Arg represents an argument to both a postgres query and the golang shim which wraps that query.

ColMeta contains metadata about postgres table columns such column names, types, nullability, default...

PgTableInfo contains metadata about a postgres table that we get directly from postgres.

RefMeta contains metadata for a reference between two tables (a foreign key relationship).

Resolver knows how to query postgres for metadata about the database schema.

This genctx duplicates info already stored in the Meta member, but it is a nice quality of life improvement to have some of the really commonly refered to data bubbled up to the top level.

TableMeta contains information about a single table required for code generation.