Comments on: A simple interview question http://blog.tanelpoder.com/2007/10/20/a-simple-interview-question/ Oracle troubleshooting, internals and performance tuning Thu, 11 Mar 2010 20:28:36 +0000 http://wordpress.org/?v=2.9.2 hourly 1 By: Amir Hameed http://blog.tanelpoder.com/2007/10/20/a-simple-interview-question/comment-page-1/#comment-212 Amir Hameed Tue, 18 Dec 2007 17:37:27 +0000 http://blog.tanelpoder.com/2007/10/20/a-simple-interview-question/#comment-212 Hi Tanel, I have noticed that if I log into a running Oracle instance and run "show parameter db_cache_size", Oracle only displays the non-doubles undercore value. But if I stopped the instance, start it again and by staying in the same session, I issue the same command, Oracle will show the double underscore values: --- SQL> conn / as sysdba Connected. SQL> show parameter db_cache_size NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ db_cache_size big integer 1G SQL> shutdown immediate Database closed. Database dismounted. SQL> SQL> startup ORACLE instance started. Total System Global Area 1.0737E+10 bytes Fixed Size 2046784 bytes Variable Size 7314867392 bytes Database Buffers 3405774848 bytes Redo Buffers 14729216 bytes Database mounted. Database opened. SQL> show parameter db_cache_size NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ __db_cache_size big integer 3248M db_cache_size big integer 1G Somehow, the session that brings up an Oracle instance pulls these values from regareless of whether SPFILE is used or not (I have tested both scenarios). Hi Tanel,
I have noticed that if I log into a running Oracle instance and run “show parameter db_cache_size”, Oracle only displays the non-doubles undercore value. But if I stopped the instance, start it again and by staying in the same session, I issue the same command, Oracle will show the double underscore values:
—
SQL> conn / as sysdba
Connected.
SQL> show parameter db_cache_size

NAME TYPE VALUE
———————————— ———– ——————————
db_cache_size big integer 1G

SQL> shutdown immediate
Database closed.
Database dismounted.
SQL>
SQL> startup
ORACLE instance started.

Total System Global Area 1.0737E+10 bytes
Fixed Size 2046784 bytes
Variable Size 7314867392 bytes
Database Buffers 3405774848 bytes
Redo Buffers 14729216 bytes
Database mounted.
Database opened.
SQL> show parameter db_cache_size

NAME TYPE VALUE
———————————— ———– ——————————
__db_cache_size big integer 3248M
db_cache_size big integer 1G

Somehow, the session that brings up an Oracle instance pulls these values from regareless of whether SPFILE is used or not (I have tested both scenarios).

]]> By: TedC http://blog.tanelpoder.com/2007/10/20/a-simple-interview-question/comment-page-1/#comment-211 TedC Wed, 24 Oct 2007 13:25:09 +0000 http://blog.tanelpoder.com/2007/10/20/a-simple-interview-question/#comment-211 This is exactly the reason why so many developers and others find Oracle so annoying. Why have multiple layers to get to an answer and why obfuscate something so simple. "Hey Oracle" call it what it is.... Excellent post. This is exactly the reason why so many developers and others find Oracle so annoying. Why have multiple layers to get to an answer and why obfuscate something so simple. “Hey Oracle” call it what it is…. Excellent post.

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