session_cached_cursors参数

tom_fu

各位库友，我只知道这个参数可以用来指定能够缓存执行3次以上的SQL。如果指定数量是20的话，会有20个SQL被缓存。如果这时一直没有新的语句被缓存，是不是也会像数据缓冲区一样会定期对这部分内容进行清理？如果是清理的话，也是按照LRU的算法进行清理吗？
谢谢！

Maclean Liu(刘相兵

你可以做一个 errorstack dump ， 会转储出 Session Cached Cursors Dump

————– Generic Session Cached Cursors Dump ——–
———————————————————–
hash table=0x7f9baed440f0 cnt=4 LRU=0x7f9baed36ca0 cnt=4 hit=3 max=50 NumberOfTypes=6
type#0 name=DICTION count=0
type#1 name=BUNDLE count=0
type#2 name=SESSION count=4
type#3 name=PL/SQL count=0
type#4 name=CONSTRA count=0
type#5 name=REPLICA count=0
Bucket#051 seg=0x7f9baed44a78 nit=5 nal=5 ips=5 sz=56 flg=3 ucnt=1
0 cob=0x7f9baed54940 idx=33 flg=0 typ=2 cur=0x7f9baed58308 lru=1 fl=1
Bucket#098 seg=0x7f9baed45348 nit=5 nal=5 ips=5 sz=56 flg=3 ucnt=1
0 cob=0x7f9baed5c2b0 idx=62 flg=0 typ=2 cur=0x7f9baed5c3e0 lru=1 fl=1
Bucket#123 seg=0x7f9baed457f8 nit=5 nal=5 ips=5 sz=56 flg=3 ucnt=1
0 cob=0x7f9baed5be18 idx=7b flg=0 typ=2 cur=0x7f9baed5bf48 lru=1 fl=1
Bucket#203 seg=0x7f9baed466f8 nit=5 nal=5 ips=5 sz=56 flg=3 ucnt=1
0 cob=0x7f9baed5b980 idx=cb flg=0 typ=2 cur=0x7f9baed5bab0 lru=1 fl=1
———————————————————–
——Finished Dumping Generic Session Cached Cursors——
———————————————————–

tom_fu

从帖子上看我猜是会用LRU算法来决定回收，而且是直到缓存数目用尽或是内存紧张且没有设置CURSOR_SPACE_FOR_TIME时回收内存

anbob

The session cursor cache is a doubly linked list of cursor instantiation
objects. When a session attempts to close a cursor, if the parse count on the
corresponding shared cursor is 3 or more, then subject to the
session_cached_cursors parameter the instantiation object on the LRU end of the
cache may be deallocated, and the instantiation object for the cursor being
closed is cleaned up and added to the MRU end of the session cursor cache LRU
list.