Chapter 1
oracle architecture compenents
SGA 的组成:五个重要的部分
shared pool
database buffer cache
redo log buffer
java pool
large pool
10g,11g 中有 stream pool
oracle server : is a database management system that provides an open comprehensive,integrated
approach to information management
包括 实例 和 数据库
oracle instance: 由内存 和 后台进程组成
Connection & Session
background processes
server process
oracle database:
一堆文件
Memory Structure:
SGA
PGA
ipcs
[root@wangjia ora10g]# ipcs
------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0x00000000 65536 oracle 660 536870912 32
0x16e430c4 98305 oracle 660 2097152 32
0x00000000 163842 gdm 600 393216 2 dest
------ Semaphore Arrays --------
key semid owner perms nsems
0xaf9b9dfc 98304 oracle 660 154
------ Message Queues --------
key msqid owner perms used-bytes messages
SGA:
是动态的,基本单位是granules,是SGA分配内存的基本单位
show sga;
show parameter sga_max_size;
show parameter sga_target;
SQL> select component,granule_size from v$sga_dynamic_components;
COMPONENT GRANULE_SIZE
---------------------------------------------------------------- ------------
shared pool 4194304
large pool 4194304
java pool 4194304
streams pool 4194304
DEFAULT buffer cache 4194304
KEEP buffer cache 4194304
RECYCLE buffer cache 4194304
DEFAULT 2K buffer cache 4194304
DEFAULT 4K buffer cache 4194304
DEFAULT 8K buffer cache 4194304
DEFAULT 16K buffer cache 4194304
COMPONENT GRANULE_SIZE
---------------------------------------------------------------- ------------
DEFAULT 32K buffer cache 4194304
ASM Buffer Cache 4194304
db_cache_size
log_buffer
shared_pool_size
large_pool_size
java_pool_size
10g,11g之后有了自动化的SGA管理,简化DBA对SGA的管理工作
Shared Pool:
SQL statements
recently used data definitions
consists:
library cache
data dictionary cache
alter system set shared_pool_size = 64m;
library cache:
SQL and PL/SQL statements
LRU
consists:
shared sql area
shared pl/sql area
size determined by the shared pool size;
data dictionary cache:
Data Buffer Cache:
cache hit
cache miss
db_block_size
存取数据块
db_cache_size
db_keep_cache_size
db_recycle_cache_size
db_cache_advice
v$db_cache_advice
Redo Log Buffer:
log_buffer
Large Pool:
I/O
RMAN
Java Pool:
java_pool_size
PGA:
Process Structure:
User process
Server process
Backgroud process
DBW0-DBW9
DBWa-DBWj
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