postgresql/prefer-exists-over-in-subquery

Why this matters

`column IN (subquery)` returns NULL whenever the subquery yields a NULL row, which silently filters every row from the outer query. `EXISTS (subquery)` returns a clean boolean and is typically planned more cheaply too. Literal `IN` lists (`x IN (1, 2, 3)`) are out of scope.

Examples

SELECT * FROM t WHERE x IN (SELECT id FROM other);

SELECT * FROM t WHERE x = ANY (SELECT id FROM other);

SELECT * FROM t WHERE EXISTS (SELECT 1 FROM other WHERE other.id = t.x);

SELECT * FROM t WHERE x IN (1, 2, 3); -- literal list is out of scope

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/prefer-exists-over-in-subquery": "warn",
    },
  },
];

Options

This rule has no options.