mmk down

Roll back migrations — the last batch, a specific batch, the last N, or a single file.

mmk down [file] [options]

Usage

mmk down                 # roll back the last batch
mmk down <file>          # roll back a single migration by filename
mmk down --batch <n>     # roll back every migration in batch n
mmk down --steps <n>     # roll back the last N migrations, newest first
mmk down --force         # roll back even if a file drifted (asks for confirmation)

How it works

With no argument, mmk down reverts the most recent batch — every migration that shares the highest batch number — by calling each file's down() in reverse order.

↩ Reverted 20260605120500-backfill-status.js     [54ms]
↩ Reverted 20260605120000-add-users-index.js     [21ms]

History is never deleted: each reverted record has its status set to reverted and a revertedAt timestamp, preserving the full audit trail.

Options

Option	Description
[file]	Revert only this migration file.
--batch <n>	Revert every migration in batch number n.
--steps <n>	Revert the last N applied migrations, newest first, ignoring batch grouping.
--force	Roll back even if a file's checksum drifted from what was applied (prompts for confirmation).
--yes	Confirm --force non-interactively (required with --json).
--no-lock	Skip the concurrency lock. Dev only.
--json	Emit the run results as a JSON array on stdout.

Plus the global flags.

Mutually exclusive

--steps cannot be combined with a [file] or with --batch. Doing so exits with a validation error before connecting to the database.

Checksum verification

Before reverting, mmk down recomputes each target file's SHA-256 and compares it to the checksum recorded when the migration was applied. If a file drifted (was edited after it ran), the rollback is refused up front — the whole batch aborts before anything is reverted — with a ChecksumMismatchError:

✖ Checksum mismatch — refusing to roll back drifted file(s): 20260605120000-add-users-index.js

This is stricter than mmk up, which only blocks under strict and otherwise skips: running an edited down() against production is the riskiest place to execute unverified code, so down blocks regardless of the strict setting.

To roll back the drifted file anyway — running its current down() — pass --force. It prompts for confirmation (--yes to skip, required in --json mode). mmk redo forces this internally, since redoing an edited migration is the usual reason to run it.

--steps — Laravel-style rollback

--steps <n> reverts the last n applied migrations as individual files, newest first (ordered by appliedAt), regardless of which batch they belong to:

mmk down --steps 2   # undo the two most recently applied migrations

This differs from the default (revert the whole last batch) and from --batch <n> (revert one specific batch).

Forward-only / imported migrations

Migrations adopted via mmk import are tagged origin: 'migrate-mongo' and are not reversible. mmk down preflights this and throws IrreversibleMigrationError before touching anything, so the collection is never left half-reverted.

Exit codes

Code	Meaning
0	The targeted migrations were reverted.
1	A down() threw, a target wasn't applied (NotAppliedError), a file drifted without --force (ChecksumMismatchError), or validation failed.