Turso Indexing Capabilities & All-TursoDB Persistence Audit (2026)

This document evaluates tursodatabase/turso (turso = 0.6.1) indexing capabilities across composite covering B-tree indexes, partial indexes (WHERE ...), native Full-Text Search (USING fts), vector similarity indexing, and MVCC concurrency, cross-referenced against the 118 tables and 131 indexes in crates/vox-db. It also presents a complete workspace persistence audit classifying all 17 storage and index surfaces into three categories: canonical TursoDB stores, sidecar JSON/external stores to migrate into TursoDB (vox-db), and documented positive-tradeoff exceptions (tantivy derived lexical index, sqlx user-app Postgres/MySQL runtime, dev-only rusqlite benchmarks, .vox-cache L1 AST caches, and MENS .safetensors/.jsonl training artifacts).

1. Is Turso Indexing Better If We Support It?

1.1 Composite & Covering B-Tree Indexes — Immediate High-Leverage Win

turso = 0.6.1 (turso_core 0.6.1) implements full B-tree composite and covering index scans with range-scan pushdown. Cross-referencing crates/vox-db/src/schema/domains/*.rs against the query hot-paths in crates/vox-db/src/store/**/*.rs revealed 10 concrete index optimizations across our 118 tables:

#	Domain File	Table	Query Hot-Path / Issue	Recommended Turso Index
1	agents.rs	llm_interactions	ops_scientia.rs:420 filters WHERE task_category = ?1 AND trace_id IS NOT NULL ORDER BY created_at DESC LIMIT 1 (currently full table scan + sort)	CREATE INDEX IF NOT EXISTS idx_llm_interactions_cat_created ON llm_interactions(task_category, created_at DESC, trace_id);
2	agents.rs	llm_interactions	trials.rs:630 (partition_llm_spend) sums cost_usd partitioned by trial_run_label IS NOT NULL vs IS NULL across multi-KB prompt/response rows	Upgrade idx_llm_interactions_trial to covering index ON llm_interactions(trial_run_label, cost_usd) (100% index-only scan)
3	agents.rs	llm_attempts	Lookups by trace_id and attempt_number currently have zero secondary indexes	CREATE INDEX IF NOT EXISTS idx_llm_attempts_trace ON llm_attempts(trace_id, attempt_number);
4	publish_cloud.rs	scientia_external_intelligence	Queue polling by ingest_status and ingested_at_ms currently has zero secondary indexes	CREATE INDEX IF NOT EXISTS idx_scientia_ext_intel_status ON scientia_external_intelligence(ingest_status, ingested_at_ms DESC);
5	mens_intelligence.rs	corpus_pairs	Filtering by (label, origin) currently has zero secondary indexes	CREATE INDEX IF NOT EXISTS idx_corpus_pairs_label_origin ON corpus_pairs(label, origin);
6	scientia.rs	scientia_harness_decisions, scientia_harness_fix_proposals	Foreign keys REFERENCES scientia_harness_issues(id) ON DELETE CASCADE lack indexes on issue_id, forcing full table scans on parent delete	Add idx_scientia_harness_decisions_issue(issue_id) and idx_scientia_harness_fix_proposals_issue(issue_id)
7	agents.rs, knowledge.rs, foundation.rs	memories, behavior_events, learned_patterns, knowledge_edges, search_document_chunks, user_preferences, account_config	8 single-column indexes (idx_memories_agent, idx_behavior_user, idx_learned_patterns_user, idx_knowledge_edges_src, idx_knowledge_edges_dst, idx_search_chunks_doc, idx_user_preferences_user, idx_account_config_account) are strict left-prefixes of existing composite PKs or composite indexes	Drop the 8 redundant prefix indexes to eliminate unnecessary B-tree write amplification on every INSERT/UPDATE

1.2 Partial Indexes (CREATE INDEX ... WHERE ...) — Nuanced Tradeoff in Turso 0.6.1

• Parser vs. Bytecode Support: While turso 0.6.0-pre.8 rejected partial index WHERE clauses (Parse error: Partial indices are not supported yet), turso 0.6.1 parses and executes simple partial indexes (vox-db currently ships 4 partial indexes in conversations.rs:93, scientia.rs:431, and vox_mesh.rs:58,154).
• The Mutable-Nullable IdxDelete Hazard: As documented in crates/vox-db/src/schema/domains/scientia.rs:361-364, Turso 0.6.1 has an IdxDelete bytecode bug (no matching index entry) when a row’s indexed column transitions from NULL to non-NULL on UPDATE.
• Policy:
  • Use CREATE UNIQUE INDEX ... WHERE ... only on immutable/insert-time columns requiring partial uniqueness (conversations, scientia_harness_issues).
  • Use composite covering B-tree indexes (e.g. (trial_run_label, cost_usd)) instead of partial indexes on nullable lifecycle or telemetry columns: they avoid the IdxDelete hazard and simultaneously accelerate both IS NOT NULL and IS NULL aggregations via index-only scans.

