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Oracle Configuration.

233 - Resize or Recreate Online Redo log

One of the best ways to resize or recreate online redo log files and keep the current sequence is to perform it online. In this example,
we will resize all online redo logs from 100MB to 300MB while the database is running and use SQL*Plus to drop/recreate them in stages.

1. Check the logs information, files and status.

SQL> SELECT a.group#, a.member, b.bytes FROM v$logfile a, v$log b WHERE a.group# = b.group#;

227 - Oracle Memory Usage & Health Check

In terms of memory configuration on DB, you check your applications aspect.

* Sort and Hash join --> Need to increase PGA.
* Multiple & Variety SQLs --> Need to increase SGA.

< SGA >

1. Check if Buffer hit ratio > 95% or not


SGA_TARGET is a database initialization parameter (introduced in Oracle 10g) that can be used for automatic SGA memory sizing.
This feature is known as  Automatic Shared Memory Management (ASMM).

By using one parameter we don't need to use all other SGA parameters like.

* DB_CACHE_SIZE (DEFAULT buffer pool)
* SHARED_POOL_SIZE (Shared Pool)
* LARGE_POOL_SIZE (Large Pool)
* JAVA_POOL_SIZE (Java Pool)

1. Check STATISTICS_LEVEL    --  Get DB Statistics

218 - APP-FND-00500 noprint

Oracle EBS has the following error when you print out noprint with more than 0 copy.

217 - mod_ossl: Child could not open SSLMutex lockfile

Intermittently, over a period of several days or weeks, HTTP Server will suddenly lock up - neither processing connections, nor rejecting them. 
The error_log may contain thousands (typically one per user click) of the following entries :

195 - Oracle SGA Memory

The SGA is a chunk of memory that is allocated by an Oracle Instance (during the nomount stage) and is shared among Oracle processes,
hence the name. It contains all sorts of information about the instance and the database that is needed to operate.

Variable size:
This is combination of shared pool, Java pool and Large Pool

Fixed portion :
The size of the fixed portion is constant for a release and a plattform of Oracle, that is, it cannot be changed through any means
such as altering the initialization parameters.

184 - Oracle identifiers

SID (System Identifier) :

A SID (almost) uniquely identifies an instance. Actually, $ORACLE_HOME, $ORACLE_SID and
$HOSTNAME identify an instance uniquely.

Global database name :

A database is uniquely identified by a global database name.
Usually, the global database name must be consisting of db_domain and db_name.

Database Name :

179 - pfile vs sfile in Oracle

  • pfile

Specify the name of the text parameter file you want to create. If you do not specify pfile_name, Oracle Database uses the platform-specific
default initialization parameter file name.

  • sfile

Specify the name of the binary server parameter from which you want to create a text file. If you specify spfile_name, then the file must exist on
the server. If the file does not reside in the default directory for server parameter files on your operating system, then you must specify the full path.

168 - Change Oracle DB Chracter Set

If you want to change from WE8MSWIN1252 to AL32UTF8. Check the NLS parameters first.


The syntax of the ALTER DATABASE CHARACTER SET statement is as follows:

165 - Alter Oracle for autoextend on

Recommend using locally-managed tablespaces (extent management local) and automatic segment storage management
(segment space management auto).

The following command script will alter a data file to "autoextend on" removing the potential for "object cannot extend"
and "unable to allocate extent" errors and placing the onus on the DBA to monitor the OS file system to have enough
room for data file growth.


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by Dr. Radut