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

<strong>Solution</strong> <strong>Guide</strong> <strong>for</strong> <strong>Migrating</strong> <strong>Oracle</strong> on UNIX to SQL Server on Windows 81Table 5.2 captures some of the relations between tablespaces in <strong>Oracle</strong> and databasesin SQL Server that are not obvious in Figure 5.2.Table 5.2: <strong>Oracle</strong> Tablespaces and SQL Server Functional Equivalents<strong>Oracle</strong>System tablespaceTemporary tablespaceUndo (Rollback) tablespaceOnline Redo log"App Data" tablespace"App Index" tablespaceN/AN/ASQL Servermaster databasetempdb databaseTransaction logTransaction log"App" database —"Data" filegroup"App" database —"Index" filegroupmodel databasemsdb databaseThe following list describes how <strong>Oracle</strong> functionality is implemented in SQL Server:●●●●●Each of the SQL Server databases has its own security structures, such as users,privileges (permissions), and roles.Each of the SQL Server databases has its own administrative roles that bestowprivileges on the database.In SQL Server, the system catalog — which is analogous to the <strong>Oracle</strong> datadictionary — is broken up between the individual databases and the masterdatabase.In SQL Server, each of the databases has its own transaction log files, whichcombine the functions of the <strong>Oracle</strong> online redo logs and rollback segments.The tempdb database provides temporary storage <strong>for</strong> the entire SQL Serverinstance, and the temporary tablespace in <strong>Oracle</strong> is common to the entire <strong>Oracle</strong>instance.Tablespaces and filegroups provide the ability to better distribute data across multiplefiles <strong>for</strong> the purposes of per<strong>for</strong>mance. The grouping also helps ease administration ofbackup and recovery, maintenance, availability, and so on.Each SQL Server database is created with a primary file belonging to the default primaryfilegroup. Optionally, secondary datafiles can be added to the primary filegroup, oradditional filegroups can be created. The location of the files belonging to a database isrecorded in the master database and the primary file <strong>for</strong> the database. Data added toobjects of a filegroup are proportionally filled across all files belonging to the filegroup.A common concern among users when creating SQL Server databases is the lack of themultiplexing feature available in <strong>Oracle</strong> <strong>for</strong> control files and redo logs. This is not aconcern because SQL Server recommends the use of striped and mirrored devices(RAID 0+1) <strong>for</strong> transaction logs to preserve the level of protection against hardwarefailure obtained by log multiplexing. SQL Server recommends using RAID 0+1 <strong>for</strong> alldatabase datafiles. If RAID 0+1 cannot be implemented, at a minimum RAID 5 should beused to provide tolerance <strong>for</strong> hard disk failure. Apart from file systems, SQL Server alsosupports the use of raw partitions.Storage Definition <strong>for</strong> Tables and IndexesIn <strong>Oracle</strong>, the storage definition is used to specify the characteristics of tables andindexes. The following list provides in<strong>for</strong>mation on how these characteristics migrate toSQL Server.