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DSGA [message #185431] Tue, 01 August 2006 13:52 Go to next message
Yasir Hashmi
Messages: 304
Registered: April 2006
Senior Member
Hey all,

How to size SGA dynamically without instance shutdown?

Thanks and Regards
Yasir Hashmi

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Re: DSGA [message #185440 is a reply to message #185431] Tue, 01 August 2006 14:33 Go to previous messageGo to next message
Yasir Hashmi
Messages: 304
Registered: April 2006
Senior Member
Silly of me iforgot the alter system set command

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Re: DSGA [message #185441 is a reply to message #185431] Tue, 01 August 2006 14:45 Go to previous messageGo to next message
alanm
Messages: 284
Registered: March 2005
Senior Member
how big is you max_sga_size and db_cach_size?

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Re: DSGA [message #185442 is a reply to message #185431] Tue, 01 August 2006 14:55 Go to previous messageGo to next message
Yasir Hashmi
Messages: 304
Registered: April 2006
Senior Member
SQL> startup
ORACLE instance started.

Total System Global Area 118561572 bytes
Fixed Size 453412 bytes
Variable Size 92274688 bytes
Database Buffers 25165824 bytes
Redo Buffers 667648 bytes
Database mounted.
Database opened.

DB_CACHE_SIZE 25165824 BYTES

What determines the size of database buffers?
Is it DB_CACHE_SIZE or DB_BLOCK_SIZE

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Re: DSGA [message #185445 is a reply to message #185431] Tue, 01 August 2006 15:42 Go to previous messageGo to next message
Yasir Hashmi
Messages: 304
Registered: April 2006
Senior Member
Redo log buffer size depends on LOG_BUFFER parameter.
Its size is 524288 bytes but in the startup command
SQL> startup
ORACLE instance started.

Total System Global Area 118561572 bytes
Fixed Size 453412 bytes
Variable Size 92274688 bytes
Database Buffers 25165824 bytes
Redo Buffers 667648 bytes
Database mounted.
Database opened.

it is 667648 bytes.
From where are the remaining bytes coming?

Thanks and Regards
Yasir Hashmi

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Re: DSGA [message #185450 is a reply to message #185431] Tue, 01 August 2006 16:29 Go to previous messageGo to next message
alanm
Messages: 284
Registered: March 2005
Senior Member
what version of database are you using, I guess 9i or 10g

db_cache_size defines (mainly) the sga size. Max_sga_size is the max size the sga can grow too by alter system set db_cache_size.

I guess also that you db_block_size is set to 8k

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Re: DSGA [message #185452 is a reply to message #185431] Tue, 01 August 2006 17:22 Go to previous message
Yasir Hashmi
Messages: 304
Registered: April 2006
Senior Member
DB_CACHE_SIZE determines the database buffer size.

LOG_BUFFER determines the Redo Buffer size.

LOG_BUFFER value is 524288 bytes but in the STARTUP command
Redo Buffers size is 667648 bytes.
Are there any additional parameters on which Redo Buffers size depend?

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