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Configuring the Reserved Pool
Database Performance Tuning Guide7.3.8 Configuring the Reserved PoolIf there is not enough free space in the shared pool, then Oracle Database must search for and free enough memory to satisfy this request. This operation could conceivably hold the latch resource for detectable peri...
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char, varchar2, nchar, nvarchar2
本文主要比较一下char、varchar2、nchar、nvarchar2的区别。1.字符集不同数据库在创建的时候会指定两个字符集，Character set 和 NCHAR Character set；char、varchar2用Character set存储；nchar、nvarchar2用NCHAR Character set存储select * from database_properties where property_name like '%...
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interval第一个分区限制
oracle 11g增加了range interval分区，可以根据间隔自行添加分区。省去了手动添加分区的操作。但是range interval的第一个分区不能删除，这样对数据淘汰需求会造成一些影响，所以这种情况第一个分区要多考滤一些。1.创建表create table tb_interval( c1 number)partition by range(c1) interval(1)...
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SYS_REFCURSOR & REF CURSOR
SYS_REFCURSOR 用来定义变量；REF CURSOR 用来定制数据类型。SYS_REFCURSOR 是一种弱类型的 REF CURSOR。declare type genericcurtyp is ref cursor; -- weak type cursor2 genericcurtyp; -- weak cursor variable my_cursor sys_re...
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CURSOR Expressions
CURSOR Expressions A CURSOR expression returns a nested cursor. This form of expression is equivalent to the PL/SQL REF CURSOR and can be passed as a REF CURSOR argument to a function.CRUSOR表达式返回一个嵌套的CUROS。这种格式的表达式相当于PL/SQL中的REF ...
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user_objects视图中created、last_ddl_time、timestamp字段含意
user_objects视图中created、last_ddl_time、timestamp字段含意created：对象的创建时间last_ddl_time：跟对象相关的（不一定是改变对象的结构，也可以是其他相关，如，如果此对象是表，则将该表的select权...
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HIDDENT_COLUMN、VIRTUAL_COLUMN
HIDDENT_COLUMN、VIRTUAL_COLUMNuser_tab_cols视图中有两个字段HIDDENT_COLUMN、VIRTUAL_COLUMN，分别表示 表中的字段是否隐藏、是否是虚拟字段。HIDDENT_COLUMN：YES是隐藏列，NO不是隐藏列。VIRTUAL_C...
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Providing for Secure Redo Data Transmission
Providing for Secure Redo Data TransmissionDG提供安全重做数据传输Data Guard provides a secure environment and prevents the possible tampering of redo data as it is being transferred to the sta...
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LRU算法与全表扫描
The LRU Algorithm and Full Table ScansLRU算法与全表扫描When the user process is performing a full table scan, it reads the blocks of the table into buffers and puts them on the LRU end (instea...
