1CREATE TABLE "channel_message_mentions" (
 2    "message_id" INTEGER NOT NULL REFERENCES channel_messages (id) ON DELETE CASCADE,
 3    "start_offset" INTEGER NOT NULL,
 4    "end_offset" INTEGER NOT NULL,
 5    "user_id" INTEGER NOT NULL REFERENCES users (id) ON DELETE CASCADE,
 6    PRIMARY KEY(message_id, start_offset)
 7);
 8
 9-- We use 'on conflict update' with this index, so it should be per-user.
10CREATE UNIQUE INDEX "index_channel_messages_on_sender_id_nonce" ON "channel_messages" ("sender_id", "nonce");
11DROP INDEX "index_channel_messages_on_nonce";