Sybase 12.4.2 manual Importing data by replication, 226

Importing data by replication

Space for deletions When you use the DELETE statement, you may need to add space to your database, due to the way Adaptive Server IQ stores versions of data pages. For details, see “Overlapping versions and deletions”.

When you use DROP TABLE or TRUNCATE TABLE, you do not need to add space, as no extra version pages are needed.

Importing data by replication

If you need to update your IQ data frequently from an Adaptive Server Enterprise database, you may want to consider setting up a replication environment. In this environment, you can use the Sybase Distribution Director to automate the process of replicating data from an Adaptive Server Enterprise database into an Adaptive Server IQ database.

Distribution Director establishes a two-phase process in which transactions that occur on the source database—the Adaptive Server Enterprise database— are repeated on the Adaptive Server IQ database. To make this process work, you need:

•An operating Replication Server system, which includes a special database called the Replication Server System Database (RSSD). This database contains replication definitions that describe the transactions in the source database, and how they should be replicated to the replicate databases.

•A specially prepared replicate database on an Adaptive Server Enterprise database. This replicate database serves as a staging area for the migration into your IQ database.

•Your IQ database set up with the appropriate tables for the data to be replicated.

Here is a summary of how it works:

1In Phase 1, the Replication Server replicates transactions from the source database to the RSSD on a continuous basis.

2In Phase 2, the Adaptive Server IQ staging migration is executed, to transfer the replicated transactions from the RSSD into the IQ database.

This two-phase approach overcomes differences between the way Adaptive Server Enterprise and Adaptive Server IQ store and update data. It also allows you to schedule insertions into your database for lower usage periods, and avoids conflicts with other insertions or loads to the same tables.

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