Search BC Oracle Sites! Oracle Concepts - initialization parameters init.ora Oracle Tips by Burleson Consulting The Oracle initialization parameter file When the Oracle database is started, one of the first things it needs to do is read the database initialization parameter file.
For installation, no need to create and changes in.init file. Init file is created by installer and is being used instance (database) if there is no pfile. Just run installer and follow the steps to complete the installation.
The parameter file (init.ora) is created by the DBA and defines the overall instance configuration, such as how much memory should be allocated to the instance, the file locations, and internal optimization parameters. Here is a sample init.ora file: dbcachesize = 176000M db2kcachesize = 2048M db16kcachesize = 99000M dbkeepcachesize = 600000M dbrecyclecachesize = 64000M sharedpoolsize = 14000M In this section we will look at the database parameter file in more detail. First we will look at the two different types of parameter files you can use, PFILE?s and SPFILE?s, followed by a look at the parameters that are maintained in the database parameter file. Finally, we will look at how to manage the initialization parameter file. Oracle init.ora Parameters The initialization parameters are a very important part of the Oracle database. Oracle reads the initialization parameter values from either a PFILE or SPFILE as the database is starting.
The parameters tell the Oracle programs how much memory to allocate, where to put files related to the database and the location of existing datafiles. A parameter has a name and a value. In this example, we have a parameter named dbblocksize. This parameter tells oracle how big each individual block in the database is (we discussed blocks in an earlier chapter in this book). In this case, each block is 8192 bytes, or 8k, in size. Dbcachesize=8192 The next parameter you see is the backgrounddumpdest parameter. This parameter defines the location of Oracle trace files (log files) that are created by the Oracle background processes (we talked about the Oracle processes earlier in this book) and the important alert log where database messages reside.
In this case, all files written by Oracle background processes will be in the /u01/oracle/admin/mydb/bdump directory. Backgrounddumpdest=/u01/oracle/admin/mydb/bdump You can find all the Oracle Database parameters at Oracle?s web site, tahiti.oracle.com. Look in the reference guide and you will find them all listed, except for undocumented hidden parameters. These parameters, while changeable, should only be modified with the aid of an experienced DBA or Oracle Technical Support (called MOSC).
Some parameters are dynamic and they can be changed while the database is running. For example, you can decrease the database buffer cache in many cases while the database instance is running with the alter system command: alter system set dbrecoveryfiledestsize=10g; In this example, we dynamically changed the parameter dbrecoveryfiledest to a value of 10 gigabytes (10g). The database will maintain this parameter until it is rebooted, unless a SPFILE is used. We will talk about SPFILE?s shortly. Initialization File Although not normally discussed as a database file a database will not startup without a valid initialization parameter file.
The file is only read at startup and contains the information required to set up the SGA, control file locations, trace and dump file locations and setup parameters for multi-threaded server, parallel query and Oracle Parallel Server. I suggest keeping a copy in a secure place incase yours ever becomes corrupted, deleted or damaged. The Oracle Reference, which is included in the Oracle8 and Oracle8i documentation set, provides descriptions of all initialization parameters. There are also undocumented initialization parameters that allow specialized behaviors to be configured. Both the documented and undocumented initialization parameters are covered in my book?ORACLE8i Administration and Management?
From Wiley and Sons. It should be obvious that the most important file regarding database setup and operation is probably the INIT.ORA, or initialization file. This file contains the assignments for the database initialization parameters. For Oracle7, version 7.3, there are 154 initialization parameters, for Oracle8, version 8.0.5, there are 184. In Oracle8i there are 194. Table 11 is a list of the Oracle8i INIT.ORA parameters, their default values, and descriptions. Note that on your platform there may be more or less than this number of parameters.
NAME VALUE DESCRIPTION O7DICTIONARYACCESSIBILITY TRUE V7 Dictionary accessibility Support (Migration only) ALWAYSANTIJOIN NESTEDLOOPS Always use this anti-join when possible ALWAYSSEMIJOIN standard Always use this semi-join when possible AQTMPROCESSES 0 Number of AQ Time Managers to start AUDITFILEDEST (PD) Destination for audit files AUDITTRAIL NONE Enable system auditing BACKGROUNDCOREDUMP PARTIAL Sets whether SGA is dumped with core file dump, PARTIAL means don't dump SGA.