Database Reference
In-Depth Information
with any text editor, it is not a file you have to necessarily guard with your life. You can re-create it, as long as you know
what was in it (e.g., you can retrieve that information from the database's alert log, if you have access to that, and
reconstruct your entire
init.ora
parameter file).
We will now examine both types of database startup parameter files (
init.ora
and
SPFILE
) in turn, but before
we do that, let's see what a database parameter file looks like.
What Are Parameters?
In simple terms, a database parameter may be thought of as a key/value pair. You saw an important parameter,
db_name
, in the preceding chapter. The
db_name
parameter was stored as
db_name = ora12c
. The key here is
db_name
and the value is
ora12c.
This is our key/value pair. To see the current value of an instance parameter, you can query
the
V$
view
V$PARAMETER
. Alternatively, in SQL*Plus you can use the
SHOW PARAMETER
command, for example:
EODA@ORA12CR1> select value
2 from v$parameter
3 where name = 'db_block_size'
4 /
VALUE
-------
8192
EODA@ORA12CR1> show parameter db_block_s
NAME TYPE VALUE
------------------------------------ ----------- -------
db_block_size integer 8192
Both outputs show basically the same information, although you can get more information from
V$PARAMETER
(there are many more columns to choose from than displayed in this example). But
SHOW PARAMETER
wins for me in
ease of use and the fact that it “wildcards” automatically. Notice that I typed in only
db_block_s
;
SHOW PARAMETER
adds % to the front and back.
■
all
V$
views and all dictionary views are fully documented in the
Oracle Database Reference
manual. please
regard that manual as the definitive source of what is available in a given view.
Note
If you were to execute the preceding example as a less-privileged user (
EODA
has been granted the
DBA
role for
purposes of this topic), you would see instead:
EODA@ORA12CR1> connect scott/tiger
Connected.
SCOTT@ORA12CR1> select value
2 from v$parameter
3 where name = 'db_block_size'
4 /
from v$parameter
*
