#Primary keys

int and string primary keys are both supported. Auto-incrementing bigint (the Laravel default), UUIDv7 / ULID / time-ordered string keys, and any other monotonically-ordered identifier work end to end. The package's tree mutation, repair, aggregate maintenance, and queued fix-aggregates job all flow the model's PK type through without narrowing to int.

#Choosing the column type

Choose the parent_id column type at migration time via the parentIdType argument to the nestedSet() macro:

Schema::create('categories', function (Blueprint $table): void {
    $table->uuid('id')->primary();
    $table->string('name');
    $table->nestedSet(parentIdType: 'uuid');     // matches the PK type
});

Accepted values: 'bigint' (default), 'uuid', 'ulid', 'string', or a closure function (Blueprint $table, string $column): void { … } for custom shapes (nanoid, fixed-width char, FK constraints, etc.). Composite primary keys are not supported.

#Monotonicity matters for chunked repair

Chunked aggregate repair (fixAggregates(chunkSize: …) and the queued FixAggregatesJob) walks rows with WHERE id > ? ORDER BY id LIMIT N, so it relies on the PK being lexicographically monotonic. UUIDv7, ULID, bigint auto-increment, and ascending strings all qualify. UUIDv4, nanoid (random by default), or clock-rollback UUIDv1 will silently skip rows under the chunked path — use the unchunked fixAggregates($anchor) call on those models instead.