:::{php:namespace} Atk4\Data\Persistence\Sql :::
When query is executed by {php:class}Connection or
PDO, it will return an object that
can stream results back to you. The PDO class execution produces a
Doctrine\DBAL\Result object which you can iterate over.
If you are using a custom connection, you then will also need a custom object for streaming results.
The only requirement for such an object is that it has to be a Generator. In most cases developers will expect your generator to return sequence of id => hash representing a key/value result set.
:::{todo} write more :::