A local update application allows clients at a remote site to see the updates they have entered before the replication system returns them from the primary site. For example, if a customer account is updated at a remote site, clients at the site can see the results of the transaction even if the primary site is not accessible.
Local updates can be performed by using a pending updates table. For each replicated table, a corresponding local table contains provisional updates—updates that have been submitted to the primary site, but that have not been returned through the replication system. Client applications update the pending transactions table and, at the same time, send a request function to the primary site. See “An example using a local pending table” for information on implementing this type of application.
When the update succeeds against the primary copy, it is distributed to remote sites, including the site where the transaction originated. You can create a function string or replicated stored procedure to update the replicated table and delete local updates from the pending table. This makes it possible for client applications to know which transactions have been confirmed and which are pending.
