对oracle实例的内存（SGA和PGA）进行调整，优化数据库性(34)

来源：未知责任编辑：责任编辑发表时间:2013-11-26 22:16　点击:次

+sum(reloads)))*100) "relhitratio"
from V$librarycache

PINS NUMBER Number of times a PIN was requested for objects of this namespace
PINHITS NUMBER Number of times all of the metadata pieces of the library object were found in memory
RELOADS NUMBER Any PIN of an object that is not the first PIN performed since the object handle was created, and which requires loading the object from disk

Oracle把从data buffer中获得的数据库叫cache hit，把从磁盘获得的脚cache miss
数据缓冲区中的数据块通过脏列表（dirty list）和LRU列表（LRU list）来管理。