0-2-3-understand-tl-update-record

name	0.2.3-understand-tl_update_record
description	[0.2.3] A log_record capturing a before_image and after_image of a modified data page or row; used by both redo_recove

understand-tl_update_record

CALL NUMBER: deep_database_transaction.tl_update_record DEFINITION: A log_record capturing a before_image and after_image of a modified data page or row; used by both redo_recovery (for durability) and undo_recovery (for atomicity rollback).

Invoke this skill to understand tl_update_record 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

• tl_redo_log (d1): A log_record or series of tl_update_record entries capturing the after_image of modifications; replayed by recovery_manager to idempotently reconstruct committed changes after a crash.
• tl_undo_log (d1): A structured collection of tl_update_record entries chained by a transaction; traversed in reverse order during rollback to restore the before_image of each modified entity.
• tl_abort_record (d2): A log_record written when a transaction enters the aborted_state; signals that undo_log entries must be applied to reverse this transaction's effects.

CONSUMERS (what needs this)

tl_log_record

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Projected from the database transaction isolation and concurrency control KB (217 concepts / 124 relations) — consistency-typed by MAP; the facet list after the colon IS the cross-lib dependency web.

(leaf — this is an actual skill.)