Re: About SGA size

jeff wrote:

> I know that SGA contains three parts,Redo log buffer,database buffer ca
 che
> and shared pool.
> So I think the size of the SGA should be the sum of the three parts.
> I set the corresponding parameters like this:
>
 

> db block buffers integer 2048
> db block size integer 8192
> log buffer integer 163840
> shared pool size string 15728640
>
 

> I think the size of SGA should be:
>
 

> db block buffers(2048)*db block size(8192)+log buffer(163840)+shared po
 ol si
> ze(15728640)
> 777216 + 163840 +15728640
> 2,666,696
>
 

> But the result of command SHOW SGA in svrmgrl is:
> SVRMGR> show sga
> Total System Global Area 35605336 bytes
> Fixed Size 72536 bytes
> Variable Size 18583552 bytes
> Database Buffers 16777216 bytes
> Redo Buffers 172032 bytes
> SVRMGR>
>
 

> Who can help me to explain the difference.Thanks a lot.

It seems that Oracle adjusts the value of shared pool size set by the user using some unknown criteria.
I have:
db block buffers(12800)*db block size(2048)+log buffer(163840)+shared poo l size(36000000)
and my SGA is:

Total System Global Area      66090460 bytes
Fixed Size                       41880 bytes
Variable Size                 39670340 bytes (adjusted)
Database Buffers              26214400 bytes (OK)
Redo Buffers                    163840 bytes (OK)

Best regards, Cristian

-- 

Cristian Veronesi ><(((( > http://www.crpa.it

General rule for life: avoid pain for as long as possible
unless doing so will ultimately cause more pain.