chore: add docs

api/src/backend/api/rls.py

@@ -78,6 +78,10 @@ class RowLevelSecurityConstraint(models.BaseConstraint):
         policy_queries = ""
         grant_queries = ""
         for statement in self.statements:
+            # SELECT and DELETE uses USING since applies to rows selected
+            # INSERT uses WITH CHECK becauseonly applies in cases where records are being added
+            # UPDATE requires USING and WITH CHECK but if only a USING clause is specified, then that clause will be used for both USING and WITH CHECK cases.
+            # https://www.postgresql.org/docs/current/sql-createpolicy.html
             clause = f"{'WITH CHECK' if statement == 'INSERT' else 'USING'}"
             policy_queries = f"{policy_queries}{self.policy_sql_query.format(statement=statement, clause=clause)}"
             grant_queries = (