Squawk — a linter for Postgres migrations

Prevent Downtime

Lint your schema changes and prevent blocking reads / writes.

GitHub Integration

Use the Squawk GitHub App to lint your pull requests.

VSCode Support

Squawk's language server and VSCode extension provides linting in your editor.

Rules

Prevent schema mistakes

rule name	description
ban-char-field	Prevent mistaken use of character type in schema.
prefer-bigint-over-int	Prevent hitting the 32 bit max int limit.
prefer-bigint-over-smallint	Prevent hitting the 16 bit max int limit.
prefer-identity	Serial types have confusing behaviors. Use identity columns instead.
prefer-timestamptz	Ensure consistent timezone handling for timestamps, regardless of your database session timezone.
ban-concurrent-index-creation-in-transaction	Prevent forbidden use of transactions during concurrent index creation.
ban-create-domain-with-constraint	Domains with constraints have poor support for online migrations
ban-alter-domain-with-add-constraint	Domains with constraints have poor support for online migrations
ban-uncommitted-transaction	Ensure all transactions are committed
require-enum-value-ordering	Require BEFORE or AFTER when adding enum values
require-table-schema	Require explicit schema in table DDL to avoid ambiguity.
identifier-too-long	Prevent implicit truncation for identifiers that are too long.
require-concurrent-partition-detach	Prevent blocking reads/writes to table while partition is detached.

Make backwards compatible schema changes

rule name	description
adding-required-field	Prevent adding a new required field to an existing table.
ban-drop-database	Prevent breaking existing clients that depend on the database.
ban-drop-not-null	Prevent breaking existing clients that don't expect NULL values.
ban-drop-table	Prevent breaking existing clients that depend on the table.
changing-column-type	Prevent breaking existing clients that depend on column type. Prevent blocking reads/writes to table while table is rewritten.
renaming-column	Prevent breaking existing clients that depend on column.
renaming-table	Prevent breaking existing clients that depend on table.
ban-truncate-cascade	Truncate cascade will recursively truncate all related tables!
ban-drop-view	Prevent breaking clients that depend on views or materialized views.
ban-drop-function	Prevent breaking clients that call functions or procedures.
ban-drop-type	Prevent breaking clients that use dropped types.
ban-drop-default	Prevent inserts from failing or writing NULL after dropping a column default.
ban-drop-trigger	Prevent silent changes when a trigger is dropped (opt-in).
ban-drop-schema	Prevent breaking clients that use a dropped schema.
ban-drop-sequence	Prevent breaking clients that use a dropped sequence.
ban-drop-domain	Prevent breaking clients that use a dropped domain.
ban-drop-constraint	Prevent removing a constraint guarantee.
ban-drop-generated-expression	Prevent dropping a generated expression.
renaming-object	Prevent renaming objects used by clients.
ban-set-schema	Prevent moving objects used by clients to another schema.
ban-alter-identity	Prevent changing identity columns used by clients.
ban-drop-extension	Prevent dropping extensions used by clients.
ban-alter-generated-expression	Prevent breaking inserts with generated columns (opt-in).
ban-drop-index	Prevent dropping indexes used by clients (opt-in).
ban-set-default	Prevent silent changes to column defaults (opt-in).
ban-disable-trigger	Prevent changes to triggers, rules, and row level security (opt-in).
ban-replica-identity	Detect changes to replica identity and publications (opt-in).
ban-drop-policy	Prevent dropping policies and rules (opt-in).
ban-revoke	Prevent revoking client privileges (opt-in).
ban-replace-view-function	Prevent replacing views and routines (opt-in).
ban-create-policy	Review new policy access rules (opt-in).
ban-alter-policy-condition	Review policy condition changes (opt-in).
ban-alter-policy-roles	Review policy role changes (opt-in).
ban-alter-function-options	Review function option changes (opt-in).
ban-alter-view-options	Review view option changes (opt-in).
ban-alter-role-options	Review role option and configuration changes (opt-in).
ban-alter-database-options	Review database option and configuration changes (opt-in).
ban-alter-row-level-security	Review row level security changes (opt-in).
ban-new-write-restriction	Detect new write restrictions on existing tables (opt-in).
ban-add-enum-value	Detect new enum values (opt-in).
ban-add-composite-attribute	Detect new composite attributes (opt-in).
ban-add-column	Detect columns added to existing tables (opt-in).
ban-detach-inheritance	Detect partition detach and NO INHERIT (opt-in).
ban-alter-sequence-values	Detect changes to sequence values (opt-in).
ban-alter-system-options	Review server configuration changes (opt-in).
ban-alter-extension	Review extension updates and member removals (opt-in).

Apply schema changes safely

rule name	description
adding-field-with-default	Prevent blocking reads/writes to table while table is rewritten on PG < 11.
adding-foreign-key-constraint	Prevent blocking writes to tables while verifying foreign key constraint.
adding-not-nullable-field	Prevent blocking reads/writes to table while table is scanned on PG < 11.
adding-serial-primary-key-field	Prevent blocking reads/writes to table while index is built.
changing-column-type	Prevent breaking existing clients that depend on column type. Prevent blocking reads/writes to table while table is rewritten.
constraint-missing-not-valid	Prevent blocking writes to the table while the scan occurs.
disallowed-unique-constraint	Prevent blocking reads/writes to table while index is built.
prefer-robust-stmts	Ensure migrations are atomic or retriable.
prefer-text-field	Prevent blocking reads and writes to table while table metadata is updated.
require-concurrent-index-creation	Prevent blocking writes to table while index is created.
require-concurrent-index-deletion	Prevent blocking reads/writes to table while index is dropped.
transaction-nesting	Ensure migrations use transactions correctly.
ban-create-domain-with-constraint	Domains with constraints have poor support for online migrations
ban-alter-domain-with-add-constraint	Domains with constraints have poor support for online migrations
require-lock-timeout	Require a lock timeout
require-statement-timeout	Require a statement timeout
require-concurrent-partition-detach	Prevent blocking reads/writes to table while partition is detached.
require-concurrent-reindex	Prevent blocking reads/writes to table while index is reindexed.
prefer-repack	Prevent blocking reads/writes to table when rebuilding.