Oracle 10 Gb SGA size at startup, oracle10gsga size

Oracle 10 Gb SGA size at startup, oracle10gsga size

The size of the SGA started in Oracle 10g Database is determined by sga_target and sga_max_size. The following three cases are discussed:

Sga_target = sga_max_size

Parameter file value

*.sga_target=599785472

Start

SQL> startupORACLE instance started.Total System Global Area  599785472 bytesFixed Size          2022632 bytesVariable Size         171967256 bytesDatabase Buffers      423624704 bytesRedo Buffers            2170880 bytesDatabase mounted.Database opened.

Sga_target <sga_max_size
Parameter file value

*.sga_max_size=800m*.sga_target=700m

Start Database

SQL> startupORACLE instance started.Total System Global Area  838860800 bytesFixed Size          2024496 bytesVariable Size         297798608 bytesDatabase Buffers      536870912 bytesRedo Buffers            2166784 bytesDatabase mounted.Database opened.

SQL> select 838860800/1024/1024 from dual;838860800/1024/1024-------------------        800SQL> show parameter sga_NAME                   TYPE      VALUE------------------- ----------- -----------------------sga_max_size         big integer 800Msga_target           big integer 700M

Sga_target> sga_max_size

Parameter file value

*.sga_max_size=600m*.sga_target=700m

The actual startup size of the database

SQL> startupORACLE instance started.Total System Global Area  734003200 bytesFixed Size          2023656 bytesVariable Size         192941848 bytesDatabase Buffers      536870912 bytesRedo Buffers            2166784 bytesDatabase mounted.Database opened.

SQL> select 734003200/1024/1024 from dual;734003200/1024/1024-------------------        700SQL> show parameter sga_   NAME                     TYPE    VALUE------------------------------------ ----------- ------------------------------sga_max_size                 big integer 700Msga_target               big integer 700M

Experiment conclusion
From the above three experiments, we can see that the size of the SGA during database startup is determined by the greater limit in SGA_TARGET and SGA_MAX_SIZE.

When SGA_TARGET <= SGA_MAX_SIZE, SGA_MAX_SIZE prevails.
When SGA_TARGET> SGA_MAX_SIZE, assign the value of SGA_TARGET to SGA_MAX_SIZE, and then use SGA_MAX_SIZE as the standard.