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Changes In 9i To Be Aware Of.

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Written by Administrator
Saturday, 19 July 2008

Some Of The Changes Which Oracle Had stressed in its lower version have been finally implemented in the new release of 9i.The new features in the Oracle9i database of most interest to database administrators. It is written for DBAs experienced * CONNECT INTERNAL and Server Manager are gone. Oracle has been saying for a long time that these would be de supported someday, and now they have.
o Use CONNECT / AS SYSDBA or CONNECT username/password AS SYSDBA instead of CONNECT INTERNAL.
o Use SQL*Plus to startup and shutdown Oracle from the command line instead of Server Manager.
* The Database Creation Assistant is more secure about passwords when a new database is created.
o Most schemas start out locked.
o A Password Management button allows you to set passwords and unlock accounts.
* You can no longer connect as SYS unless you connect AS SYSDBA.
* Security in newly created databases is expected to get tighter in future releases.
o The SYSTEM schema might be eliminated altogether in a future release.
o All initial schemas might start out locked in a future release.
* A "server parameter file" or SPFILE can be used to hold instance parameters instead of an init.ora file.
o The SPFILE is a binary file; you can read it but cannot edit it. (An embedded checksum makes sure you don't make any manual changes!)
o The SPFILE always resides on the server where the database is located. This is a nice feature in that the same SPFILE will get used whether you start the database locally or from a remote machine.
o In 9i RAC systems, one SPFILE holds settings for all instances.
o You can still use an init.ora file instead of an SPFILE, but you should specify PFILE= when starting the instance with an init.ora file. Without PFILE= in the STARTUP command Oracle will look for an SPFILE first, and will only use the init.ora file if it cannot find the SPFILE.
o The ALTER SYSTEM command can be used to change dynamic parameters in memory or update the SPFILE or both. Static parameters can be updated in the SPFILE with the ALTER SYSTEM command. This is a key benefit of the SPFILE over the init.ora file.

o You can create an SPFILE from an init.ora file and vice versa with the CREATE SPFILE and CREATE PFILE commands.
* "System managed undo" or SMU can be used instead of rollback segments.
o With SMU you designate a tablespace as an undo tablespace and Oracle does all of the management.
o Set undo_management = AUTO to use SMU. You'll need to set undo_tablespace to specify which tablespace to use for undo, and you might want to set undo_retention to the number of seconds Oracle should try to wait before overwriting committed undo information. (The default retention is 900 seconds.)
o Set undo_suppress_errors = TRUE to cause Oracle to ignore statements like SET TRANSACTION USE ROLLBACK SEGMENT when SMU is being used.
o Set undo_management = MANUAL (or don't set it at all) in order to use conventional rollback segments.
o The entire database runs in SMU mode or manual mode, but not both at the same time. You must restart the instance to switch from one to the other.
o When you create a new database, it will use SMU out of the box instead of rollback segments.
o Releases 9.0.1.0 and 9.0.1.1 have serious SMU bugs. Users have had their databases corrupted by these bugs. Release 9.0.1.2 was supposed to have fixed these problems.
* Oracle9i "seems like Oracle 8.2" when it comes to migrations (in the words of Michael Alt).
o You go from Oracle8i to Oracle9i by running catalog upgrade scripts or using the Oracle Data Migration Assistant.
o You cannot run the mig utility to go from Oracle8i to Oracle9i.
o The move from Oracle8i to Oracle9i only changes the data dictionary. Data blocks are reformatted as they are used.
o You can go from Oracle 7.3.4 to Oracle9i in one step with the Oracle Data Migration Assistant or mig.
o The move to Oracle9i can take several hours because the entire JVM is rebuilt.