SQL: Allow NULL values for annotation.last_revision_id

See metabrainz/bookbrainz-data-js#320

sql/migrations/2024-07-17-annotation-revision-id/down.sql

@@ -0,0 +1,6 @@
+
+BEGIN;
+
+ALTER TABLE bookbrainz.annotation ALTER COLUMN last_revision_id SET NOT NULL;
+
+COMMIT;

sql/migrations/2024-07-17-annotation-revision-id/up.sql

@@ -0,0 +1,7 @@
+-- Allow NULL values for annotation.last_revision_id (foreing key to revision table)
+-- so that we can use annotations for entities pending import, which do not have revisions.
+BEGIN;
+
+ALTER TABLE bookbrainz.annotation ALTER COLUMN last_revision_id DROP NOT NULL;
+
+COMMIT;

sql/schemas/bookbrainz.sql

@@ -453,7 +453,7 @@ ALTER TABLE bookbrainz.work_revision ADD FOREIGN KEY (data_id) REFERENCES bookbr
 CREATE TABLE bookbrainz.annotation (
 	id SERIAL PRIMARY KEY,
 	content TEXT NOT NULL,
-	last_revision_id INT NOT NULL
+	last_revision_id INT
 );
 ALTER TABLE bookbrainz.annotation ADD FOREIGN KEY (last_revision_id) REFERENCES bookbrainz.revision (id);
 ALTER TABLE bookbrainz.author_data ADD FOREIGN KEY (annotation_id) REFERENCES bookbrainz.annotation (id);