TimesTen 应用层数据库缓存学习：7. 同步读写缓存

2024-02-04 13:48
文章标签 学习 数据库 读写 同步 缓存 应用层 timesten

本文主要是介绍TimesTen 应用层数据库缓存学习：7. 同步读写缓存，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

同步读写缓存(SWT)比较少用到，它性能肯定是不如AWT，但数据一致性强于AWT。
数据先在Oracle提交，然后才在TimesTen中提交，因此TimesTen的约束可以比Oracle弱。

和AWT一样，SWT的定义不能出现where条件
和AWT一样，虽然Oracle端可以修改，但是不建议。

定义dynamic SWT缓存

CREATE DYNAMIC SYNCHRONOUS WRITETHROUGH CACHE GROUP "D_SWT" FROM"TTHR"."DEPARTMENTS" ("DEPARTMENT_ID"   NUMBER(4)         NOT NULL,"DEPARTMENT_NAME" VARCHAR2(30 BYTE) NOT NULL,"MANAGER_ID"      NUMBER(6)        ,"LOCATION_ID"     NUMBER(4)        ,PRIMARY KEY("DEPARTMENT_ID"))AGING LRU ONcachaadm> cachegroups;Cache Group CACHEADM.D_SWT:Cache Group Type: Synchronous Writethrough (Dynamic)Autorefresh: NoAging: LRU onRoot Table: TTHR.DEPARTMENTSTable Type: Propagate1 cache group found.cacheadm> call ttrepstart;8191: This store (CACHEDB1_1122 on TIMESTEN-HOL) is not involved in a replication scheme
The command failed.

SWT缓存无需cache agent，因为其是在Oracle中先提交，所以AWT是复制，而SWT是两阶段提交。
上例中ttrepstart失败也说明了这一点。

tthr> select * from departments;
0 rows found.
tthr> select * from departments where department_id = 80;
< 80, Sales, 145, 2500 > <-dynamic load
1 row found.
Command> load cache group d_swt where department_id < 100 commit every 256 rows;
8 cache instances affected.
tthr>select * from departments;
< 10, Administration, 200, 1700 >
< 20, Marketing, 201, 1800 >
< 30, Purchasing, 114, 1700 >
< 40, Human Resources, 203, 2400 >
< 50, Shipping, 121, 1500 >
< 60, IT, 103, 1400 >
< 70, Public Relations, 204, 2700 >
< 80, Sales, 145, 2500 >
< 90, Executive, 100, 1700 >
9 rows found.
tthr>update departments set department_name = 'SALES' where department_id = 80;
1 row updated.
SQL> select * from departments where department_id = 80;DEPARTMENT_ID DEPARTMENT_NAME                MANAGER_ID LOCATION_ID
------------- ------------------------------ ---------- -----------80 SALES                                 145        2500

由于不建议在Oracle端修改数据，因此refresh操作通常意义不大，不过我们还是做了一个测试，来说明refresh的行为特征：

SQL> update departments set department_name = 'Sales' where department_id = 80;1 row updated.SQL> commit;Commit complete.
cacheadm>refresh cache group d_swt where department_id = 80 commit every 256 rows;3022: Refresh cache group with a where clause is only allowed only if the cache group is not dynamic
The command failed.
tthr>select * from departments where department_id = 80;
< 80, SALES, 145, 2500 >
1 row found.cacheadm>refresh cache group d_swt commit every 256 rows;
9 cache instances affected.
tthr>select * from departments where department_id = 80;
< 80, Sales, 145, 2500 >
1 row found.

错误处理

在Oralce中失败，在TimesTen中成功，这时需要在TimesTen端rollback交易

If the transaction fails to commit in the Oracle database, the application must roll back the transaction in TimesTen.

