banAlterDomainWithAddConstraint¶

Group safety · Migrations only · Since Unreleased
Diagnostic lint/banAlterDomainWithAddConstraint

Sources: inspired by squawk/ban-alter-domain-with-add-constraint

Description¶

Adding a constraint to a domain has poor support for online migrations.

ALTER DOMAIN ... ADD CONSTRAINT validates every column that uses the domain, across all tables, while holding locks on them. Postgres can't reason about arbitrary domain constraints the way it can about simple column types.

Put the constraint on the columns directly instead.

Examples¶

Invalid¶

alter domain positive_int add constraint positive_int_check check (value > 0);

code-block.sql:1:1 lint/banAlterDomainWithAddConstraint ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! Adding a constraint to a domain has poor support for online migrations.

  > 1 │ alter domain positive_int add constraint positive_int_check check (value > 0);
      │ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    2 │ 

  i Postgres validates every column that uses the domain, across all tables.

  i Use table and column constraints instead.

How to configure¶

{
  "linter": {
    "rules": {
      "banAlterDomainWithAddConstraint": "error"
    }
  }
}

How to suppress¶

Suppress this diagnostic with a comment:

-- pgls-ignore banAlterDomainWithAddConstraint