Summary:
Pull Request resolved: https://github.com/facebookresearch/faiss/pull/5234
There are two VisitedTable implementations. Avoid runtime checks between the two by making them separate classes and templatizing the visited tables on them.
Reviewed By: mnorris11
Differential Revision: D105961848
fbshipit-source-id: 8c82c4ba2cf13e221a4f6a4e534f49e58073355d
Summary:
Pull Request resolved: https://github.com/facebookresearch/faiss/pull/5063
Fix two bugs in `fbcode/faiss/impl/NSG.cpp`:
**Bug 1: `init_ids[i]` → `init_ids[num_ids]` in `search_on_graph`**
The init loop in `search_on_graph` reads neighbors of the enterpoint from the
knn_graph. When an entry has `id >= ntotal`, it is skipped via `continue`. The
loop variable `i` advances but `num_ids` (the write pointer) does not. The old
code wrote `init_ids[i] = id`, placing valid entries at non-contiguous positions
and leaving gaps in between. The gap-filling loop that follows starts from
`num_ids`, so it never overwrites the internal gaps.
Example with neighbors `[5, 99999, 3, 99999, 7]` and `ntotal=100`:
| i | id | old: `init_ids[i]=id` | new: `init_ids[num_ids]=id` |
|---|-------|-----------------------|-----------------------------|
| 0 | 5 | `init_ids[0] = 5` | `init_ids[0] = 5` |
| 1 | 99999 | skip (gap at [1]) | skip |
| 2 | 3 | `init_ids[2] = 3` | `init_ids[1] = 3` |
| 3 | 99999 | skip (gap at [3]) | skip |
| 4 | 7 | `init_ids[4] = 7` | `init_ids[2] = 7` |
Old result: `[5, 0, 3, 0, 7, ...]` — gaps contain 0 (from `vector<int>`
zero-initialization). The consumption loop reads these zeros as node IDs,
biasing the search pool toward node 0 during graph construction and degrading
graph quality.
Fixed result: `[5, 3, 7, ...]` — valid entries packed contiguously, gap-filling
starts from the correct position.
**Bug 2: `sync_prune` out-of-bounds access**
`sync_prune` accesses `pool[start]` without bounds checking. Two cases cause
out-of-bounds reads:
- Pool is empty after augmentation
- Pool contains only the query node itself (e.g., `ntotal=1`)
In both cases `start` advances past `pool.size()` and `pool[start]` is an
out-of-bounds vector read — undefined behavior that crashes under ASAN and
silently corrupts the graph in release builds.
Trace for `ntotal=1, L=1`:
1. `search_on_graph` returns `pool = [{id:0, dist:0}]`
2. `sync_prune(q=0)`: `pool[0].id == q` → `start++` → `start=1 == pool.size()`
3. Old code: `result.push_back(pool[1])` — OOB read
4. Fix: guard checks `start >= pool.size()`, fills graph row with `EMPTY_ID`
**Other fixes:**
- Replace `min = 1e6` (float-to-int truncation) with `std::numeric_limits<int>::max()`
- Remove `srand(0x1998)` from the NSG constructor (global RNG side effect)
Reviewed By: mnorris11
Differential Revision: D100024850
fbshipit-source-id: 0d290801658e381e198b6c6ab54ebe981e0f09f3
Summary:
- Fix compiler warnings in all 20 FAISS C++ test files
- Fixes include `-Wshadow`, `-Wunused-parameter`, and signed/unsigned comparisons
All changes are mechanical. No functional changes.
Part 13/13 of the compiler warnings cleanup (split from https://github.com/facebookresearch/faiss/issues/4810 per maintainer request).
Pull Request resolved: https://github.com/facebookresearch/faiss/pull/4944
Test Plan:
- [x] No functional changes — all fixes are mechanical renames and annotations
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>
Reviewed By: mnorris11
Differential Revision: D96996609
Pulled By: alibeklfc
fbshipit-source-id: 72555246a4ccf540eb5422e64018c8d5e2660dce
Summary:
Pull Request resolved: https://github.com/facebookresearch/faiss/pull/3975
Graph-based indices are often quite bulky in terms of storage becausee the out-degree of the edges is high (32 or more) and edges are just encoded as 32-bit ints.
This diff makes it possible to replace the graph structure of NSG with a compressed version, but only for search (the full graph needs to be present at addition time).
It is easier to do it for NSG than for HNSW for several reasons:
- NSG's graph is not hierarichal -- HNSW is and the edges for the different levels are interleaved
- the NSG graph object is already isolated well (thanks KingLittleQ!)
- NSG cannot be built incrementally so it is easier to convert the graph after all adds are done in one go.
The custom compressed graph is currently only implemented as a test, but could be integrated in the main Faiss as an option to NSG.
Reviewed By: algoriddle
Differential Revision: D64646137
fbshipit-source-id: c10c2a485b44561d32941ce1e7a0e3fe512cf0ac
Matthijs Douze