59d7dadc18
2 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
jordan
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8aa1fbb414 |
vector search: normalize the query, instrument the blob path, expose per-group vector counts
Three real defects, plus a retracted fourth that was a probe artifact. P3 (fixed) - query/stored normalization asymmetry. The write path L2-normalized every stored vector; the read path passed the caller's raw query straight to the index, so the two sides lived in different spaces. With unit v, d = |q|^2 - 2q.v + 1, so a non-unit query shifted and scaled every distance by |q|^2. Measured live: 591-1174 against a documented [0,4], and an exact match scoring |q|^2 - 1 instead of ~0. vector_search_items now normalizes with the canonical l2_normalize; a zero-norm query (no direction, so nearest-by-cosine is undefined) is rejected with 400. Ranking is unchanged - |q|^2 and 1 are constant across candidates - which is why it went unnoticed; what broke was every absolute use of the number. WIRE-VISIBLE, recorded in CHANGELOG. P2 (fixed) - the blob path had zero instrumentation. Added per-kind tidaldb_cluster_blobs_originated/applied/apply_failed totals. Label cardinality is fixed at 4 by construction via a new BlobKind enum, and BlobRecord::blob_kind is now the ONE exhaustive match over the variants (kind() derives from it), so a new variant is a compile error in one place instead of a silent zero in three. Only the live apply path is counted - boot replay would inflate applied past originated on every restart. Coverage gap (fixed) - tidaldb_usearch_vector_count rendered only the metrics owner's shard group, so on a 3-group node two thirds of the corpus had no vector-count series at all. Co-located groups now render shard="N"; the owner stays unlabeled for wire compatibility, so an alert grouped by (shard) buckets each replica set separately without double-counting. P1 (RETRACTED) - the "replica-divergent vector index" does not exist. Every probe wrote through the /sharded/ surface, which hash-partitions and applies to the owning region's local store with no WAL append, and therefore does not replicate BY DESIGN (cluster/node.rs:8828-8829). A controlled A/B settled it: on /items plus /embeddings all 6 entities reach all 3 replicas; on the sharded surface four of six reach exactly one node. Both are now pinned by tests. See tmp/vector-search-correctness/diagnosis.md and the k3s-fleet cluster-state.yaml entry RETRACTED_blob_replication_rf1_2026_08_30. Pre-work: usearch_index.rs 872 to 503 lines by extracting its tests to a sibling (the project's existing path-attribute convention), and the three hand-rolled l2_normalize copies collapsed to one. The two entity copies used a zero threshold about 2900x looser than the canonical one; normalize_centroid now names the centroid zero-tolerance policy once, and a test pins the tightened behavior. Tests: 2107 lib (+5), 8 vector_search e2e (+4, three of which fail without the P3 fix), 4 cluster_sharding e2e (+2). The heavy multiproc tests in cluster_sharding are now serialized - four concurrent 3-node clusters made the pre-existing failover test miss its 10s budget. |
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jx12n
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44b768b8c6 |
feat(m11): sharding × replication + rebalancing (m11p6 L3-L5)
End the "replicated XOR sharded" split: S shard groups, each a
replication group at RF with its own elected leader, leaders balanced
across nodes; any gateway hash-routes.
- One unified write surface: /items,/embeddings,/signals hash-route to
the owning shard group's leader (ShardRouter FNV-1a) AND replicate at
RF. x-tidal-ack/x-tidal-seq, quorum await, NotLeader/QuorumTimeout are
per-group; NotLeader names the group.
- Rebalance verbs (L3): POST /cluster/shards/{id}/transfer (fenced
leadership move) + /cluster/shards/{id}/replicas (add/remove replica).
A ?shard= selector threads through every per-shard admin verb and is
propagated on intra-group forwards (ShardReplica::admin_path). S=1 is
byte-for-byte (no selector, no shard in NotLeader body).
- Tier-3 exit gate (cluster_sharding.rs): 3 nodes × 3 shards × RF=3 over
real OS processes — SIGKILL a node under ack=quorum load → only its
shard-leaderships re-elect, reads never stop, zero acked loss across
random kill points; plus a rebalance-verb test. Harness:
MultiProcCluster::start_sharded.
- tidal-stress drives the single path (WritePath::Leader|Sharded gone),
spreading writes round-robin across gateways or pinning --leader-url.
- Throughput: local 3×3 sustains 3,000 quorum signal-writes/s @ 0% err,
~30% CPU, lag ~0 (generator-bound). ≥5,000/s + ≥2.5× scaling is Ref-A.
Known follow-up (tracked): per-group-aware node readiness and cross-node
read fan-out under PARTIAL placement.
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