Lint rules

Migrax lints every migration it generates, and migrax lint checks pending migrations (or --all, or named files). Each finding explains the risk and a safer alternative.

Severity: errors make lint exit with 1. Warnings do too with --strict. Info findings are advice.

To accept a finding on purpose, add a directive on the line before the statement:

-- migrax:lint-ignore MX007
ALTER TABLE customers DROP COLUMN legacy_code;

Code	Severity	Database	Finds	Safer alternative
MX001	warning	PostgreSQL	CREATE INDEX on an existing table without CONCURRENTLY blocks writes until it finishes	CREATE INDEX CONCURRENTLY in its own -- migrax:no-transaction migration (generate --safe does this)
MX002	warning	all	NOT NULL column without a default on an existing table fails when the table has rows	Add a DEFAULT, or add it nullable, backfill, then make it NOT NULL
MX003	warning	all	Column type change can rewrite or lock the table, and fails or truncates when the type gets narrower	Test on a production-size copy; for large tables add a new column, backfill, switch, drop
MX004	warning	PostgreSQL	SET NOT NULL scans the table under an exclusive lock	CHECK (col IS NOT NULL) NOT VALID, then VALIDATE CONSTRAINT later
MX005	warning	PostgreSQL	Adding a foreign key checks every row while blocking writes to both tables	Add it NOT VALID, validate in a later migration (generate --safe)
MX006	warning	PostgreSQL	Adding a unique constraint builds its index while blocking writes	CREATE UNIQUE INDEX CONCURRENTLY, then ADD CONSTRAINT ... UNIQUE USING INDEX (generate --safe)
MX007	warning	all	Dropping a table or column deletes data and breaks instances still using it	Deploy code that no longer uses it, then drop in a later release
MX008	warning	all	Renaming breaks instances still running the old code	Rename in steps (add, write both, switch reads, remove) or use a maintenance window
MX009	warning	all	UPDATE or DELETE without WHERE changes every row in one transaction	Add a WHERE, or update large tables in batches
MX010	warning	all	TRUNCATE deletes all rows and cannot be undone by a rollback script	Make sure it is intended and backed up
MX011	warning	PostgreSQL	A volatile default rewrites every row under an exclusive lock	Add the column without a default, set the default separately, backfill in batches
MX012	error	PostgreSQL	A statement that cannot run inside a transaction (CREATE INDEX CONCURRENTLY, VACUUM, ...)	Add -- migrax:no-transaction to the migration
MX013	warning	PostgreSQL	Adding a primary key builds an index while blocking writes	CREATE UNIQUE INDEX CONCURRENTLY, then ADD CONSTRAINT ... PRIMARY KEY USING INDEX
MX014	warning	PostgreSQL	Adding a check constraint scans the table under an exclusive lock	Add it NOT VALID, then VALIDATE CONSTRAINT later
MX015	info	SQL Server, Oracle	Index builds lock the table unless they run online	WITH (ONLINE = ON) (SQL Server Enterprise) or ONLINE (Oracle Enterprise)
MX000	error	all	The migration could not be parsed	Fix the SQL