Send channel as prefix for compat clients

scnserver/db/impl/primary/compat.go

@@ -155,3 +155,26 @@ func (db *Database) SetAck(ctx TxContext, userid models.UserID, msgid models.Mes
 
 	return nil
 }
+
+func (db *Database) IsCompatClient(ctx TxContext, clientid models.ClientID) (bool, error) {
+	tx, err := ctx.GetOrCreateTransaction(db)
+	if err != nil {
+		return false, err
+	}
+
+	rows, err := tx.Query(ctx, "SELECT * FROM compat_clients WHERE client_id = :id LIMIT 1", sq.PP{
+		"id": clientid,
+	})
+	if err != nil {
+		return false, err
+	}
+
+	res := rows.Next()
+
+	err = rows.Close()
+	if err != nil {
+		return false, err
+	}
+
+	return res, nil
+}

scnserver/db/impl/primary/schema/schema_3.ddl

@@ -214,6 +214,13 @@ CREATE UNIQUE INDEX "idx_compatacks_messageid"        ON compat_acks (message_id
 CREATE UNIQUE INDEX "idx_compatacks_userid_messageid" ON compat_acks (user_id, message_id);
 
 
+CREATE TABLE compat_clients
+(
+    client_id         TEXT    NOT NULL
+) STRICT;
+CREATE UNIQUE INDEX "idx_compatclient_clientid" ON compat_clients (client_id);
+
+
 CREATE TABLE `meta`
 (
     meta_key     TEXT       NOT NULL,