What types of quantization does Qdrant support?

Qdrant supports three quantization methods: scalar, product, and binary. Scalar quantization compresses float32 dimensions to int8, giving 4x memory reduction with minimal recall loss and is the recommended default. Product quantization compresses groups of dimensions using learned codebooks, giving up to 64x reduction at higher recall cost. Binary quantization stores one bit per dimension, giving 32x reduction and enabling fast Hamming distance, best for high-dimensional normalized embeddings. All three support a rescoring step that uses full-precision vectors on top candidates.