Oracle with hidden parameters
Oracle has numerous
“hidden” parameters that are used to change the internal behavior of
Oracle. As you may know, all
hidden parameters begin with an underscore character.
states that the hidden parameter should never be changed unless directed
by Oracle technical support, but most expert Oracle DBA’s will commonly
adjust these parameters to improve performance.
These hidden parameters
are used by Oracle to individualize the internal behavior of the
mechanisms for SGA memory management, object management, and hundred of
other internal mechanisms.
Many savvy Oracle
professionals commonly adjust the hidden parameters to improve the overall
performance of their systems. However,
because these are “undocumented” parameters, most Oracle professionals
rely on publications such as Oracle Internals to get insights into the
proper setting for the hidden parameters.
For example, whenever
index contention is experienced (as evidenced by process waits), adjusting
the following parameters may be helpful.
It is easy to display
hidden initialization parameters. Here
is the one that I use:
Connect system/manager as sysdba;
'file', a.ksppity) type,
a.indx = b.indx
a.ksppinm like '\_%' escape '\'