omnigraph/docs/user/schema/index.md
Andrew Altshuler 77dffdae92
docs(user): de-dev polish — strip internal scaffolding from user docs (Phase 3a) (#226)
Remove developer-only scaffolding that leaked into the public user/operator
docs, while preserving every user-facing behavior, command, flag, endpoint,
constant, and env var. No behavior changes.

Removed across 18 files:
- internal ticket / sequencing refs (MR-NNN, RFC-NNN, "Phase N");
- source-code paths (crates/**/*.rs, *.pest) and internal struct/function
  dumps (e.g. the QueryIR / GraphCommit / SchemaMigrationPlan Rust types,
  internal fn names like fork_branch_from_state, optimize_all_tables);
- Lance-internal blocker prose (upstream issue numbers, blob-decode cause,
  sidecar Phase-B/C mechanics) — keeping the user-visible behavior (e.g.
  "optimize skips Blob-column tables; reads/writes unaffected");
- pre-v0.4.0 Run-state-machine archaeology.

Internal IR/lowering/recovery-internals sections were either trimmed to a
brief user-facing note (e.g. "Traversal execution", "interrupted writes
recover automatically; recovery commits are recorded under actor
omnigraph:recovery") or removed.

Kept: all language syntax, lint codes, Cedar actions/scopes, endpoints,
error taxonomy, every constant and env var (verified none dropped from the
constants cheat-sheet), and the operator-facing explanations of on-disk
artifacts. Residual "legacy" mentions are all user-facing (the deprecated
omnigraph.yaml, the legacy token chain, old command names).

Verified: zero internal-scaffolding leaks (MR/RFC/Phase/.rs/.pest = 0) across
docs/user; zero broken links; check-agents-md.sh green.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
2026-06-14 14:39:25 +03:00

77 lines
3.8 KiB
Markdown

# Schema Language (`.pg`)
## 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.
- `@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.
## Table layout
- Each node type compiles to a table with an `id: Utf8` column plus all declared properties (blob columns are stored as `LargeBinary`); `implements` clauses expand the interface's properties into the node.
- Each edge type compiles to a table with `id: Utf8, src: Utf8, dst: Utf8` plus the edge's own properties. Edge endpoint types (`from`/`to`) must exist, and edge names are matched case-insensitively.
## Schema migration planning
A migration plan compares the accepted schema against the desired one and reports whether the change is supported plus the ordered steps it requires:
- Add a type
- Rename a type
- Add a property
- Rename a property
- Add a constraint
- Update type or property metadata (annotations)
- Unsupported change (reports the entity and reason; forces the plan to unsupported)
Applying a plan reports whether it was supported, the steps applied, and the resulting manifest version. Concurrent schema applies serialize so they can't interleave.
## 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.