IDSelectorNot causing "segmentation fault" when calling search()

[plurch]

Summary

I am getting a "segmentation fault" error which is crashing the python interpreter when using IDSelectorNot to exclude some IDs from the search() results. See below for a script to reproduce the issue.

Please let me know if I am doing something incorrectly - thanks!

Platform

OS: macOS 13.5 (Ventura) / Apple Silicon

Faiss version: 1.7.4

Installed from: conda / python 3.11

Faiss compilation options: n/a

Running on:

• CPU
• GPU

Interface:

• C++
• Python

Reproduction instructions

import faiss
import numpy as np

print(f'faiss version: {faiss.__version__}')

vecs = np.random.rand(10000, 50).astype(np.float32)
vecs_normalized = np.copy(vecs)
faiss.normalize_L2(vecs_normalized)

index_faiss = faiss.IndexHNSWFlat(vecs_normalized.shape[1], 32, faiss.METRIC_INNER_PRODUCT)
index_faiss.add(vecs_normalized)

query_vec = vecs_normalized[0].reshape(1, -1)
top_k = 20

# this works fine
cos_sims, idx_results = index_faiss.search(query_vec, top_k)
print(f'base idx_results: {idx_results}')

# this also works fine
params_include = faiss.SearchParametersHNSW(sel = faiss.IDSelectorBatch([3195, 1935]))
cos_sims, idx_results = index_faiss.search(query_vec, top_k, params=params_include)
print(f'params_include idx_results: {idx_results}')

# Error: "segmentation fault" when calling search()
params_exclude = faiss.SearchParametersHNSW(sel = faiss.IDSelectorNot(faiss.IDSelectorBatch([3195, 1935])))
cos_sims, idx_results = index_faiss.search(query_vec, top_k, params=params_exclude)
print(f'params_exclude idx_results: {idx_results}')

[mdouze]

I can repro, it's an object ownership bug. Will fix. In the meantime to work around it, do

sel1 = faiss.IDSelectorBatch([3195, 1935])
sel2 = faiss.IDSelectorNot(sel1)
params_exclude = faiss.SearchParametersHNSW(sel = sel2)
cos_sims, idx_results = index_faiss.search(query_vec, top_k, params=params_exclude)
print(f'params_exclude idx_results: {idx_results}')

[plurch]

Thanks for the quick response and workaround solution! I tested the workaround and it works as expected without an error. 👍

[mdouze]

Was fixed in current version