[CT-1940] Stand-alone Python module for PostgresColumn (#6773)

.changes/unreleased/Features-20230127-162812.yaml

@@ -0,0 +1,6 @@
+kind: Features
+body: Stand-alone Python module for PostgresColumn
+time: 2023-01-27T16:28:12.212427-08:00
+custom:
+  Author: nssalian
+  Issue: "6772"

plugins/postgres/dbt/adapters/postgres/__init__.py

@@ -1,7 +1,7 @@
 # these are mostly just exports, #noqa them so flake8 will be happy
 from dbt.adapters.postgres.connections import PostgresConnectionManager  # noqa
 from dbt.adapters.postgres.connections import PostgresCredentials
-from dbt.adapters.postgres.relation import PostgresColumn  # noqa
+from dbt.adapters.postgres.column import PostgresColumn  # noqa
 from dbt.adapters.postgres.relation import PostgresRelation  # noqa: F401
 from dbt.adapters.postgres.impl import PostgresAdapter
 

plugins/postgres/dbt/adapters/postgres/column.py

@@ -0,0 +1,12 @@
+from dbt.adapters.base import Column
+
+
+class PostgresColumn(Column):
+    @property
+    def data_type(self):
+        # on postgres, do not convert 'text' or 'varchar' to 'varchar()'
+        if self.dtype.lower() == "text" or (
+            self.dtype.lower() == "character varying" and self.char_size is None
+        ):
+            return self.dtype
+        return super().data_type

plugins/postgres/dbt/adapters/postgres/impl.py

@@ -5,7 +5,7 @@
 from dbt.adapters.base.impl import AdapterConfig
 from dbt.adapters.sql import SQLAdapter
 from dbt.adapters.postgres import PostgresConnectionManager
-from dbt.adapters.postgres import PostgresColumn
+from dbt.adapters.postgres.column import PostgresColumn
 from dbt.adapters.postgres import PostgresRelation
 from dbt.dataclass_schema import dbtClassMixin, ValidationError
 from dbt.exceptions import (

plugins/postgres/dbt/adapters/postgres/relation.py

@@ -1,4 +1,3 @@
-from dbt.adapters.base import Column
 from dataclasses import dataclass
 from dbt.adapters.base.relation import BaseRelation
 from dbt.exceptions import DbtRuntimeError
@@ -21,14 +20,3 @@ def __post_init__(self):
 
     def relation_max_name_length(self):
         return 63
-
-
-class PostgresColumn(Column):
-    @property
-    def data_type(self):
-        # on postgres, do not convert 'text' or 'varchar' to 'varchar()'
-        if self.dtype.lower() == "text" or (
-            self.dtype.lower() == "character varying" and self.char_size is None
-        ):
-            return self.dtype
-        return super().data_type