DiskANN's delete repair only fixes forward edges (nodes the deleted
node pointed to). Stale reverse edges can cause deleted rowids to
appear in search results. Fix: track a 'confirmed' flag on each
search candidate, set when the full-precision vector is successfully
read during re-ranking. Only confirmed candidates are included in
output. Zero additional SQL queries — piggybacks on the existing
re-rank vector read.
Also adds delete hardening tests:
- Rescore: interleaved delete+KNN, rowid_in after deletes, full
delete+reinsert cycle
- DiskANN: delete+reinsert cycles with KNN verification, interleaved
delete+KNN
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
sqlite3_column_blob() returns NULL for zero-length blobs or on OOM.
Several call sites in rescore KNN and DiskANN node/vector read passed
the result directly to memcpy without checking, risking NULL deref on
corrupt or empty databases. IVF already had proper NULL checks.
Adds corruption regression tests that truncate shadow table blobs and
verify the query errors cleanly instead of crashing.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
vec0Update_UpdateVectorColumn writes to flat chunk blobs but does not
update DiskANN graph or IVF index structures, silently corrupting KNN
results. Now returns a clear error for these index types. Rescore
UPDATE is unaffected — it already has a full implementation that
updates both quantized chunks and float vectors.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Add DiskANN graph-based index: builds a Vamana graph with configurable R
(max degree) and L (search list size, separate for insert/query), supports
int8 quantization with rescore, lazy reverse-edge replacement, pre-quantized
query optimization, and insert buffer reuse. Includes shadow table management,
delete support, KNN integration, compile flag (SQLITE_VEC_ENABLE_DISKANN),
release-demo workflow, fuzz targets, and tests. Fixes rescore int8
quantization bug.
