omnigraph/docs/user/schema/index.md
Andrew Altshuler d46e50dd6d
docs(user): restructure user docs into topic sections (Phase 1) (#223)
Move the 23 flat docs/user/*.md files into topic subdirectories so the
user guide is organized by area (schema, queries, search, branching, cli,
operations, clusters, concepts, reference) instead of a flat list. This is
a pure structural move — whole files relocated, every cross-doc link
recomputed, no prose rewrites or content splits (those follow in Phase 2).

- 19 `git mv`s (install.md, deployment.md stay top-level); history preserved
  (renames detected at 92–100% similarity).
- All intra-doc links, AGENTS.md's topic table (52 pointers), and the
  docs/dev + docs/releases back-links recomputed via relpath from each
  file's new location.
- docs/user/index.md rewritten as a sectioned nav hub.
- Fixed 5 doc-path references in Rust (comments + two user-facing server
  settings error strings) to point at the new locations.

Verified: zero broken .md links across tracked docs; check-agents-md.sh
green (with the untracked scratch docs set aside); touched crates build.

Note: the public site (omnigraph-web) imports docs/ via a flat-only script;
its import-docs.mjs needs a subdir-aware update before the next re-sync.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
2026-06-14 13:52:14 +03:00

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4.6 KiB
Markdown

# Schema Language (`.pg`)
Pest grammar at `crates/omnigraph-compiler/src/schema/schema.pest`. AST at `schema/ast.rs`. Catalog at `catalog/mod.rs`.
## Top-level declarations
- `interface <Name> { property* }` — reusable property contracts.
- `node <Name> [implements <Iface>, ...] { property* | constraint* }`
- `edge <Name>: <FromType> -> <ToType> [@card(min..max)] { property* | constraint* }`
- Comments: line `//` and block `/* … */`.
## Property declarations
`<ident>: <TypeRef> [annotation*]`
## Built-in scalar types
| Scalar | Arrow type |
|---|---|
| `String` | Utf8 |
| `Blob` | LargeBinary |
| `Bool` | Boolean |
| `I32` / `I64` | Int32 / Int64 |
| `U32` / `U64` | UInt32 / UInt64 |
| `F32` / `F64` | Float32 / Float64 |
| `Date` | Date32 |
| `DateTime` | Date64 |
| `Vector(<dim>)` | FixedSizeList(Float32, dim), `1 ≤ dim ≤ i32::MAX` |
| `[<scalar>]` | List(scalar) |
| `enum(v1, v2, …)` | Utf8 with sorted/dedup'd set of allowed string values |
| `<scalar>?` | Same as scalar but `nullable: true` |
## Constraints (body level)
| Constraint | On | Effect |
|---|---|---|
| `@key(p, …)` | node | Primary key; implies index on key columns; `key_property()` returns the first key |
| `@unique(p, …)` | node, edge | Uniqueness across listed columns |
| `@index(p, …)` | node, edge | Build a scalar (BTREE) index on the columns |
| `@range(p, min..max)` | node | Numeric range validation (open ranges allowed) |
| `@check(p, "regex")` | node | Regex pattern validation |
| `@card(min..max?)` | edge | Edge multiplicity — default `0..*`; `0..1`, `1..1`, `1..*`, etc. |
Edge bodies only allow `@unique` and `@index`.
## Annotations
- `@<ident>` or `@<ident>(<literal>)` on any declaration or property.
- Known annotations:
- `@embed` on a Vector property — names the *source* property whose text gets embedded into this vector at ingest (`embed_sources` map in NodeType).
- `@description("…")`, `@instruction("…")` on query declarations (carried through to clients).
- Custom annotations are accepted by the parser and surfaced in catalog metadata; unrecognized annotations don't fail compilation.
## Catalog construction
- Pass 0: collect interfaces.
- Pass 1: collect nodes, expand `implements`, build constraint and `@embed` mappings, build the Arrow schema for each node table (`id: Utf8` plus all properties; blob columns get `LargeBinary`).
- Pass 2: collect edges, validate that `from_type` / `to_type` exist, normalize edge names case-insensitively for lookup, validate constraints for edges. Edge Arrow schema: `id: Utf8, src: Utf8, dst: Utf8` plus edge properties.
## Schema IR & stable type IDs
- `SCHEMA_IR_VERSION = 1` (`catalog/schema_ir.rs`).
- Each interface/node/edge currently gets a `stable_type_id` from a kind+name hash.
- Rename-preserving accepted IDs are an architectural invariant, but the current hash-on-name implementation is a known gap until migration carries IDs across `@rename_from`.
- Serialized as JSON for diff/migration plans.
## Schema migration planning
`plan_schema_migration(accepted, desired) -> SchemaMigrationPlan { supported, steps[] }` with step types:
- `AddType { type_kind, name }`
- `RenameType { type_kind, from, to }`
- `AddProperty { type_kind, type_name, property_name, property_type }`
- `RenameProperty { type_kind, type_name, from, to }`
- `AddConstraint { type_kind, type_name, constraint }`
- `UpdateTypeMetadata { … annotations }`
- `UpdatePropertyMetadata { … annotations }`
- `UnsupportedChange { entity, reason }` (forces `supported=false`)
`apply_schema()` returns `SchemaApplyResult { supported, applied, manifest_version, steps }` and is gated by an internal `__schema_apply_lock__` system branch so concurrent schema applies serialize.
## Destructive drops — `--allow-data-loss`
`DropProperty` and `DropType` steps default to `Soft` mode: the catalog tombstones the entry but the prior column / dataset remains time-travel-reachable via `snapshot_at_version(prev)` until `omnigraph cleanup` runs. Soft drops are reversible.
Pass `--allow-data-loss` (CLI) or `allow_data_loss: true` (HTTP `POST /schema/apply` body, SDK `SchemaApplyOptions`) to promote every drop in the plan to `Hard` mode. Hard drops run `cleanup_old_versions` on the affected dataset immediately after the manifest publish, making the prior column / dataset unreachable. **Irreversible.**
The flag is honored uniformly across transports — `omnigraph schema apply --allow-data-loss`, `POST /schema/apply { schema_source, allow_data_loss: true }`, and `apply_schema_with_options(.., SchemaApplyOptions { allow_data_loss: true })` produce identical plans and identical effects.