KNN Compare: Manticore vs FAISS vs HNSWlib

Requirements

• macOS (Homebrew) or Linux
• Manticore running locally on 127.0.0.1:9306
• Manticore t table containing columns:
  • id (integer)
  • vec (vector as string, e.g. [0.1, 0.2, ...])
• Build tools: C++ compiler + CMake 3.24+ (for FAISS submodule)
• Dependencies: MySQL client headers, OpenMP (macOS), BLAS/LAPACK (Linux)
• Submodules: faiss, hnswlib

Install dependencies

macOS (Homebrew)

brew install mysql-client libomp
git submodule update --init --recursive

Linux

Ubuntu/Debian:

sudo apt-get update
sudo apt-get install -y build-essential cmake libmysqlclient-dev libopenblas-dev liblapack-dev
git submodule update --init --recursive

RHEL:

sudo dnf install cmake gcc-c++ mysql-devel openblas-devel lapack-devel
git submodule update --init --recursive

Optional: use a system FAISS package instead of the submodule:

make FAISS_PREFIX=/usr/local FAISS_DIR=

Build

make

The first build compiles the FAISS submodule into faiss/build.

On macOS, BLAS/LAPACK comes from Accelerate and OpenMP comes from libomp.

FAISS builds in Release mode and auto-selects SIMD (avx512, avx2, or generic) based on your CPU. Override if needed:

make FAISS_OPT_LEVEL=generic

Verbose FAISS build output:

make FAISS_VERBOSE=1

If you see linker errors like undefined reference to __kmpc_fork_call, rebuild FAISS with the same compiler as the demo (e.g., make CXX=g++ or make CXX=clang++), and delete faiss/build before retrying.

Clean build artifacts and cached indexes:

make clean

Clear cached indexes before running:

./knn_compare --clear

Run

./knn_compare

Optional:

./knn_compare -k 10

./knn_compare -k 10 -ef 64 -efc 200

./knn_compare -metric l2 -k 10 -ef 64 -efc 200

The program caches indexes to index_hnsw_<metric>_efc<efc>.faiss, index_flat_<metric>_efc<efc>.faiss, and index_hnswlib_<metric>_efc<efc>.bin in the working directory to avoid rebuilding on subsequent runs.