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80 lines
3.7 KiB
Markdown
80 lines
3.7 KiB
Markdown
# Schema Language (`.pg`)
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Pest grammar at `crates/omnigraph-compiler/src/schema/schema.pest`. AST at `schema/ast.rs`. Catalog at `catalog/mod.rs`.
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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` on a Vector property — names the *source* property whose text gets embedded into this vector at ingest (`embed_sources` map in NodeType).
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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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## Catalog construction
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- Pass 0: collect interfaces.
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- 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`).
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- 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.
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## Schema IR & stable type IDs
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- `SCHEMA_IR_VERSION = 1` (`catalog/schema_ir.rs`).
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- Each interface/node/edge currently gets a `stable_type_id` from a kind+name hash.
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- 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`.
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- Serialized as JSON for diff/migration plans.
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## Schema migration planning
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`plan_schema_migration(accepted, desired) -> SchemaMigrationPlan { supported, steps[] }` with step types:
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- `AddType { type_kind, name }`
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- `RenameType { type_kind, from, to }`
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- `AddProperty { type_kind, type_name, property_name, property_type }`
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- `RenameProperty { type_kind, type_name, from, to }`
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- `AddConstraint { type_kind, type_name, constraint }`
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- `UpdateTypeMetadata { … annotations }`
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- `UpdatePropertyMetadata { … annotations }`
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- `UnsupportedChange { entity, reason }` (forces `supported=false`)
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`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.
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