Solution Guide for Migrating Oracle on UNIX to SQL Server - Willy .Net

170 Developing: Databases — Unit Testing the Migrationsignificantly. You must verify that only authenticated, authorized users have access to theobjects in the database. You must also verify that <strong>Oracle</strong> users and roles have beencorrectly mapped to SQL Server users and roles, and that all objects in the databasehave the appropriate access rights granted to them.Validate DataThe existence of indexes and constraints during data migration adversely affects theper<strong>for</strong>mance of the data migration. The firing of triggers can corrupt the data and produceundesirable effects. There<strong>for</strong>e, these objects have to be disabled or dropped. A negativeaspect of these actions is that data is not checked <strong>for</strong> correctness or completenessduring the migration and has to be validated after the migration. No special plans areneeded <strong>for</strong> validating data integrity. The database itself checks the integrity of the datawhen the constraints are enabled using the WITH CHECK clause. For more in<strong>for</strong>mationon check constraints in SQL Server, refer tohttp://msdn.microsoft.com/library/default.asp?url=/library/en-us/tsqlref/ts_aa-az_3ied.asp.The two types of tests that have to be per<strong>for</strong>med to validate the data are discussed in the"Validating the Data Migration" section in Chapter 8.Note One of the common risks involved in data migration is the lack of a proper orcomplete set of constraints in the database. In many applications, the constraints arebuilt into the application. In such cases, the development team will have to be involvedin constructing SQL-based tests to verify data integrity by identifying such rules in theapplication.Validate the MigrationAfter data migration is complete, tests have to be per<strong>for</strong>med on the database as a whole.Testing should cover the database architecture, database objects, data, and users. Inaddition, the database connectivity, security, and per<strong>for</strong>mance have to be tested. Forin<strong>for</strong>mation on client connectivity to the database, refer tohttp://msdn.microsoft.com/library/default.asp?url=/library/enus/adminsql/ad_1_client_5er7.asp.A discussion of the security architecture in <strong>Oracle</strong> andSQL Server is available in Appendix A: "SQL Server <strong>for</strong> <strong>Oracle</strong> Professionals." AppendixB: "Getting the Best out of SQL Server 2000 and Windows" contains several referenceson SQL Server per<strong>for</strong>mance.While in smaller databases the data migration validation can be exhaustive, in very largedatabases, some simpler tests (such as counts using various groupings) may be used.The following checks are recommended:● Develop group functions based on type of data.For example, a business-related check can be implemented by calculating the sumof the balances in all accounts.● Develop group functions based on time.● Check <strong>for</strong> record counts.● Use the application to compare the summary reports.● Check <strong>for</strong> ad-hoc control totals.For example, after ledger data of a financial application has been migrated, addingup the account numbers in that ledger has no business validity. However, this adhoccontrol total could reveal if all the data in the row has been migratedsuccessfully.