postgresql/consistent-explicit-outer-join

Why this matters

PostgreSQL accepts `LEFT JOIN` as shorthand for `LEFT OUTER JOIN`. The `always` style spells `OUTER` out so the join shape is unmistakable; the `never` style drops `OUTER`. `INNER JOIN` and `CROSS JOIN` are out of scope.

Examples

SELECT u.id FROM users u LEFT JOIN orders o ON o.user_id = u.id;

SELECT u.id FROM users u RIGHT JOIN orders o ON o.user_id = u.id;

SELECT u.id FROM users u FULL JOIN orders o ON o.user_id = u.id;

SELECT u.id FROM users u LEFT OUTER JOIN orders o ON o.user_id = u.id;

SELECT u.id FROM users u FULL OUTER JOIN orders o ON o.user_id = u.id;

Configure it

// eslint.config.js
import postgresql from "eslint-plugin-postgresql";

export default [
  {
    files: ["**/*.sql"],
    languageOptions: {
      parser: postgresql.configs.recommended.languageOptions.parser,
    },
    plugins: { postgresql },
    rules: {
      "postgresql/consistent-explicit-outer-join": [
        "warn",
        {
          style: "always",
        },
      ],
    },
  },
];

Options

style "always" | "never" default: "always"

`always` (default) requires the explicit `OUTER`. `never` removes it.