oracle内存管理

查看当前分配的大小:
SQL> select component,current_size from v$sga_dynamic_components where component='KEEP buffer cache';
COMPONENT CURRENT_SIZE
---------------------------------------------------------------- ------------
KEEP buffer cache 54525952
SQL> select name,current_size from v$buffer_pool;
NAME CURRENT_SIZE
-------------------- ------------
KEEP 52
DEFAULT 84
修改当前keep分配的大小
SQL> alter system set db_keep_cache_size=30M scope=both;
再查询:
SQL> select component,current_size from v$sga_dynamic_components where component='KEEP buffer cache';
SQL> select name,current_size from v$buffer_pool;
.................................................
recycle pool:
SQL> select component,current_size from v$sga_dynamic_components where component='RECYCLE buffer cache';
COMPONENT CURRENT_SIZE
---------------------------------------------------------------- ------------
RECYCLE buffer cache 0
SQL> select name,current_size from v$buffer_pool;
NAME CURRENT_SIZE
-------------------- ------------
KEEP 56
DEFAULT 80
SQL> alter system set db_recycle_cache_size=10M scope=both;
alter system db_recycle_cache_size=10M scope=both
SQL> select name,current_size from v$buffer_pool;
NAME CURRENT_SIZE
-------------------- ------------
KEEP 56
RECYCLE 12
DEFAULT 68
........................
shared_pool:
查看 shared _pool 参数默认值
SQL> show parameter shared_pool_size;
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
shared_pool_size big integer 0
查看当前运行期间分配给shared_pool的大小
SQL> select pool,sum(bytes) from v$sgastat group by pool;
POOL SUM(BYTES)
------------ ----------
142606188
java pool 4194304
shared pool 58724948
large pool 4194304
Library cache:(SQL语句缓冲)
SQL> select sum(sharable_mem) from v$db_object_cache;
SUM(SHARABLE_MEM)
-----------------
7416202
实例引证:
SQL> set timing on
SQL> alter system flush shared_pool;
Elapsed: 00:00:00.13
SQL> select count(*) from dba_objects;
COUNT(*)
----------
50332
Elapsed: 00:00:00.19
查看保存在library cache中保存的已分析的SQL语句:
SQL> select * from v$sqltext where sql_text like '%dba_object%';
ADDRESS HASH_VALUE SQL_ID COMMAND_TYPE PIECE
-------- ---------- ------------- ------------ ----------
SQL_TEXT
----------------------------------------------------------------
3F952FD0 2935929963 g4pkmrqrgxg3b 3 0
select count(*) from dba_objects
3FA3D868 2816052306 024c6akmxm32k 3 0
select * from v$sqltext where sql_text like '%dba_object%'
Elapsed: 00:00:00.09
SQL> c/*/sql_text
1* select sql_text from v$sqltext where sql_text like '%dba_object%'
SQL> /
SQL_TEXT
----------------------------------------------------------------
select count(*) from dba_objects
select * from v$sqltext where sql_text like '%dba_object%'
select sql_text from v$sqltext where sql_text like '%dba_object%
Elapsed: 00:00:00.06
Data Dictionary cache(数据字典缓冲):
SQL> select sum(sharable_mem) from v$sqlarea;
SUM(SHARABLE_MEM)
-----------------
3620010
Elapsed: 00:00:00.03
select * from dict;查看数据字典
select object_name,object_type,created from dba_objects where object_name in ('SC','PROC1');
select username from dba_users;
测试Data dictionary cache的作用
set autot on stat
select count(*) from dba_source; 查看recursive calls次数
select count(*) from dba_source; 再查recursive calls次数
数据字典中表的分类:
SQL> select count(*) from dict where table_name like'DBA%';
dba_*:当前数据库中所有数据库对象的描述.
COUNT(*)
----------
515
SQL> select count(*) from dict where table_name like'ALL%';
all_*当前用户能够访问的DB对象的描述
COUNT(*)
----------
272
SQL> select count(*) from dict where table_name like'USER%';
user_*当前用户所拥有的DB对象的描述
COUNT(*)
----------
285