--- a/database/schema/messages.sql	Sat Apr 02 21:15:27 2022 -0400
+++ b/database/schema/messages.sql	Sun Apr 10 17:41:24 2022 -0400
@@ -42,19 +42,14 @@
 -- for patches and mime-attachments
 CREATE TABLE attachments (
 	id bigint		primary key default nextval('next_attachid'),
-	number_in_pr bigint	not null,
 	msgid bigint		not null references messages (id),
+	number_in_msg bigint	not null,
 	mimetype text		not null,
 	body text		not null
 )
 WITHOUT OIDS;
 
--- Create an index for number_in_pr both to enforce uniqueness and
--- to enable lookup.
+-- Create indexes for number_in_pr and number_in_msg both to enforce
+-- uniqueness and to enable lookup.
 CREATE UNIQUE INDEX ON messages (pr, number_in_pr);
--- XXX: does this work?
-CREATE UNIQUE INDEX ON
-  SELECT messages.pr, attachments.number_in_pr
-  FROM messages, attachments
-  WHERE messages.id = attachments.msgid
-;
+CREATE UNIQUE INDEX ON attachments (msgid, number_in_msg);