Constraints — ASL

Field constraints

email: str {
  constraint exclusive;          # UNIQUE
  constraint min_length(5);
  constraint max_length(100);
};

id: uuid {
  constraint pk;                 # PRIMARY KEY
  constraint exclusive;          # UNIQUE
};

min_length(n) and max_length(n) apply to string columns and are emitted as a named CHECK (char_length("col") >= n) / <= n. All field-level constraints carry a deterministic name — enum and length CHECKs (chk_<table>_<column>_<kind>), single-column UNIQUE (uq_<table>_<column>), primary keys (pk_<table>), and foreign keys (fk_<table>_<column>). That same name is used both inside CREATE TABLE and in any later ALTER TABLE ... ADD/DROP CONSTRAINT, so a constraint created with a table can be dropped by name on a schema change or rollback.

For constraints that span multiple columns, see type-level constraints.