docs/reference/rules/disallow-unique-constraint.md
Diagnostic Category: lint/safety/disallowUniqueConstraint
Since: vnext
Sources:
Disallow adding a UNIQUE constraint without using an existing index.
Adding a UNIQUE constraint requires an ACCESS EXCLUSIVE lock, which blocks all reads and writes to the table. Instead, create a unique index concurrently and then add the constraint using that index.
ALTER TABLE table_name ADD CONSTRAINT field_name_constraint UNIQUE (field_name);
code-block.sql:1:1 lint/safety/disallowUniqueConstraint ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
× Adding a UNIQUE constraint requires an ACCESS EXCLUSIVE lock.
> 1 │ ALTER TABLE table_name ADD CONSTRAINT field_name_constraint UNIQUE (field_name);
│ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
2 │
i Create a unique index CONCURRENTLY and then add the constraint using that index.
ALTER TABLE foo ADD COLUMN bar text UNIQUE;
code-block.sql:1:1 lint/safety/disallowUniqueConstraint ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
× Adding a UNIQUE constraint requires an ACCESS EXCLUSIVE lock.
> 1 │ ALTER TABLE foo ADD COLUMN bar text UNIQUE;
│ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
2 │
i Create a unique index CONCURRENTLY and then add the constraint using that index.
CREATE UNIQUE INDEX CONCURRENTLY dist_id_temp_idx ON distributors (dist_id);
ALTER TABLE distributors DROP CONSTRAINT distributors_pkey,
ADD CONSTRAINT distributors_pkey PRIMARY KEY USING INDEX dist_id_temp_idx;
{
"linter": {
"rules": {
"safety": {
"disallowUniqueConstraint": "error"
}
}
}
}