V02 of the package DDL: the subscription table ADR-0007, section 6 fixes, named by StatifierRouter.Config.table/2 under the host's table prefix and created in the host's Postgres schema when one is set.

subscriptions (ADR-0007, section 6): one row per live source invocation, written by StatifierRouter.subscribe/3 and deleted by StatifierRouter.cancel/2.

Every column is null: false, the shape V01's address table already uses for everything but its terminal timestamp: a subscription with no key is the refusal ADR-0007, section 6 names rather than a row.

Index: the unique <table>_execution_id_binding_id_invoke_id_index on (execution_id, binding_id, invoke_id). That triple is the identity ADR-0007, section 6 asks the row to distinguish - "two invocations of the same binding in one execution do not cancel each other" - and its leading column is the one StatifierRouter.SourceInvoke reads a row back by, since the engine's cancellation carries an invoke_id and an execution and no binding.

Under the default table prefix that name is 70 bytes, past the 63 Postgres keeps, so Postgres creates the index under its first 63 bytes. This version still builds it that way, so a database that already ran it and a fresh one hold the same index; StatifierRouter.Migrations.V03 renames it to <table>_invocation_index.

The table above is the layout with no layout option set. The StatifierRouter.Migrations layout options reshape it only as this version creates it, on the same terms as V01's tables: the :leading_columns immediately after id, inserted_at following them under timestamps_position: :leading, and each text column :column_collations names declared with its collation. Its id is the host repo's implicit primary key, as V01's is, or under the :primary_key option the type and default that option names. A table V01 already created is not touched.

A host that has already run V01 reaches this version with StatifierRouter.Migrations.up(from: 2): from: names the first version the host has not run and the walk includes it.