django-migration-linter/docs/incompatibilities.md

Backward incompatible migrations

The linter analyses your migrations and checks the SQL for:

• Added NOT NULL columns, which don't have a DEFAULT value
• Dropping columns
• Dropping tables
• Renaming columns
• Renaming tables
• Altering columns (which can be backward compatible and potentially ignored)
• Adding a unique constraint

Those are the most important and frequent backward incompatible migrations. We are happy to add more if you can specify them to us.

Warnings

On data migrations, the linter will show a warning when:

• you are missing a reverse migration
• the RunPython arguments do not respect the naming convention apps, schema_editor
• the model variable name is different from the model class name in the get_model call

Codes

You can ignore checks through the --exclude-migration-tests option by specifying any of the codes:

Code	Description	Default type
NOT_NULL	Not NULL constraint on columns	Error
DROP_COLUMN	Dropping columns	Error
DROP_TABLE	Dropping tables	Error
RENAME_COLUMN	Renaming columns	Error
RENAME_TABLE	Renaming tables	Error
ALTER_COLUMN	Altering columns (could be backward compatible)	Error
ADD_UNIQUE	Add unique constraints	Error
RUNPYTHON_REVERSIBLE	RunPython data migration is not reversible (missing reverse code)	Warning
RUNPYTHON_ARGS_NAMING_CONVENTION	By convention, RunPython names two arguments: apps, schema_editor	Warning
RUNPYTHON_MODEL_IMPORT	Missing apps.get_model() calls for model	Error
RUNPYTHON_MODEL_VARIABLE_NAME	The model variable name is different from the model class itself	Warning
RUNSQL_REVERSIBLE	RunSQL data migration is not reversible (missing reverse SQL)	Warning
CREATE_INDEX	(Postgresql specific) Creating an index without the concurrent keyword will lock the table and may generate downtime	Warning
DROP_INDEX	(Postgresql specific) Dropping an index without the concurrent keyword will lock the table and may generate downtime	Warning
REINDEX	(Postgresql specific) Reindexing will lock the table and may generate downtime	Warning