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

PostgreSQ数据库实现在Windows上异地自动备份指南的详细教程

PostgreSQ数据库实现在Windows上异地自动备份指南的详细教程

《PostgreSQ数据库实现在Windows上异地自动备份指南的详细教程》这篇文章主要为大家详细介绍了如何在Windows系统上实现PostgreSQL数据库的异地自动备份,文中的示例代码讲解详细,... 目录前期准备实现步骤步骤一：创建备份脚本步骤二：配置免密登录（可选但推荐）步骤三：设置任务计划程序步
阅读更多...
JavaWeb项目创建、部署、连接数据库保姆级教程(tomcat)

JavaWeb项目创建、部署、连接数据库保姆级教程(tomcat)

《JavaWeb项目创建、部署、连接数据库保姆级教程(tomcat)》：本文主要介绍如何在IntelliJIDEA2020.1中创建和部署一个JavaWeb项目,包括创建项目、配置Tomcat服务... 目录简介：一、创建项目二、tomcat部署1、将tomcat解压在一个自己找得到路径2、在idea中添加
阅读更多...
MySQL MHA集群详解(数据库高可用)

MySQL MHA集群详解(数据库高可用)

《MySQLMHA集群详解(数据库高可用)》MHA（MasterHighAvailability）是开源MySQL高可用管理工具,用于自动故障检测与转移,支持异步或半同步复制的MySQL主从架构,本... 目录mysql 高可用方案：MHA 详解与实战1. MHA 简介2. MHA 的组件组成（1）MHA
阅读更多...
MySQL 数据库进阶之SQL 数据操作与子查询操作大全

MySQL 数据库进阶之SQL 数据操作与子查询操作大全

《MySQL数据库进阶之SQL数据操作与子查询操作大全》本文详细介绍了SQL中的子查询、数据添加（INSERT）、数据修改（UPDATE）和数据删除（DELETE、TRUNCATE、DROP）操作... 目录一、子查询：嵌套在查询中的查询1.1 子查询的基本语法1.2 子查询的实战示例二、数据添加：INSE
阅读更多...
在SpringBoot+MyBatis项目中实现MySQL读写分离的实战指南

在SpringBoot+MyBatis项目中实现MySQL读写分离的实战指南

《在SpringBoot+MyBatis项目中实现MySQL读写分离的实战指南》在SpringBoot和MyBatis项目中实现MySQL读写分离,主要有两种思路：一种是在应用层通过代码和配置手动控制... 目录如何选择实现方案核心实现：应用层手动分离实施中的关键问题与解决方案总结在Spring Boot和
阅读更多...
通过DBeaver连接GaussDB数据库的实战案例

通过DBeaver连接GaussDB数据库的实战案例

《通过DBeaver连接GaussDB数据库的实战案例》DBeaver是一个通用的数据库客户端,可以通过配置不同驱动连接各种不同的数据库,：本文主要介绍通过DBeaver连接GaussDB数据库的... 目录​一、前置条件​二、连接步骤​三、常见问题与解决方案​1. 驱动未找到​2. 连接超时​3. 权限不
阅读更多...
MySQL数据库读写分离与负载均衡的实现逻辑

MySQL数据库读写分离与负载均衡的实现逻辑

《MySQL数据库读写分离与负载均衡的实现逻辑》读写分离与负载均衡是数据库优化的关键策略,读写分离的核心是将数据库的读操作与写操作分离,本文给大家介绍MySQL数据库读写分离与负载均衡的实现方式,感兴... 目录读写分离与负载均衡的核心概念与目的读写分离的必要性与实现逻辑读写分离的实现方式及优缺点读负载均衡
阅读更多...
Go语言中如何进行数据库查询操作

Go语言中如何进行数据库查询操作

《Go语言中如何进行数据库查询操作》在Go语言中,与数据库交互通常通过使用数据库驱动来实现,Go语言支持多种数据库,如MySQL、PostgreSQL、SQLite等,每种数据库都有其对应的官方或第三... 查询函数QueryRow和Query详细对比特性QueryRowQuery返回值数量1个：*sql
阅读更多...
Mysql数据库聚簇索引与非聚簇索引举例详解

Mysql数据库聚簇索引与非聚簇索引举例详解

《Mysql数据库聚簇索引与非聚簇索引举例详解》在MySQL中聚簇索引和非聚簇索引是两种常见的索引结构,它们的主要区别在于数据的存储方式和索引的组织方式,：本文主要介绍Mysql数据库聚簇索引与非... 目录前言一、核心概念与本质区别二、聚簇索引（Clustered Index）1. 实现原理（以 Inno
阅读更多...
MySQL数据库双机热备的配置方法详解

MySQL数据库双机热备的配置方法详解

《MySQL数据库双机热备的配置方法详解》在企业级应用中,数据库的高可用性和数据的安全性是至关重要的,MySQL作为最流行的开源关系型数据库管理系统之一,提供了多种方式来实现高可用性,其中双机热备（M... 目录1. 环境准备1.1 安装mysql1.2 配置MySQL1.2.1 主服务器配置1.2.2 从
阅读更多...

Copyright China编程 23002807@qq.com

沪ICP备2023033072号-2