| name | 0.3.5-understand-dur_recovery_manager |
| description | [0.3.5] The subsystem that enforces durability by reconstructing the committed database state from transaction_log aft |
understand-dur_recovery_manager
CALL NUMBER: deep_database_transaction.dur_recovery_manager
DEFINITION: The subsystem that enforces durability by reconstructing the committed database state from transaction_log after a crash; scans log forward to redo committed changes and backward to undo uncommitted ones.
Invoke this skill to understand dur_recovery_manager down to its primitives. The RELATIVE ROOT below is the least-fixed-point closure of everything it bundles from — the full import cone, grouped by the lib each prim comes from. Projected from a prover-typed KB (MAP/SWI-Prolog consistency gate): every reference below resolves.
THE RELATIVE ROOT (the import cone, by lib)
from deep_database_transaction
- dur_redo_log (d1): Log records describing the after-image of modified data; during recovery the manager reapplies these records to restore committed transaction effects.
- dur_undo_log (d1): Log records describing the before-image of modified data; used during rollback and recovery to reverse uncommitted changes, preserving durability by ensuring only committed effects survive.
- dur_write_ahead_logging (d1): A protocol mandating that log records describing modifications be flushed to durable_storage before the corresponding data pages are written to disk; foundational mechanism for both atomicity and durability.
- dur_log_flush (d2): The synchronous I/O operation that transfers log buffers from volatile memory to durable_storage; must complete before commit returns success to the client.
- dur_durable_storage (d3): The physical medium or storage subsystem that guarantees bitwise persistence of written data across power loss, hardware failure, and system crashes; the endpoint of all durability guarantees.
CONSUMERS (what needs this)
dur_crash_recovery, recovery_manager
Projected from the database transaction isolation and concurrency control KB (280 concepts / 214 relations) — consistency-typed by MAP; the facet list after the colon IS the cross-lib dependency web.
(leaf — this is an actual skill.)
