ukmesh/docs/db-lifecycle.md

DB Lifecycle

Rules

• backend/src/db/schema/base.sql
  • only cheap, idempotent base schema work
• backend/src/db/migrations.ts
  • runs additive versioned migrations
• historical backfills must not run on backend startup

Use the right layer

Base schema

Use for:

• table creation
• index creation
• safe ALTER TABLE ... ADD COLUMN IF NOT EXISTS

Do not use for:

• whole-table UPDATE backfills
• historical recomputation
• data repair

Migrations

Use for:

• additive schema changes that need one-time application
• constraints or indexes that belong to a versioned rollout

Backfills / maintenance jobs

Use for:

• recomputing derived packet fields
• rebuilding link tables
• recalculating historical summaries

Run historical work deliberately during a low-traffic window. For example, after building the current backend image, reconstruct the bounded stats rollups without restarting the live API:

docker compose build backend
docker compose run --rm --no-deps backend node dist/tools/backfillStatsRollups.js --apply

backfillStatsRollups uses independent daily/24-hour slices and monotonic upserts, so a live ingest write cannot be replaced by an older candidate. It defaults to the same 31 calendar dates used by the longest-hop API and the eight-day observer-window retention boundary. It is idempotent; use --daily-days or --observer-days only when an operator intentionally wants a different bounded window.

Startup guarantee

Backend startup should be safe against a production-sized database. If a change can lock or scan large tables, it does not belong in startup schema init.

Compose deployment

docker compose up -d --build runs the one-shot db-migrate service after TimescaleDB becomes healthy and before the backend starts. It applies only unrecorded files from backend/src/db/migrations/; after a successful run it exits with no changes on later deploys.

Existing production services keep DATABASE_SKIP_SCHEMA_INIT=true, so they do not repeat base-schema DDL during ordinary startup. For a manual migration run, use docker compose run --rm db-migrate and inspect its output before starting new application containers.

Production network-label cutover

The historical teesside and northeast labels remain read-compatible until a deliberate cutover. Start with a non-mutating audit:

scripts/unify-networks.sh audit

Before applying, stop or upgrade every writer, create and verify a database/volume snapshot, and record its identifier. The apply command refuses to run if a legacy-labelled packet arrived in the last 15 minutes, if confirmation is absent, or if no backup reference is supplied:

CONFIRM_NETWORK_UNIFICATION=ukmesh \
BACKUP_REFERENCE='snapshot-2026-07-11T1600Z' \
scripts/unify-networks.sh apply

The workflow preserves sighting intervals, updates status history in 50,000-row commits, rewrites packet chunks individually, restores the prior compression-policy state after interruption, and records progress in network_unification_runs. Re-running with the same NETWORK_UNIFICATION_RUN_ID is safe. Run scripts/unify-networks.sh verify after any interrupted maintenance.

The relabel discards the distinction between historical production labels and is not logically reversible. Rollback means stopping all writers, restoring the snapshot named by BACKUP_REFERENCE, restoring the matching application version, and only then reopening ingest. Do not attempt a reverse UPDATE: the original label cannot be reconstructed reliably after unification.