In each scenario, data changes are synchronized automatically, transaction by transaction, or on demand.
在每一种场景中，数据修改都将被自动同步，可以逐一执行同步，也可以按需同步。
3
The server requires these resources on an on-demand basis for a much shorter period than the time span between t1 and t2, which is the total duration of the transaction from the client's perspective.