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1. 测试环境
OS: RHEL5U5(32bit)
DB: Oracle 11.2.0.3.0(32bit)
2. 异常原因.
2.1 oracle 11g默认sga_target为0，如下图, Oracle 10g开始,引入SGA_TARGET初始化参数, 让oracle自动管理SGA中(Buffer cache (DB_CACHE_SIZE),Shared pool (SHARED_POOL_SIZE),Large pool (LARGE_POOL_SIZE),Java pool (JAVA_POOL_SIZE),Streams pool (STREAMS_POOL_SIZE))的内存自动分配，即ASSM(Automatic Shared Memory Management). 如下为引自oracle官方文档解释.如下.
SYS> show parameter sga;
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
lock_sga boolean FALSE
pre_page_sga boolean FALSE
sga_max_size big integer 632M
sga_target big integer 0
SYS>
| Property | Description |
|---|---|
| Parameter type | Big integer |
| Syntax | SGA_TARGET = integer [K | M | G] |
| Default value | 0 (SGA autotuning is disabled for DEFERRED mode autotuning requests, but allowed for IMMEDIATE mode autotuning requests) |
| Modifiable | ALTER SYSTEM |
| Range of values | 64 MB to operating system-dependent |
| Basic | Yes |
SGA_TARGET specifies the total size of all SGA components. If SGA_TARGET is specified, then the following memory pools are automatically sized:
Buffer cache (DB_CACHE_SIZE)
Shared pool (SHARED_POOL_SIZE)
Large pool (LARGE_POOL_SIZE)
Java pool (JAVA_POOL_SIZE)
Streams pool (STREAMS_POOL_SIZE)
If these automatically tuned memory pools are set to nonzero values, then those values are used as minimum levels by Automatic Shared Memory Management. You would set minimum values if an application component needs a minimum amount of memory to function properly.
The following pools are manually sized components and are not affected by Automatic Shared Memory Management:
Log buffer
Other buffer caches, such as KEEP, RECYCLE, and other block sizes
Fixed SGA and other internal allocations
| Property | Description |
|---|---|
| Parameter type | Big integer |
| Syntax | PGA_AGGREGATE_TARGET = integer [K | M | G] |
| Default value | 10 MB or 20% of the size of the SGA, whichever is greater |
| Modifiable | ALTER SYSTEM |
| Range of values | Minimum: 10 MB
Maximum: 4096 GB - 1 |
| Basic | Yes |
PGA_AGGREGATE_TARGET specifies the target aggregate PGA memory available to all server processes attached to the instance.
ORA-00838: Specified value of MEMORY_TARGET is too small(转)
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原文地址：http://www.cnblogs.com/softidea/p/4819696.html
