server sends plain data

server might send compressed data (the compression is done in the background on the server)

Compression for .NET SDK 3.4.10 to 3.5.1

Snappier is integrated with the .NET Couchbase.Extensions Library. Since .NET SDK 3.4.10, the .NET SDK has been able to work with external Snappy libraries as the setting for the Server flag SnappyEverywhere is now supported.

Install Snappier with the .NET Couchbase.Extensions Library.