Sybase DC38133-01-0902-01 manual Designing to avoid referential integrity errors

Chapter 7. SQL Remote Design for Adaptive Server Anywhere

SQL Remote resolves conflicts; you may just want to report the conflicts by storing them in a table. In this way, you can look at the conflict table to see what, if any, conflicts have occurred, and if necessary take action to resolve the conflicts.

Designing to avoid referential integrity errors

The tables in a relational database are related through foreign key references. The referential integrity constraints applied as a consequence of these references ensure that the database remains consistent. If you wish to replicate only a part of a database, there are potential problems with the referential integrity of the replicated database.

	By paying attention to referential integrity issues while designing
	publications you can avoid these problems. This section describes some of
	the more common integrity problems and suggests ways to avoid them.
Unreplicated referenced The sales publication described in “Publishing whole tables” on page 93
table errors	includes the sales_order table:

CREATE PUBLICATION pub_sales ( TABLE customer,

TABLE sales_order, TABLE sales_order_items, TABLE product

)

The sales_order table has a foreign key to the employee table. The id of the sales rep is a foreign key in the sales_order table referencing the primary key of the employee table. However, the employee table is not included in the publication.

If the publication is created in this manner, new sales orders would fail to replicate unless the remote database has the foreign key reference removed from the sales_order table.

If you use the extraction utility to create the remote databases, the foreign key reference is automatically excluded from the remote database, and this problem is avoided. However, there is no constraint in the database to prevent an invalid value from being inserted into the sales_rep_id column of the sales_order table, and if this happens the INSERT will fail at the consolidated database. To avoid this problem, you can include the employee table (or at least its primary key) in the publication.

Designing triggers to avoid errors

Actions performed by triggers are not replicated: triggers that exist at one database in a SQL Remote setup are assumed by the replication procedure to

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