Oracle初始参数Parameter

SQL> select * from v$version;
BANNER
----------------------------------------------------------------
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bi
PL/SQL Release 10.2.0.4.0 - Production
CORE    10.2.0.4.0      Production
TNS for Linux: Version 10.2.0.4.0 - Production
NLSRTL Version 10.2.0.4.0 - Production

SQL> set linesize 200;
SQL> col name for a30;
SQL> col value for a20;

SQL> select name,value
  2    from v$system_parameter
  3   where name in ('compatible', 'optimizer_features_enable');

NAME                           VALUE
------------------------------ --------------------
compatible                     10.2.0.3.0
optimizer_features_enable      10.2.0.4

/* 10.2.0.4升级完毕后compatible参数默认值为10.2.0.3，不同于optimizer_features_enable */

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Can you kindly define and explain of lock_sga parameter?each flatform(HP, IBM, SUN) recommended value of both parameter
and why it is recommended like that value.

LOCK_SGA locks the entire SGA into physical memory. It is usually advisable to lock the SGA into real (physical) memory, especially if the use of virtual memory would include storing some of the SGA using disk space. This parameter is ignored on platforms that do not support it.

Each platform has its own recommendations and support over the parameter value. Hence you would see differences in the recommendations.

+ lock_sga Only locks the entire SGA into physical memory.

+ It can be set to TRUE as long as you want to lock the entire SGA in the physical memeory and your OS supports it. As for as i know it works in all the platforms.

NOTE:: This parameter is ignored on platforms that do not support it.

+ Windows For sure doesn’t support this parameter.

+ AIX Supports it.

+ LOCK_SGA is not supported on Solaris.

+ On Hp-UX if you have mlock (OS privilege) then LOCK_SGA is not required

+ Linux also supports this parameter

You can also review

Note 577898.1 – ORA-27102 Received At Startup When LOCK_SGA Is Set Although Enough Memory Is Available.

lock_sga: Default value: false.
If set to true, the entire SGA will be locked into physical memory (preventing it from being paged out). This may cause problems on systems with insufficient physical memory.

The parameters (and recommendations) are Unix generic.

The lock_sga parameter (which default AND recommended value is false): If you have sufficient memory on the server, you may consider setting it to true. (Forcing the SGA to be locked in physical memory).
On the other hand, if lock_sga is set to true, and you do not have suffficient memory, the SGA will stay in memory, and force other processe, like server processes to swap, and hence cause performance degradation.

For both the hidden and normal configuration parameters, we do not recommend deviations from the default values, without having detailed information on your specific configruation.

If you look at all Oracle products, options, features and parameters, there are billions of combinations. We do not have a complete catalog over each recommended values for each combiantion.

Diff Hidden Parameter between 10g and 11g

Know more about LOCK_SGA Parameter

Difference between parameter COMPATIBLE and OPTIMIZER_FEATURES_ENABLE

Diff Hidden Parameter between 10g and 11g

Know more about LOCK_SGA Parameter