| Top 10 init.ora parameters Some
of the init.ora parameters are really critical in the performance of a
database. Here we are discussing about the top 10 init.ora parameters.
These are the important parameters and should be taken care while creating
or working on databases.
- DB_NAME
- DB_DOMAIN
- CONTROL_FILES
- DB_BLOCK_SIZE
- DB_BLOCK_BUFFERS
- LOG_BUFFER
- SHARED_POOL_SIZE
- SORT_AREA_SIZE
- PROCESSES
- ROLLBACK_SEGMENTS
DB_NAME : This parameter specifies the local name of the
database. This is an optional parameter but Oracle recommends to set this
parameter before you create the database. it must be set as text string up
to eight characters. The value which is provided to this parameter will be
recorded in control file, datafiles and redo log files during the database
creation. Default value for this parameter is NULL.
For Example:
DB_NAME=
prod
prod is the name of
the database.
DB_DOMAIN: DB_DOMAIN Specifies the logical location (
Domain) with in the network. The combination of DB_NAME and DB_DOMAIN
parameters should be unique with in the network. This parameter is
important when you are going to use distributed database system.
For
Example:
DB_DOMAIN=test.com
test.com is the domain name and global
database name can recognize by prod.test.com where prod is the database
name.
CONTROL_FILES: This parameter specifies the name of the control
files. when database is created, Oracle creates control file according to
the path which specifies in the init.ora file. If no value is assigned to
this parameter then Oracle create this parameter in the default location.
Eight different files can be assigned to this parameter but it is
recommended to have three different control files on different disks.
DB_BLOCK_SIZE: This parameter specifies the data block size. The size of
the block should be multiple of the block size of OS. For example it can
be 2k, 4k up to 32k in Oracle 8i but the maximum value is OS- Dependent.
DB_BLOCK_BUFFERS: This is very critical performance parameter that
determines the number of buffers in the buffer cache in the System Global
Area. Importance of this parameter is more because , data block size
cannot be changed after database is created. In that case this parameter
can be used to tune the size of data buffer. Buffer cache size can be
calculated by the following formula.
Data buffer Cache size=DB_BLOCK_SIZE
x DB_BLOCK_BUFFERS
LOG_BUFFER: This parameter specifies the size of redo
log buffer. It is buffer for uncommitted transactions in the memory. The
default setting for this parameter is four times the maximum data block
size for the host Operating System.
SHARED_POOL_SIZE: This parameter
specifies the size of shared memory for the instance. This is important
parameter for memory tuning and can be altered after database creation
SORT_AREA_SIZE: This specifies the size of memory used for sorting and
merging of data. This represents the area that can be used by each user
process to perform sorting and merging of data.
PROCESSES: This parameter
determines the maximum number of OS process that can be connected to
database at the same time. The value for this parameter must include 5 for
background process. i.e. if you want to have 20 users then you must have
it 25.
ROLLBACK_SEGMENTS: This parameter specifies the list of rollback
segments for an Oracle Instance. Performance is also gets affected by the
size of Rollback Segment. This should be larger enough to hold the
rollback entries of the transaction | 
