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TimesTen 應(yīng)用層數(shù)據(jù)庫緩存學(xué)習(xí)：16. Aging策略與AWT緩存組

來源：程序員人生發(fā)布時(shí)間：2016-06-07 08:16:04 閱讀次數(shù)：3294次

本文討論如果1個(gè)Cache Table設(shè)定了Aging策略，那末Aging致使的緩存中數(shù)據(jù)的刪除是不是會影響到Oracle 數(shù)據(jù)庫?

如果是只讀緩存組，固然是不會影響到Oracle的。如果是AWT緩存組，答案也是不會影響，即Aging致使的數(shù)據(jù)刪除不會傳播到Oracle，下面通過實(shí)驗(yàn)驗(yàn)證1下。

之前的建立緩存組的準(zhǔn)備工作此處略過。

在Oracle中建立源表(schema 用戶 - tthr)：

create table t1(id int not null, t timestamp not null, primary key(id));

啟動cache agent。

建立AWT緩存組(cache管理用戶 - cacheadm)，定義Aging策略為基于TimeStamp，生命周期為10秒，檢查周期為5秒

CREATE DYNAMIC ASYNCHRONOUS WRITETHROUGH CACHE GROUP "AGEAWT" 
 FROM
  "TTHR"."T1" (
    "ID" NUMBER(38)   NOT NULL,
    "T"  TIMESTAMP(6) NOT NULL,
    PRIMARY KEY("ID")
  )
  AGING USE T LIFETIME 10 seconds CYCLE 5 seconds ON

  start rep agent

在TimesTen中插入數(shù)據(jù)

$ ttisql "dsn=cachedb1_1122;uid=tthr;pwd=timesten"

Copyright (c) 1996, 2014, Oracle and/or its affiliates. All rights reserved.
Type ? or "help" for help, type "exit" to quit ttIsql.



connect "dsn=cachedb1_1122;uid=tthr;pwd=timesten";
Connection successful: DSN=cachedb1_1122;UID=tthr;DataStore=/home/oracle/TimesTen/tt1122/info/DemoDataStore/cachedb1_1122;DatabaseCharacterSet=AL32UTF8;ConnectionCharacterSet=US7ASCII;DRIVER=/home/oracle/TimesTen/tt1122/lib/libtten.so;PermSize=40;TempSize=32;TypeMode=0;OracleNetServiceName=ttorcl;
(Default setting AutoCommit=1)
Command> select * from t1;
0 rows found.
Command> insert into t1 values(1, sysdate);
1 row inserted.
Command> select * from t1;
< 1, 2016-05-30 01:12:49.000000 >
1 row found.
Command> select * from t1; <- aging生效了
0 rows found.
Command> insert into t1 values(2, sysdate);
1 row inserted.
Command> select * from t1;
< 2, 2016-05-30 01:13:50.000000 >
1 row found.
Command> select * from t1; <- aging生效了
0 rows found.
Command>

在Oracle中視察數(shù)據(jù)變化, 可以看到數(shù)據(jù)不斷增加，沒有由于Aging而被刪除

$ sqlplus tthr/oracle@ttorcl

SQL*Plus: Release 11.2.0.2.0 Production on Mon May 30 01:12:27 2016

Copyright (c) 1982, 2010, Oracle.  All rights reserved.


Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> select * from t1;

no rows selected

SQL> select * from t1;

no rows selected

SQL> /

        ID
----------
T
---------------------------------------------------------------------------
         1
30-MAY⑴6 01.12.49.000000 AM


SQL> /

        ID
----------
T
---------------------------------------------------------------------------
         1
30-MAY⑴6 01.12.49.000000 AM

         2
30-MAY⑴6 01.13.50.000000 AM

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TimesTen 應(yīng)用層數(shù)據(jù)庫緩存學(xué)習(xí)：16. Aging策略與AWT緩存組