mirror of
https://github.com/ModernRelay/omnigraph.git
synced 2026-07-12 03:12:11 +02:00
66 lines
4.6 KiB
Markdown
66 lines
4.6 KiB
Markdown
# Query Language (`.gq`)
|
||
|
||
## Query declarations
|
||
|
||
```
|
||
query <name>($p1: T1, $p2: T2?, …)
|
||
@description("…") @instruction("…") {
|
||
…
|
||
}
|
||
```
|
||
|
||
Two body shapes:
|
||
|
||
- **Read**: `match { … } return { … } [order { … }] [limit N]` — covered on this page.
|
||
- **Mutation**: one or more of `insert | update | delete` statements — see [mutations](../mutations/index.md).
|
||
|
||
Multi-modal search functions (`nearest`, `bm25`, `rrf`, …) used inside `match`,
|
||
`return`, and `order` are documented on the [search](../search/index.md) page.
|
||
|
||
Param types reuse all schema scalars; trailing `?` makes a param optional. The compiler reserves `$__nanograph_now` for `now()`.
|
||
|
||
## MATCH clauses
|
||
|
||
- **Binding**: `$x: NodeType { prop: <literal | $param | now()>, … }`
|
||
- **Traversal**: `$src EDGE_NAME { min, max? } $dst` — variable-length paths via hop bounds; default 1..1 if bounds omitted.
|
||
- **Undirected traversal**: `$src <EDGE_NAME> $dst` — matches the edge in *either* direction with set semantics (a pair connected both ways, or a self-loop, appears once). Only valid on same-endpoint-type edges (e.g. `Related: Issue -> Issue`); an asymmetric edge is rejected at typecheck (`T22`) since it is well-typed in at most one orientation — use the directional form there. Composes with hop bounds (`$a <knows>{1,3} $b`) and `not { }` ("no edge in either direction").
|
||
- **Filter**: `<expr> <op> <expr>` with operators `>=`, `<=`, `!=`, `>`, `<`, `=`, and string `contains`.
|
||
- **Negation**: `not { clause+ }` — desugars to anti-join over the inner pipeline.
|
||
|
||
## RETURN clause
|
||
|
||
`return { <expr> [as <alias>], … }` with expressions:
|
||
|
||
- Variable / property access: `$x`, `$x.prop`
|
||
- Literals: string, int, float, bool, list
|
||
- `now()`
|
||
- Aggregates: `count`, `sum`, `avg`, `min`, `max`
|
||
- [Search functions](../search/index.md) (so you can return a score column)
|
||
- `AliasRef` — re-use a previous projection alias
|
||
|
||
## ORDER & LIMIT
|
||
|
||
- `order { <expr> [asc|desc], … }` — supports plain expressions and `nearest(...)`.
|
||
- `limit <integer>` — required when there is a `nearest(...)` ordering.
|
||
- **Total, deterministic order.** Rows with equal user-sort keys are broken by the bound entities' key columns (`<var>.id`, ascending) appended as a final tie-break, so the result is a *total* order — reproducible across runs, and `order … limit N` returns a deterministic top-N even when ties straddle the cutoff. (Aggregate results have no entity-key columns; their group rows are already distinct on the projected group keys.)
|
||
- **NULL placement** is *nulls-first ascending, nulls-last descending* (i.e. `nulls_first = !descending`): a NULL sorts as if smaller than any value.
|
||
|
||
Write statements (`insert` / `update` / `delete`) are documented on the
|
||
[mutations](../mutations/index.md) page.
|
||
|
||
## Traversal execution
|
||
|
||
Variable-length traversals (`Expand`) are executed one of two ways, chosen per-expand by a cost model over cheap manifest counts (frontier size, edge count, source-vertex count, hops) plus index coverage: selective traversals (small frontier relative to the source set) resolve neighbors from the persisted `src`/`dst` BTREE (one indexed scan per hop); dense / deep / large-frontier traversals — or those whose BTREE coverage is degraded so a full scan would be paid per hop — use an in-memory CSR adjacency index. Both produce identical results. An undirected traversal reads both adjacency directions — the CSR arm walks the outgoing and incoming index (both are always built), the indexed arm probes both the `src` and `dst` BTREE per hop — under the same per-source dedup, so its cost is roughly twice the directional equivalent. The `OMNIGRAPH_EXPAND_INDEXED_MAX_FRONTIER` / `OMNIGRAPH_EXPAND_INDEXED_MAX_HOPS` ceilings bound the *initial dispatch* frontier/hops (beyond them CSR is always used); the cost model estimates total indexed work as ~`hops × frontier × fanout` and prices dense fan-out toward CSR — they are not a hard per-hop bound. `OMNIGRAPH_TRAVERSAL_MODE=indexed|csr` forces a mode (see [constants](../reference/constants.md)).
|
||
|
||
## Linting & validation
|
||
|
||
Codes seen so far:
|
||
|
||
- **Q000** (Error): parse error
|
||
- **L201** (Warning): nullable property never set by any UPDATE — "{type}.{prop} exists in schema but no update query sets it"
|
||
- (Warning): mutation declares no params — hardcoded mutations are easy to miss
|
||
- Plus all type errors from type checking (undefined types, mismatched operators, undefined edges, etc.)
|
||
|
||
Lint output reports an overall status, per-query results (name, kind, status, any error and warnings), and structured findings (severity, code, message, and the type/property/query they apply to).
|
||
|
||
CLI exits non-zero only on `status = Error`.
|