| What is a Fixed SGA? [message #63419] |
Mon, 04 October 2004 05:28  |
BhavinShah
Messages: 105
Registered: February 2004
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Senior Member |
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Hi, Friends
What is a Fixed SGA ? When Database is started it shows bytes of Fixed SGA . What is a content of Fixed SGA ?
Bhavin
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| Re: What is a Fixed SGA? [message #63428 is a reply to message #63419] |
Mon, 04 October 2004 11:55  |
croK
Messages: 170
Registered: April 2002
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Senior Member |
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Fixed Size
- Contains general information about the state of the database and the instance, which the background processes need to access.
- No user data is stored here.
- This area is usually less than 100k in size.
That was then, prior to 9i.
In Oracle9i, the SGA can be configured as in prior releases to be static, or can now be dynamically configured. The size of the dynamic SGA is determined by the values of the following database initialization parameters: DB_BLOCK_SIZE, DB_CACHE_SIZE, SHARED_POOL_SIZE, and LOG_BUFFER.
Beginning with Oracle9i, the SGA infrastructure is dynamic. This means that the following primary parameters used to size the SGA can be changed while the instance is running:
Buffer cache ( DB_CACHE_SIZE) -- the size in bytes of the cache of standard blocks
Shared pool ( SHARED _POOL_SIZE) -- the size in bytes of the area devoted to shared SQL and PL/SQL statements
Large pool (LARGE_POOL_SIZE) (default is 0 bytes) -- the size in bytes of the large pool used in shared server systems for session memory, parallel execution for message buffers, and by backup and processes for disk I/O buffers.
Best luck.
Oracle Consultant and remote DBA for hire.
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| Re: What is a Fixed SGA? [message #63429 is a reply to message #63419] |
Mon, 04 October 2004 11:57 |
Frank Naude
Messages: 4587
Registered: April 1998
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Senior Member |
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Hi,
The following from http://asktom.oracle.com/pls/ask/f?p=4950:8:::::F4950_P8_DISPLAYID:365088445659:
"The fixed SGA is a component of the SGA that varies in size from platform to platform and release to release. It is "compiled" into the database. The fixed SGA contains a set of variables that point to the other components of the SGA and variables that contain the values of various parameters. The size of the fixed SGA is something over which we have no control and it is generally very small. Think of this area as a bootstrap" section of the SGA, something Oracle uses internally to find the other bits and pieces of the SGA."
Best regards.
Frank
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