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70ed848b9d
Document the optional @embed model kwarg, the query-time same-space rejection, model-string strictness, and the loud schema-apply refusal on model change. Mark RFC-012 phases 1-4 implemented.
77 lines
4.3 KiB
Markdown
77 lines
4.3 KiB
Markdown
# Schema Language (`.pg`)
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## Top-level declarations
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- `interface <Name> { property* }` — reusable property contracts.
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- `node <Name> [implements <Iface>, ...] { property* | constraint* }`
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- `edge <Name>: <FromType> -> <ToType> [@card(min..max)] { property* | constraint* }`
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- Comments: line `//` and block `/* … */`.
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## Property declarations
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`<ident>: <TypeRef> [annotation*]`
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## Built-in scalar types
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| Scalar | Arrow type |
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|---|---|
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| `String` | Utf8 |
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| `Blob` | LargeBinary |
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| `Bool` | Boolean |
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| `I32` / `I64` | Int32 / Int64 |
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| `U32` / `U64` | UInt32 / UInt64 |
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| `F32` / `F64` | Float32 / Float64 |
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| `Date` | Date32 |
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| `DateTime` | Date64 |
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| `Vector(<dim>)` | FixedSizeList(Float32, dim), `1 ≤ dim ≤ i32::MAX` |
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| `[<scalar>]` | List(scalar) |
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| `enum(v1, v2, …)` | Utf8 with sorted/dedup'd set of allowed string values |
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| `<scalar>?` | Same as scalar but `nullable: true` |
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## Constraints (body level)
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| Constraint | On | Effect |
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|---|---|---|
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| `@key(p, …)` | node | Primary key; implies index on key columns; `key_property()` returns the first key |
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| `@unique(p, …)` | node, edge | Uniqueness across listed columns |
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| `@index(p, …)` | node, edge | Build a scalar (BTREE) index on the columns |
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| `@range(p, min..max)` | node | Numeric range validation (open ranges allowed) |
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| `@check(p, "regex")` | node | Regex pattern validation |
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| `@card(min..max?)` | edge | Edge multiplicity — default `0..*`; `0..1`, `1..1`, `1..*`, etc. |
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Edge bodies only allow `@unique` and `@index`.
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## Annotations
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- `@<ident>` or `@<ident>(<literal>)` on any declaration or property.
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- Known annotations:
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- `@embed("source_property")` on a Vector property — records which String property is the embedding source for query-time `nearest($v, "string")` auto-embedding. It is a catalog annotation; it does **not** populate the vector at ingest (supply vectors in load data, or pre-fill via the offline `omnigraph embed` pipeline). An optional `model="…"` kwarg (`@embed("source_property", model="openai/text-embedding-3-large")`) records the embedding model so a `nearest()` query whose embedder uses a different model is rejected loudly; `model` is the only supported kwarg. See [search/embeddings.md](../search/embeddings.md).
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- `@description("…")`, `@instruction("…")` on query declarations (carried through to clients).
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- Custom annotations are accepted by the parser and surfaced in catalog metadata; unrecognized annotations don't fail compilation.
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## Table layout
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- 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.
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- 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.
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## Schema migration planning
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A migration plan compares the accepted schema against the desired one and reports whether the change is supported plus the ordered steps it requires:
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- Add a type
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- Rename a type
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- Add a property
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- Rename a property
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- Add a constraint
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- Update type or property metadata (annotations)
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- Unsupported change (reports the entity and reason; forces the plan to unsupported)
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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.
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## Destructive drops — `--allow-data-loss`
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`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.
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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.**
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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.
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