1.3 Full-Text Search: Turso USING fts vs. vox-search tantivy

• Finding: crates/vox-db/src/schema_extensions.rs attempts PRAGMA compile_options + CREATE VIRTUAL TABLE ... USING fts5(...) + CREATE TRIGGER. As proven by crates/vox-db/tests/turso_fts_probe.rs, Turso does not implement C-SQLite’s fts5 virtual table module (schema_extensions.rs is dead code on Turso).
• Turso’s Native FTS (CREATE INDEX ... USING fts): Turso’s native FTS is itself a wrapper around tantivy inside turso_core (fts = ["dep:tantivy"]), gated behind --experimental-index-method.
• Tradeoff Verdict: Keep standalone tantivy 0.22 in vox-search::library::lexical as a derived index rebuilt from VoxDb rows. Enabling turso’s experimental fts feature would pull a duplicate tantivy 0.26 into the dependency graph, cannot index joined columns across search_documents.title + search_document_chunks.body_text, and lacks the custom BM25 field boosts (TITLE_BOOST = 0.25, HEADING_BOOST = 0.25) that lifted Vox’s KB retrieval nDCG@10 from 0.358 to 0.549.

1.4 Vector Indexing: Turso embeddings BLOB vs. External Qdrant

• Finding: At Vox’s corpus scale (< 25,000 chunks × 768 dims), brute-force f32 cosine similarity over Turso’s embeddings.vector BLOB (crates/vox-db/src/store/ops_memory/embedding.rs:70-138) executes in < 5 ms in-process with zero external network hops.
• Optimization: scientia_embedding_cache (crates/vox-db/src/schema/domains/scientia.rs:331-336) currently stores vectors as JSON TEXT (vector_json). Converting vector_json to little-endian f32 BLOB cuts storage 3.1× (9.5 KB -> 3.0 KB per 768-d vector) and eliminates JSON float-parsing overhead.

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2. Codebase-Wide Persistence Audit (“All TursoDB Unless Positive Tradeoff”)

#	Storage Surface	Location	Decision	Rationale / Action
1	Main Codex Store (store.db)	crates/vox-db/ (turso 0.6.1)	KEEP (Canonical TursoDB)	Primary workspace database (118 active tables).
2	Clavis Secret Vault (clavis_vault.db)	crates/vox-secrets/src/backend/vox_vault.rs (turso 0.6.1)	KEEP (TursoDB)	Uses TursoDB; separate ~/.vox/clavis_vault.db file isolates encrypted DEKs from project repos.
3	Populi Legacy JSON Stores (a2a-store.json, exec-lease-store.json, dispatch-store.json)	crates/vox-populi/src/transport/store/mod.rs:171-328	MIGRATE TO TURSO	No positive tradeoff. VoxDbMeshStore (vox_mesh.rs) already exists in vox-db; retire the JSON file fallback.
4	Mesh Replay State (mesh-replay-state.json)	crates/vox-populi/src/transport/mesh_replay.rs:25-136	MIGRATE TO TURSO	Whole-file JSON rewrite on every JWT jti check. Move to mesh_replay_nonces table in vox_mesh.rs.
5	Populi Local Node Registry (local-registry.json)	crates/vox-populi/src/node_registry.rs:23-103	MIGRATE TO TURSO	Whole-file JSON rewrite on heartbeats. Consolidate into node_identities / mesh_heartbeats in vox-db.
6	Telemetry Upload Queue Spool (pending/*.json)	crates/vox-cli/src/telemetry_spool.rs:1-170	MIGRATE TO TURSO	Directory of <uuid>.json files causes inode/stat churn. Replace with telemetry_upload_spool table in vox-db.
7	External Qdrant Vector Client (qdrant-vector)	crates/vox-search/src/vector_qdrant.rs:1-130	MIGRATE TO TURSO	External non-Turso server is unnecessary below 200k chunks; route CodeKnnIndex through VoxDb::search_similar_embeddings.
8	Model Catalog Cache (model-catalog.v1.json)	crates/vox-orchestrator/src/models/registry/catalog_seed.rs:163	MIGRATE TO TURSO	Store cached catalog payload inside VoxDb (model_pricing_catalog / user_preferences) to eliminate file/DB split-brain.
9	Unused bincode Dependencies	crates/vox-db/Cargo.toml:20, crates/vox-package/Cargo.toml:19	REMOVE DEAD DEPS	Zero call sites in vox-db or vox-package.
10	Tantivy Lexical Index (tantivy 0.22)	crates/vox-search/src/library/lexical.rs	KEEP (Positive Tradeoff)	100% derived cache rebuilt from Turso VoxDb rows; custom multi-table BM25 boosts (+53% nDCG@10).
11	Markdown Memory (MEMORY.md)	crates/vox-orchestrator/src/memory/manager.rs	KEEP (Positive Tradeoff)	Human-editable, git-diffable agent memory dual-written into Turso VoxDb (memories + knowledge_nodes).
12	vox-sql sqlx (postgres/mysql)	crates/vox-sql/Cargo.toml	KEEP (Positive Tradeoff)	Optional runtime adapter for user-authored Vox programs targeting external cloud DBs; isolated by run_sqlx_isolation_guard.
13	rusqlite 0.32 in vox-db	crates/vox-db/Cargo.toml:70 ([dev-dependencies])	KEEP (Positive Tradeoff)	Dev-only benchmark reference for comparing Turso vs. C-SQLite; never linked into production binaries.
14	L1 AST & Build Caches (.vox-cache/)	crates/vox-drift-check/src/cache.rs, crates/vox-package/src/artifact_cache.rs	KEEP (Positive Tradeoff)	Synchronous pre-commit L1 lint and compiler output directories that cannot depend on async vox-db per layers.toml.
15	MENS Corpora & Weights (.jsonl, .safetensors)	crates/vox-corpus/, crates/vox-quantize/	KEEP (Positive Tradeoff)	Native tensor weight and streaming dataset formats required by Candle, QLoRA, and HuggingFace Hub.