https://vacua.dev/series/recovery-engineering/Recent content in Recovery Engineering on Brian FaustHugoen-USMon, 01 Jan 0001 00:00:00 +0000https://vacua.dev/thoughts/a-backup-is-only-an-input-to-recovery/Sat, 01 Aug 2026 00:00:00 +0000https://vacua.dev/thoughts/a-backup-is-only-an-input-to-recovery/<p>The backup job is green. The archive exists, its checksum matches, and <code>pg_restore</code> exits successfully. A shipment lookup still returns nothing.</p> <p>That is not a hypothetical combination. The <a href="https://vacua.dev/reproductions/ops-03/">OPS-03 fixture</a> contains a schema-only archive with a stable SHA-256 identity. PostgreSQL restores it without error. The tables and constraints exist. The application probe then asks for <code>shipment-100</code>, receives no row, and rejects the recovery.</p> <p>The checksum answered which bytes we selected. The restore command answered whether PostgreSQL could apply them. Neither answered whether the recovered database could do useful work.</p>