0.2.59 - Settings save fixes

server/internal/store/preferences.go

@@ -171,10 +171,18 @@ func (s *Store) SetUserPreferences(
 	// Pruned here rather than on a schedule: this is the only writer, so it is the only
 	// place the table can grow, and the acks of a revision nobody can see any more are
 	// dead weight with it.
+	//
+	// The cutoff is worked out in Go rather than as `$2 - $3` in the statement. Postgres
+	// has to infer a type for every placeholder, and two of them either side of an
+	// operator give it nothing to infer from — it answers `operator is not unique:
+	// unknown - unknown`, which failed the whole transaction and returned 500 to every
+	// television trying to save a setting. Arithmetic on two parameters belongs on this
+	// side of the wire.
+	pruneBelow := next.Revision - preferenceHistoryLimit
 	if _, err := tx.Exec(ctx, `
 		DELETE FROM user_preference_revisions
-		WHERE emby_user_id = $1 AND revision <= $2 - $3`,
-		userID, next.Revision, preferenceHistoryLimit,
+		WHERE emby_user_id = $1 AND revision <= $2`,
+		userID, pruneBelow,
 	); err != nil {
 		return UserPreferences{}, fmt.Errorf("store: prune preference history: %w", err)
 	}
@@ -183,13 +191,13 @@ func (s *Store) SetUserPreferences(
 	// described as "on revision 12" rather than as one that has never checked in.
 	if _, err := tx.Exec(ctx, `
 		DELETE FROM user_preference_acks stale
-		WHERE stale.emby_user_id = $1 AND stale.revision <= $2 - $3
+		WHERE stale.emby_user_id = $1 AND stale.revision <= $2
 		  AND EXISTS (
 			SELECT 1 FROM user_preference_acks newer
 			WHERE newer.emby_user_id = stale.emby_user_id
 			  AND newer.device_id = stale.device_id
 			  AND newer.revision > stale.revision)`,
-		userID, next.Revision, preferenceHistoryLimit,
+		userID, pruneBelow,
 	); err != nil {
 		return UserPreferences{}, fmt.Errorf("store: prune preference acks: %w", err)
 	}