# tollgate-store-postgres
The PostgreSQL backend of [Tollgate](https://github.com/MorphIQ-Labs/tollgate):
transactional fenced lease allocation, idempotent usage ingest, snapshot and
credential storage, and bounded expiry reclaim, implementing the
[`tollgate-store`](https://crates.io/crates/tollgate-store) traits.
It reproduces `MemoryStore`'s settlement rules exactly. A mirrored test suite,
matched to the in-memory backend's scenario by scenario, is the proof, and
repository checks keep the two suites driving one contract.
- **Concurrency** is row-level: `SELECT … FOR UPDATE` on the account row for
acquisition, and on the lease row to serialise release, ingest, and reclaim.
- **Fencing tokens** come from a per-account counter, so allocation is
strictly monotonic per account across any number of servers sharing the
database.
- **Arithmetic** is checked in both directions: units are `BIGINT` with
checked conversion, a balance beyond `i64::MAX` is refused rather than
wrapped, and schema constraints keep every unit column non-negative.
- **Usage ingest** is set-wise; **expiry reclaim** runs in bounded,
set-wise `SKIP LOCKED` batches, oldest due first, in index order.
- **Migrations** are embedded and run on connect.
The conservation equation holds on this backend as on every other, and a
reconciliation query checks it on a live database.
## Features
- `test-support`: destructive fixture reset and query-plan inspection, for
tests. Not for production builds, and not covered by semantic versioning: it
may change in any release.
## Documentation
[`docs/USAGE_ACCOUNTING.md`](https://github.com/MorphIQ-Labs/tollgate/blob/main/docs/USAGE_ACCOUNTING.md)
covers batch rejection semantics, PostgreSQL numeric limits, and
database-guard migration and recovery;
[`docs/LEASE_OWNERSHIP.md`](https://github.com/MorphIQ-Labs/tollgate/blob/main/docs/LEASE_OWNERSHIP.md)
covers grant retirement. The contract is
[`INVARIANTS.md`](https://github.com/MorphIQ-Labs/tollgate/blob/main/INVARIANTS.md).
## License
MIT OR Apache-2.0, at your option. Tollgate is a product of MorphIQ Labs, a
trade name of Prophetizo LLC.