专家解析：Oracle内存区域SGA与PGA
本文深入探讨了Oracle中共享全局区（SGA）与进程全局区（PGA）的概念，包括它们的区别、组件及其在不同服务器配置下的应用。重点分析了Redo缓冲区、块缓冲区缓存、共享池等关键组件的功能，并提供了查看SGA各部分大小的SQL查询示例。
notes on 'expert oracle'-no.4: memory areas-chenjianjx的专栏-iteye技术网站
2011年09月01日
1.SGA & PGA
a. SGA: Shared Area for all the processes/threads
b. PGA: The area for a single process/thread
SGA ∩ PGA ==
2.UGA: The area for the user
a. UGA SGA if "Shared Server" is used.
b. UGA PGA if "Dedicated Server" is used.
3.Important components of SGA
a.Redo Buffer -- extremely helpful for big/long transactions, since the redo log is involved for transactions.
b.Block Buffer Cache -- Caching query results
c.Shared Pool --
i. Bascially for compiled SQLs. So, always use "Bind variables" in SQLs because this way there will be too much SQLs in this pool(Think otherwise).
ii.LRU-Cache
d.Large Pool -- For large memory alloacation
4.SQLs for SGA
a. See pools
select * from V$SGASTAT
b. See pool size
select sum(bytes)/1024/1024 mbytes from V$SGASTAT where pool = 'shared pool'
2011年09月01日
1.SGA & PGA
a. SGA: Shared Area for all the processes/threads
b. PGA: The area for a single process/thread
SGA ∩ PGA ==
2.UGA: The area for the user
a. UGA SGA if "Shared Server" is used.
b. UGA PGA if "Dedicated Server" is used.
3.Important components of SGA
a.Redo Buffer -- extremely helpful for big/long transactions, since the redo log is involved for transactions.
b.Block Buffer Cache -- Caching query results
c.Shared Pool --
i. Bascially for compiled SQLs. So, always use "Bind variables" in SQLs because this way there will be too much SQLs in this pool(Think otherwise).
ii.LRU-Cache
d.Large Pool -- For large memory alloacation
4.SQLs for SGA
a. See pools
select * from V$SGASTAT
b. See pool size
select sum(bytes)/1024/1024 mbytes from V$SGASTAT where pool = 'shared pool'
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