Data Integrity

Software Engineering 22 Sep 2026 6 min read

Optimistic Concurrency Control Rejects Stale Writes

Optimistic Concurrency Control Rejects Stale Writes Two clients can read the same record, make different edits, and save seconds apart. If each update blindly replaces the stored value, the later write can erase the earlier one even though both requests succeeded. Optimistic concurrency control prevents that silent overwrite by attaching a condition to the write. The client records a version when it reads the data. Its update succeeds only if that version is still current. A changed version turns the write into a conflict instead of an unnoticed loss.

Software Engineering Concurrency

Software Engineering 13 Sep 2026 10 min read

Version Columns Turn Lost Updates Into Conflicts

Two transactions can read the same row, compute different changes, and then write in sequence. If each update replaces values derived from its earlier read, the later write can erase part of the earlier one without either transaction observing a database error. A version column changes that interaction. The row carries a generation value alongside its domain fields, and an update is accepted only when the generation still matches the value observed by the writer. A stale writer no longer looks identical to a current writer at the storage boundary.

Software Engineering Databases

Cybersecurity 08 Sep 2026 10 min read

Use Authenticated Encryption for Data You Must Trust

Encrypting sensitive data can hide its contents while still leaving an important question unanswered: has the encrypted data been changed? If an application decrypts modified ciphertext without a reliable integrity check, it may consume attacker-influenced plaintext even though the attacker never learned the encryption key. That distinction matters anywhere decrypted data affects a security decision, a payment amount, a permission, a destination, or another meaningful application state. Confidentiality answers who can read the data. Integrity answers whether the protected data is the same data that an authorized key holder produced.

Cybersecurity Encryption