diskann-garnet

This crate provides an implementation of DataProvider for Garnet as well as FFI endpoints for Garnet to access DiskANN functionality. Garnet is a remote cache service developed by Microsoft Research with Redis compatibility, and has better performance, throughput, and lower latency than competitors. With this crate, it also supports vector sets, allowing clients to use vector sets for ANN indexing and search.

Supported Features

diskann-garnet currently supports vectors with element types of 32-bit float and 8-bit signed or unsigned integers. Indexes can be full precision or quantized. When the index is quantized, the full precision vectors are still stored in order to rerank the final candidates during search operations, which improves recall.

In addition to the normal vector set operations, the following extensions are added:

New Element Types

• XI8: signed 8-bit integers
• XU8: unsigned 8-bit integers

Distance Metrics

Redis always uses cosine distance, but many vector data sets use other metrics. The following metrics can be used by passing XDISTANCE_METRIC <metric> options to the VADD command. The default is L2.

• COSINE
• XCOSINE_NORMALIZED
• IP (inner product)
• L2 (euclidean)

New Quantizers

• XNOQUANT_I8: full precision 8-bit signed integer
• XNOQUANT_U8: full precision 8-bit unsigned integer
• XBIN_I8: binary quantization of 8-bit signed integer (using DiskANN's spherical quantizer based on RaBitQ)
• XBIN_U8: binary quantization of 8-bit unsigned integer (using DiskANN's spherical quantizer based on RaBitQ)

Currently there is a limit of 2^32 - 1 vectors in a single instance due to internal IDs being u32. This restriction will be lifted in the future.

Installing

Garnet depends on diskann-garnet as a NuGet package, which means you can simply check out the Garnet repo on Windows or Linux, and if you have a dotnet toolchain installed you can just run:

dotnet run -c Release -f net10.0 --project main/GarnetServer -- --enable-vector-set-preview

and it will build and launch Garnet with vector sets enabled.

Local Installs

If you want to install a specific version of diskann-garnet to use with Garnet, it is a little more complicated. Aside from compiling diskann-garnet, you will need to create a NuGet package. For example:

cd diskann-garnet
cargo build --release
mkdir ../target/pkg
mkdir ../target/pkg/linux
mkdir ../target/pkg/windows
mkdir ../target/pkg/docs
cp diskann-garnet.nuspec ../target/pkg
cp README.md ../target/pkg/linux/libdiskann_garnet.so # dummy file
cp ../target/release/*.dll ../target/pkg/windows
cp ../target/release/*.pdb ../target/pkg/windows
cp README.md ../target/pkg/docs
nuget pack -BasePath ../target/pkg -OutputDirectory LOCAL_NUGET_PATH
nuget locals all -clear

You will need to set up a local path to host NuGets and setup %APPDATA%/NuGet/NuGet.config appropriately. For example:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <packageSources>
    <add key="local" value="LOCAL_NUGET_PATH" />
    <add key="nuget.org" value="https://api.nuget.org/v3/index.json" protocolVersion="3" />
  </packageSources>
  <packageSourceMapping>
    <packageSource key="nuget.org">
        <package pattern="*"/>
    </packageSource>
    <packageSource key="local">
        <package pattern="diskann-garnet"/>
    </packageSource> 
  </packageSourceMapping>
</configuration>

Replace LOCAL_NUGET_PATH with whatever path you like.

Linux instructions are a bit more difficult as nuget pack does not exist in Linux. You will need to grab an existing NuGet from NuGet.org, unzip it, and then replace the files, and rezip.

mkdir target/nupkg
cd target/nupkg
unzip PATH_TO/diskann-garnet.x.y.z.nupkg
cd ../..
cargo build --release --package diskann-garnet
cp diskann-garnet/diskann-garnet.nuspec target/nupkg/
cp target/release/libdiskann_garnet.so target/nupkg/runtimes/linux-x64/native/
cd target/nupkg
zip -r LOCAL_NUGET_PATH/diskann-garnet.X.Y.Z.nupkg *
dotnet nuget locals all --clear

Replace LOCAL_NUGET_PATH with the path you like and X.Y.Z with the version number from diskann-garnet.nuspec.

If you aren't replacing the same version of diskann-garnet as Garnet is using, you can modify Garnet's Directory.Packages.props file to set the version to the one you want.

Testing

Unit tests are run in the usual way with cargo test, but many are end-to-end and run from the Garnet side. These two invocations will run the relevant tests:

dotnet test test/standalone/Garnet.test.vectorset -f net10.0 -c Debug --filter RespVectorSetTests
dotnet test test/standalone/Garnet.test.extensions -f net10.0 -c Debug --filter DiskANNServiceTests

Client Examples

To benchmark or see an example of usage, see the vectorset crate, which uses the official Redis Rust client to run vector workloads on Garnet.