PostgreslikeAdapter base class

[norton120]

why?

source adapters need to be WAY more dry and intuitive before we ask for source contributions. this could largely be handled by creating a PostgreslikeAdapter base class that abstracts most of the statement logic to a common parent class.

‌

who it will benefit?

Anyone looking to contribute a new source adapter class. Us, when we do any work on the existing snowflake adapter.

how you might implement it?

Migrate to a parent class for postgres-like implementations. these can be overridden on a statement level as needed, but often there will only need to be a handful of partials defined for a new adapter.

‌

[Issue created by ethanknox: 2020-01-31]