tthr>set autocommit off
tthr>call ttCachePropagateFlagSet(0); <- 设置timesten中的更改不传递到Oracle
tthr>delete from departments where department_id = 80;
1 row deleted.
tthr>commit;
tthr>select * from departments;
< 10, Administration, 200, 1700 >
< 20, Marketing, 201, 1800 >
< 30, Purchasing, 114, 1700 >
< 40, Human Resources, 203, 2400 >
< 50, Shipping, 121, 1500 >
< 60, IT, 103, 1400 >
< 70, Public Relations, 204, 2700 >
< 90, Executive, 100, 1700 >
8 rows found.
tthr>call ttCachePropagateFlagSet(1);
# TimesTen中数据已删，而Oracle数据仍在
SQL> select * from departments where department_id = 80;DEPARTMENT_ID DEPARTMENT_NAME                MANAGER_ID LOCATION_ID
------------- ------------------------------ ---------- -----------80 Sales                                 145        2500# TimesTen插入数据成功，但Oracle端重复索引故障
tthr>insert into departments values(80, 'Sales', 145, 2500);
1 row inserted.
tthr>commit;5210: Oracle unique constraint violation error in OCIStmtExecute(): ORA-00001: unique constraint (TTHR.SYS_C0014410) violated rc = -15055: Cannot synchronize Oracle with TimesTen.  The TimesTen transaction must be rolled back.5025: Commit failure in Oracle. Transaction must be rolled back in TimesTen.
The command failed.
tthr>select * from departments;5025: Commit failure in Oracle. Transaction must be rolled back in TimesTen.
The command failed.
tthr>rollback; <-TimesTen端(应用端)必须执行回退操作
tthr>select * from departments;
< 10, Administration, 200, 1700 >
< 20, Marketing, 201, 1800 >
< 30, Purchasing, 114, 1700 >
< 40, Human Resources, 203, 2400 >
< 50, Shipping, 121, 1500 >
< 60, IT, 103, 1400 >
< 70, Public Relations, 204, 2700 >
< 90, Executive, 100, 1700 >
8 rows found.
这时数据已经不一致了，我们仍可以用ttCachePropagateFlagSet来将数据补齐
tthr>autocommit 0
tthr>show autocommit
autocommit = 0 (OFF)
tthr>call ttCachePropagateFlagSet(0);
tthr>insert into departments values(80, 'Sales', 145, 2500);
1 row inserted.
tthr>commit;
tthr>call ttCachePropagateFlagSet(1);
tthr>select count(*) from departments;
< 9 >
1 row found.
tthr>passthrough 3
tthr>select count(*) from departments;
< 27 >
1 row found.
tthr>select count(*) from departments where department_id < 100;
< 9 >
1 row found.
tthr>passthrough 0

如果Oracle端成功，而TimesTen端失败，那么两边的数据就不一致了，需要人工同步

If the Oracle Database transaction commits successfully but the TimesTen transaction fails to commit, the cache tables in the SWT cache group are no longer synchronized with the cached Oracle Database tables.

cacheadm>unload cache group d_swt;
9 cache instances affected.
cacheadm>load cache group d_swt where department_id < 100 commit every 256 rows;
9 cache instances affected.
# 在TimesTen端插入一条数据，并且不同步到Oracle
tthr>autocommit;
autocommit = 1 (ON)
tthr>call ttCachePropagateFlagSet(0);
tthr>select * from departments;
< 10, Administration, 200, 1700 >
< 20, Marketing, 201, 1800 >
< 30, Purchasing, 114, 1700 >
< 40, Human Resources, 203, 2400 >
< 50, Shipping, 121, 1500 >
< 60, IT, 103, 1400 >
< 70, Public Relations, 204, 2700 >
< 80, Sales, 145, 2500 >
< 90, Executive, 100, 1700 >
9 rows found.
tthr>insert into departments values(99, 'Consultant', 145, 2500);
1 row inserted.
tthr>commit;
tthr>call ttCachePropagateFlagSet(1);
tthr>autocommit 1;
tthr>insert into departments values(99, 'Consultant', 145, 2500);907: Unique constraint (DEPARTMENTS on TTHR.DEPARTMENTS) violated at Rowid <BMUFVUAAABWAgAAFBd>
The command failed.
# Oracle端数据插入成功
SQL> select * from departments where department_id = 99;DEPARTMENT_ID DEPARTMENT_NAME                MANAGER_ID LOCATION_ID
------------- ------------------------------ ---------- -----------99 Consultant                            145        2500
# 由于TimesTen无法控制Oracle端，因此成功的交易也就无法回退了，这时数据不一致，需要人工补数据

Explicitly SWT的load和refresh

tthr>cachegroups;Cache Group CACHEADM.SWT:Cache Group Type: Synchronous WritethroughAutorefresh: NoAging: LRU onRoot Table: TTHR.DEPARTMENTSTable Type: Propagate1 cache group found.
tthr>select * from departments;
0 rows found.# 简单的说，对于explicitly缓存组，refresh就等于unload+load，开销很大。load等于insert。
cacheadm>load cache group swt where department_id < 100 commit every 256 rows;
10 cache instances affected.
cacheadm>load cache group swt where department_id < 100 commit every 256 rows;
0 cache instances affected.
cacheadm>refresh cache group swt where department_id < 100 commit every 256 rows;
10 cache instances affected.
cacheadm>refresh cache group swt where department_id < 100 commit every 256 rows;
10 cache instances affected.
cacheadm>refresh cache group swt where department_id < 100 commit every 256 rows;
10 cache instances affected.
cacheadm>refresh cache group swt  commit every 256 rows;
28 cache instances affected.
cacheadm>load cache group swt where department_id < 100 commit every 256 rows;
0 cache instances affected.

