What is Audit Trail?
An append-only log recording who changed what and when, written by triggers or application events. Audits answer incident questions no snapshot can: intent, actor, and exact sequence of changes.
Related terms
Retention & Purge Policy
A documented policy deleting or archiving rows after their useful life, enforced by scheduled jobs. Retention bounds table growth, honors privacy promises, and keeps backups and queries fast.
Soft Delete & Tombstones
Marking rows deleted with a timestamp flag instead of removing them, preserving history and undo. BYOB keeps a soft-delete grace window on projects before hard purge, so accidents stay recoverable.
Migration Tracking Table
The ledger recording which migrations already ran, so deploys apply each exactly once in order. Drizzle and Supabase both maintain one; never edit it by hand unless repairing a failed deploy.
B-Tree Index
The default balanced-tree structure making equality and range lookups fast without scanning every row. Add one where queries filter, join, or sort — then confirm with EXPLAIN before assuming victory.
Composite Index
One index spanning several columns for queries that always filter them together, ordered most-selective first. A three-column composite beats three single-column indexes on the same query shape.
Partial Index
An index covering only rows matching a predicate, such as live subscriptions where status is active. Smaller, faster, and cheaper to maintain than indexing rows queries never touch.