Abstract: A system, comprising a first client, a second client and a server, wherein the first client is configured to send a first update instruction to the server; the server is configured to transform the first update instruction into a second update instruction on the basis of catalog information, and notify the second update instruction to the second client, wherein the second update instruction indicates a set of partial update operations, which are associated to second data stored by the second client using a second schema; and the second client is configured to apply the second update instruction to the stored second data. In this manner, the second client and the first client can keep consistent data in the second schema and the first schema respectively.