Expand SGA but performance slow down?

Expand SGA but performance slow down?

Post by Viol » Thu, 20 Aug 1998 04:00:00



Hello,
2 days ago I changed  the init.ora and startup again.
In init.ora,I changed the:
db_block_buffers =  200           -->  6400  
shared_pool_size = 3500000 --> 10000000
log_buffer = 8192  --> 245760
processes =  50    -->100

After startup database again,the SGA allocated successfully.
Database Buffers = 400K  -->  12800KBytes
Fixed Size=35K  --> 31K
Redo Buffers=8K --> 240K
Variable Size=6887K --> 12526K

When I do the same SQL for a large amount of rows(about 37,000) for
select and insert statement,
Before changed SGA,the statement takes 5 seconds to complete.
After changed SGA,it takes 17 seconds to complete.
Why???
Isn't the SGA more large more better?
If you know why,please tell me.

 
 
 

Expand SGA but performance slow down?

Post by Moto » Thu, 20 Aug 1998 04:00:00


Not if the SGA is getting swapped, it isn't. Have you monitored the swap
activity before and after to see what is happening? You really need to
monitor *both* the OS and Oracle when you make changes of this type. Get
yourself some good performance monitoring tools for both (or roll your own)
if you don't already have them.

MotoX.


>Hello,
>2 days ago I changed  the init.ora and startup again.
>In init.ora,I changed the:
>db_block_buffers =  200           -->  6400
>shared_pool_size = 3500000 --> 10000000
>log_buffer = 8192  --> 245760
>processes =  50    -->100

>After startup database again,the SGA allocated successfully.
>Database Buffers = 400K  -->  12800KBytes
>Fixed Size=35K  --> 31K
>Redo Buffers=8K --> 240K
>Variable Size=6887K --> 12526K

>When I do the same SQL for a large amount of rows(about 37,000) for
>select and insert statement,
>Before changed SGA,the statement takes 5 seconds to complete.
>After changed SGA,it takes 17 seconds to complete.
>Why???
>Isn't the SGA more large more better?
>If you know why,please tell me.



 
 
 

1. Expand SGA but performance slow down?

Hello,
2 days ago I changed  the init.ora and startup again.
In init.ora,I changed the:
db_block_buffers =  200           -->  6400  
shared_pool_size = 3500000 --> 10000000
log_buffer = 8192  --> 245760
processes =  50    -->100

After startup database again,the SGA allocated successfully.
Database Buffers = 400K  -->  12800KBytes
Fixed Size=35K  --> 31K
Redo Buffers=8K --> 240K
Variable Size=6887K --> 12526K

When I do the same SQL for a large amount of rows(about 37,000) for
select and insert statement,
Before changed SGA,the statement takes 5 seconds to complete.
After changed SGA,it takes 17 seconds to complete.
Why???
Isn't the SGA more large more better?
If you know why,please tell me.

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