Memory Structures - Expert Oracle Database Architecture - page 148

Within Oracle itself, you can see the SGA regardless of platform, using another magic V$ view called V$SGASTAT .
It might look as follows:
EODA@ORA12CR1> compute sum of bytes on pool
EODA@ORA12CR1> break on pool skip 1
EODA@ORA12CR1>
EODA@ORA12CR1> select pool, name, bytes
2 from v$sgastat
3 order by pool, name;
POOL NAME BYTES
------------ -------------------------- ----------
java pool free memory 4194304
************ ----------
sum 4194304
large pool PX msg pool 491520
free memory 3702784
************ ----------
sum 4194304
shared pool 1063.kgght 36784
11G QMN so 4144
177.kggfa 39840
...
zlllab Group Tree Heap De 160
************ ----------
sum 314572800
buffer_cache 184549376
fixed_sga 2290264
log_buffer 7938048
shared_io_pool 4194304
************ ----------
sum 198971992
1064 rows selected.
The SGA is broken up into various pools. Here are the major ones you'll see:
• Java pool : The Java pool is a fixed amount of memory allocated for the JVM running in the
database. In Oracle10 g and above, the Java pool may be resized online while the database is
up and running.
• Large pool : The large pool is used by shared server connections for session memory, by
parallel execution features for message buffers, and by RMAN backup for disk I/O buffers. This
pool is resizable online.
• Shared pool : The shared pool contains shared cursors, stored procedures, state objects,
dictionary caches, and many dozens of other bits of data. This pool is resizable online starting
from Oracle version 9i.