When very large tables are out of sync on the target and Compare is not a suitable sync option, it requires a set of coordinated steps to bring them in sync with the source tables. This is especially true if the downtime on the source table is not acceptable and the sync needs to be done in conjunction with ongoing replication. It is good to know that the Copy command of SharePlex provides a convenient way to resync such tables.
The Copy uses Oracle Export/Import utility and carries out a number of operations in the background which are transparent to the user. All the while users can keep making changes to the source table though the target table is unavailable to users until Copy finishes. Though the Copy is fast, the time it takes is proportional to the size of the table being synchronized. Essentially the Copy takes an Export dump of the source table in read consistent mode and the Import utility on target then recreates the target table. Though the Copy locks the source table albeit briefly, users will not feel any interruption. If for some reason it cannot acquire a lock on a busy table, it keeps trying multiple times without running into errors right away. It also suspends the posting to the target table at the point where the read consistent Export was launched and once the Import on the target recreates the target table, the posting is resumed. It is extremely convenient to users. Though it is possible to manually use Export/Import utility to sync tables, the steps involved are cumbersome and prone to user errors.
Copy also comes handy when setting up replication for the first time. It allows multiple tables to be synchronized with a single command. This makes it convenient for the users to start replication and sync the target tables at the same time. Without this utility users have to adopt other means to do the first time sync of the target tables when starting a brand new replication.
For further details on the Copy command please refer to SharePlex Reference Guide for SharePlex version 8.6.5.
