Provides a thin abstraction over memory-mapped files (Mmap) and owned byte vectors (Vec<u8>), enabling production use of mmap-backed data and test use of owned byte arrays without code duplication. The type supports Arc sharing and is used as the backing store for all on-disk graph artifacts. It is a self-contained, highly reusable pattern for any Rust project that needs to switch between mmap and owned memory.

Implements a ResourceGovernor with typed budgets for memory, disk, rows, work units, and elapsed time, along with ResourceLease and DiskLease RAII wrappers. It enforces quotas via try_reserve and check_postgres_interrupts, and supports adaptive batch flushing. Though coupled to PostgreSQL error handling, the core pattern of resource accounting with phases and leases is architecturally clean and could be extracted as a standalone Rust crate for resource-constrained execution.

Manages a cumulative, CRC32-checksummed mapping from edge type IDs to logical labels (OIDs). Supports append-only growth with atomic publication via manifest, and is read via mmap. The design ensures that all historical mappings remain valid and that dictionary files can be validated on load. This pattern is reusable for any system needing a durable, append-only, checksummed dictionary for enumerated types.