[CR] Place comment on column rather than in source

Allows schema exploration tools to see the comment.  This will
hopefully make online exploration of databases at different revisions
easier.


Former-commit-id: f82623cd4ad97201f3f664481b6b5b11f2576f67

ddl/000002_retention.up.sql

@@ -1,7 +1,10 @@
--- Set before deleting an object to indicate it is going to be
--- removed by an AWS S3 batch operation and cannot be used for new
--- dedupes.
 ALTER TABLE catalog_object_dedup
     DROP CONSTRAINT IF EXISTS catalog_object_dedup_pk,
     ADD COLUMN IF NOT EXISTS deleting boolean DEFAULT false NOT NULL,
     ADD CONSTRAINT catalog_object_dedup_pk PRIMARY KEY (repository_id, dedup_id, deleting);
+
+COMMENT ON COLUMN catalog_object_dedup.deleting IS $$
+Set before deleting an object to indicate it is going to be
+removed by an AWS S3 batch operation and cannot be used for new
+dedupes.
+$$;