Track my own custom metadata on Postgres tables and columns
Usually the most portable way of doing this is to have your own metadata table, something like:

create table meta(
  table_name text not null,
  column_name text not null,
  attribute_name text not null,
  attribute_value text not null,
  primary key (table_name, column_name, attribute_name)
);



This approach works with any database
Access to metadata is done by standard SQL
Migration and backup is very easy
The attribute_value can be anything, you can declare it as byte[], text, json, jsonb, whatever you want...