I really should have added this.

migrations/004.sql

@@ -0,0 +1,8 @@
+-- schema update 2021-02-16
+-- add a table for board-excluded channels
+CREATE TABLE board_exclusions (
+    channel_oid INTEGER PRIMARY KEY,
+    guild_oid INTEGER NOT NULL,
+    FOREIGN KEY (channel_oid) REFERENCES objects(oid),
+    FOREIGN KEY (channel_oid) REFERENCES objects(oid)
+);