清理cache group

就说一点，无需停rep agent就行了，因为他用不到

这篇关于TimesTen 应用层数据库缓存学习：7. 同步读写缓存的文章就介绍到这儿，希望我们推荐的文章对编程师们有所帮助！


http://www.chinasem.cn/article/677708。

相关文章

Java实现本地缓存的四种方法实现与对比

Java实现本地缓存的四种方法实现与对比

《Java实现本地缓存的四种方法实现与对比》本地缓存的优点就是速度非常快,没有网络消耗,本地缓存比如caffine,guavacache这些都是比较常用的,下面我们来看看这四种缓存的具体实现吧... 目录1、HashMap2、Guava Cache3、Caffeine4、Encache本地缓存比如 caff
阅读更多...
MySQL 数据库表操作完全指南:创建、读取、更新与删除实战

MySQL 数据库表操作完全指南:创建、读取、更新与删除实战

《MySQL数据库表操作完全指南:创建、读取、更新与删除实战》本文系统讲解MySQL表的增删查改（CURD）操作,涵盖创建、更新、查询、删除及插入查询结果,也是贯穿各类项目开发全流程的基础数据交互原... 目录mysql系列前言一、Create(创建)并插入数据1.1 单行数据 + 全列插入1.2 多行数据
阅读更多...
MySQL 数据库表与查询操作实战案例

MySQL 数据库表与查询操作实战案例

《MySQL数据库表与查询操作实战案例》本文将通过实际案例,详细介绍MySQL中数据库表的设计、数据插入以及常用的查询操作,帮助初学者快速上手,感兴趣的朋友跟随小编一起看看吧... 目录mysql 数据库表操作与查询实战案例项目一：产品相关数据库设计与创建一、数据库及表结构设计二、数据库与表的创建项目二：员
阅读更多...
C#控制台程序同步调用WebApi实现方式

C#控制台程序同步调用WebApi实现方式

《C#控制台程序同步调用WebApi实现方式》控制台程序作为Job时,需同步调用WebApi以确保获取返回结果后执行后续操作,否则会引发TaskCanceledException异常,同步处理可避免异... 目录同步调用WebApi方法Cls001类里面的写法总结控制台程序一般当作Job使用，有时候需要控制
阅读更多...
Python学习笔记之getattr和hasattr用法示例详解

Python学习笔记之getattr和hasattr用法示例详解

《Python学习笔记之getattr和hasattr用法示例详解》在Python中,hasattr()、getattr()和setattr()是一组内置函数,用于对对象的属性进行操作和查询,这篇文章... 目录1.getattr用法详解1.1 基本作用1.2 示例1.3 原理2.hasattr用法详解2.
阅读更多...
Android 缓存日志Logcat导出与分析最佳实践

Android 缓存日志Logcat导出与分析最佳实践

《Android缓存日志Logcat导出与分析最佳实践》本文全面介绍AndroidLogcat缓存日志的导出与分析方法,涵盖按进程、缓冲区类型及日志级别过滤,自动化工具使用,常见问题解决方案和最佳实... 目录android 缓存日志（Logcat）导出与分析全攻略为什么要导出缓存日志？按需过滤导出1. 按
阅读更多...
MybatisPlus中removeById删除数据库未变解决方案

MybatisPlus中removeById删除数据库未变解决方案

《MybatisPlus中removeById删除数据库未变解决方案》MyBatisPlus中,removeById需实体类标注@TableId注解以识别数据库主键,若字段名不一致,应通过value属... 目录MyBATisPlus中removeBypythonId删除数据库未变removeById(Se
阅读更多...
在 Spring Boot 中连接 MySQL 数据库的详细步骤

在 Spring Boot 中连接 MySQL 数据库的详细步骤

《在SpringBoot中连接MySQL数据库的详细步骤》本文介绍了SpringBoot连接MySQL数据库的流程,添加依赖、配置连接信息、创建实体类与仓库接口,通过自动配置实现数据库操作,... 目录一、添加依赖二、配置数据库连接三、创建实体类四、创建仓库接口五、创建服务类六、创建控制器七、运行应用程序八
阅读更多...
MySQL中读写分离方案对比分析与选型建议

MySQL中读写分离方案对比分析与选型建议

《MySQL中读写分离方案对比分析与选型建议》MySQL读写分离是提升数据库可用性和性能的常见手段,本文将围绕现实生产环境中常见的几种读写分离模式进行系统对比,希望对大家有所帮助... 目录一、问题背景介绍二、多种解决方案对比2.1 原生mysql主从复制2.2 Proxy层中间件：ProxySQL2.3
阅读更多...
Linux线程同步/互斥过程详解

Linux线程同步/互斥过程详解

《Linux线程同步/互斥过程详解》文章讲解多线程并发访问导致竞态条件,需通过互斥锁、原子操作和条件变量实现线程安全与同步,分析死锁条件及避免方法,并介绍RAII封装技术提升资源管理效率... 目录01. 资源共享问题1.1 多线程并发访问1.2 临界区与临界资源1.3 锁的引入02. 多线程案例2.1 为
阅读更多...

Copyright China编程 23002807@qq.com

沪ICP备2023033072号-2