Indexes
This is OmniGraph-specific (not Lance):
L1 — Lance index types OmniGraph exposes
| Index | Use | Notes |
|---|---|---|
| BTREE scalar | range / equality on any scalar | created on @key, @index(...), and on key columns by ensure_indices() |
| Inverted (FTS) | search, fuzzy, match_text, bm25 | created on text columns referenced by FTS queries |
| Vector | nearest() k-NN | Lance picks IVF_PQ vs HNSW family by configuration; OmniGraph stores as FixedSizeList(Float32, dim) |
L2 — OmniGraph orchestration
ensure_indices()/ensure_indices_on(branch)— idempotent build of BTREE + inverted indexes for the current head; safe to re-run.- Indexes are built on the branch head (not on a snapshot), so reads always see the current index state.
- Lazy branch forking for indexes: a branch that hasn't mutated a sub-table doesn't need its own index — the main lineage's index is reused until the first write triggers a copy-on-write fork.
- Vector index parameters (metric, nlist, nprobe, etc.) are not exposed in the schema; they default at the Lance layer and are picked up automatically when an index is asked for on a Vector column.
L2 — Graph topology index (graph_index/mod.rs)
This is OmniGraph-specific (not Lance):
TypeIndex: denseu32 ↔ String idmapping per node type.CsrIndex: Compressed Sparse Row representation of edges per edge type —offsets[i]..offsets[i+1]slices intotargets.GraphIndex { type_indices, csr (out), csc (in) }— built on demand from a snapshot's edge tables, lazily: only when anExpandthe planner routes to the CSR path (dense / large frontier) or anAntiJoinactually needs it.- Cached in
RuntimeCache::graph_indices(LRU, max 8 entries, keyed by snapshot id + edge table versions). - Selective
Expands resolve neighbors from the persistedsrc/dstBTREE instead (one indexed scan per hop) and never trigger the CSR build; see query-language → Expand. Pure scans, and queries served entirely by the indexed traversal path, skip it.