From 91f7a356be30335f924ca6be23560348134c47ed Mon Sep 17 00:00:00 2001
From: Ankit Chaurasia <8670962+sunank200@users.noreply.github.com>
Date: Tue, 9 Aug 2022 15:47:20 +0545
Subject: [PATCH] Add doc string with details about schema and database for
 Postgres (#618)

* Add details about not fetching schema details from airflow connections
---
 src/astro/databases/postgres.py | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/astro/databases/postgres.py b/src/astro/databases/postgres.py
index 2119e7ee4..1eab3d1d8 100644
--- a/src/astro/databases/postgres.py
+++ b/src/astro/databases/postgres.py
@@ -40,7 +40,18 @@ def hook(self) -> PostgresHook:
 
     @property
     def default_metadata(self) -> Metadata:
-        """Fill in default metadata values for table objects addressing postgres databases"""
+        """
+        Fill in default metadata values for table objects addressing Postgres databases.
+
+        Currently, Schema is not being fetched from airflow connection for Postgres because, in Postgres, databases and
+        schema are different concepts: https://www.postgresql.org/docs/current/ddl-schemas.html
+        The PostgresHook only exposes schema:
+        https://airflow.apache.org/docs/apache-airflow-providers-postgres/stable/_api/airflow/providers/postgres/hooks/postgres/index.html
+        However, implementation-wise, it seems that if the PostgresHook receives a schema during initialization,
+        but it uses it as a database in the connection to Postgres:
+        https://github.com/apache/airflow/blob/main/airflow/providers/postgres/hooks/postgres.py#L96
+        """
+        # TODO: Change airflow PostgresHook to fetch database and schema separately
         database = self.hook.get_connection(self.conn_id).schema
         return Metadata(database=database, schema=self.DEFAULT_SCHEMA)