Segmented Code Adjustment Quantization (SAQ)

[SIGMOD 2026] SAQ: Pushing the Limits of Vector Quantization through Code Adjustment and Dimension Segmentation. arxiv

The fastest and most accurate quantization method for high-dimensional vectors.

Our project introduces Segmented Code Adjustment Quantization (SAQ), a novel quantization algorithm built upon dimension balancing techniques and dimension reduction techniques. This advancement enables compression of high-dimensional vectors at arbitrary compression rates while maintaining quantization and estimation simplicity identical to classical scalar quantization. Notably, Segmented CAQ (SAQ) delivers superior accuracy at equivalent compression rates and efficient quantization process (80x faster than RaBitQ).

Here are some results of SAQ on the Msmarco dataset with 1024 dimensions and 10 million vectors.

Preparing

Prerequisites

• AVX512 is required
• Install dependencies:

apt install libfmt-dev libgoogle-glog-dev libgflags-dev libgtest-dev

Compiling

mkdir build bin
cd ./build
cmake ..
make

Source codes are stored in ./src, binary files are stored in ./bin.

Datasets

Download and preprocess the datasets. Detailed instructions can be found in ./data/README.md. Please build the IVF index and PCA matrix before running SAQ.

Running

Unit Test

The unit test of SAQ and CAQ can be found in the ./unit_test directory. You can run the tests using ctest in ./build/ or directly execute the test binaries ./bin/unit_tests.

Creating index

./bin/create_index -dataset gist -B 4     # SAQ
./bin/create_index -dataset gist -B 4 -enable_segmentation=false     #for CAQ only

• -dataset gist for the name of dataset
• -B 4 for average number of bits used in SAQ per dimension, which can be a float number (e.g., 0.5, 1.5, 4, 8).
• -enable_segmentation=false to disable segmentation, that is, CAQ only.

The quantized index are stored in ./data/gist/.

Test quantization accuracy

./bin/test_relative_error -dataset gist -B 4    # SAQ
./bin/test_relative_error -dataset gist -B 4 -enable_segmentation=false     #for CAQ only

• The result files are stored in ./results/saq/
• Raw datasets are required to compute quantization error.

Test query performance

./bin/test_qps -dataset gist -B 4 # SAQ
./bin/test_qps -dataset gist -B 4 -enable_segmentation=false  #for CAQ only

• The result files are stored in ./results/saq/
• Note: currently in the test code, we compute the average distance ratio so the raw datasets are loaded in memory.

For more arguments, please refer to ./bin/create_index --help.