PostgreSQ的复制、高可用、负载均衡相关集群,这儿写个概要备查。PostgreSQ有以下各种基于复制的集群方案,多数配过,有的当时没
PostgreSQ的复制、高可用、负载均衡相关集群,这儿写个概要备查。
PostgreSQ有以下各种基于复制的集群方案,多数配过,,有的当时没有整理。现在网上也有很多这些集群配置的文档,在这篇文档后找完备点的集中一下备档,不用每次用时到处查。
基于流复制的功能内置、触发器主从复制slony,基于sql复制的PostgreSQpool-II,其它如同步多主复制EDB MMR(这个也支持异步复制,玩过的时间有点长了,后面要找到当年记录再总结),异步多主复制Bucardo,文件系统级别复制DRDB,共享磁盘失败切换NAS以后看情况补。
slony-i主从复制:主服务器异步发送数据改变到备服务器。基于触发器,表行级复制;主服务器可能overhead;不用等其它服务器可以结束事务;只有异步复制,可能丢失数据;备服务器支持只读查询;表级粒度;无冲突;需要开发人员维护写入都请求master,读请求都走slave机器???
现在有了内置的流复制功能,以后应该鲜有用slony的了吧!
PostgreSQpool-II:复制sql语句;支持多主;无主服务器overhead;所有服务器完成方可结束事务;不会丢失数据;从服务器支持只读查询;库级别复制???;需要冲突解决机制
流复制
复制wal日志;无主服务器overhead;异步复制不用等其它服务器可以结束事务;同步复制不会丢失数据;从服务器支持只读查询;实例级粒度;无冲突
另外,plproxy是skype开发的一个数据库组件。虽然plproxy只能做水平分片,把它也放到这儿。plproxy是skype开发的数据库组件。在使用过程中,需要考虑带宽和本地缓存等问题。它限制代理库数是2的次方。proxy在自定义的函数上实现转发功能。这要求实际应用中 需要把大量的业务逻辑放到PostgreSQL服务器端来完成,降低了灵活度。也给以后可能的数据库迁移带来了挑战。
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CentOS 6.3环境下yum安装PostgreSQL 9.3
PostgreSQL缓存详述
Windows平台编译 PostgreSQL
Ubuntu下LAPP(Linux+Apache+PostgreSQL+PHP)环境的配置与安装
Ubuntu上的phppgAdmin安装及配置
CentOS平台下安装PostgreSQL9.3
PostgreSQL配置Streaming Replication集群
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PostgreSQL 的详细介绍:请点这里
PostgreSQL 的下载地址:请点这里
本文永久更新链接地址:

MySQL is an open source relational database management system, mainly used to store and retrieve data quickly and reliably. Its working principle includes client requests, query resolution, execution of queries and return results. Examples of usage include creating tables, inserting and querying data, and advanced features such as JOIN operations. Common errors involve SQL syntax, data types, and permissions, and optimization suggestions include the use of indexes, optimized queries, and partitioning of tables.

MySQL is an open source relational database management system suitable for data storage, management, query and security. 1. It supports a variety of operating systems and is widely used in Web applications and other fields. 2. Through the client-server architecture and different storage engines, MySQL processes data efficiently. 3. Basic usage includes creating databases and tables, inserting, querying and updating data. 4. Advanced usage involves complex queries and stored procedures. 5. Common errors can be debugged through the EXPLAIN statement. 6. Performance optimization includes the rational use of indexes and optimized query statements.

MySQL is chosen for its performance, reliability, ease of use, and community support. 1.MySQL provides efficient data storage and retrieval functions, supporting multiple data types and advanced query operations. 2. Adopt client-server architecture and multiple storage engines to support transaction and query optimization. 3. Easy to use, supports a variety of operating systems and programming languages. 4. Have strong community support and provide rich resources and solutions.

InnoDB's lock mechanisms include shared locks, exclusive locks, intention locks, record locks, gap locks and next key locks. 1. Shared lock allows transactions to read data without preventing other transactions from reading. 2. Exclusive lock prevents other transactions from reading and modifying data. 3. Intention lock optimizes lock efficiency. 4. Record lock lock index record. 5. Gap lock locks index recording gap. 6. The next key lock is a combination of record lock and gap lock to ensure data consistency.

The main reasons for poor MySQL query performance include not using indexes, wrong execution plan selection by the query optimizer, unreasonable table design, excessive data volume and lock competition. 1. No index causes slow querying, and adding indexes can significantly improve performance. 2. Use the EXPLAIN command to analyze the query plan and find out the optimizer error. 3. Reconstructing the table structure and optimizing JOIN conditions can improve table design problems. 4. When the data volume is large, partitioning and table division strategies are adopted. 5. In a high concurrency environment, optimizing transactions and locking strategies can reduce lock competition.

In database optimization, indexing strategies should be selected according to query requirements: 1. When the query involves multiple columns and the order of conditions is fixed, use composite indexes; 2. When the query involves multiple columns but the order of conditions is not fixed, use multiple single-column indexes. Composite indexes are suitable for optimizing multi-column queries, while single-column indexes are suitable for single-column queries.

To optimize MySQL slow query, slowquerylog and performance_schema need to be used: 1. Enable slowquerylog and set thresholds to record slow query; 2. Use performance_schema to analyze query execution details, find out performance bottlenecks and optimize.

MySQL and SQL are essential skills for developers. 1.MySQL is an open source relational database management system, and SQL is the standard language used to manage and operate databases. 2.MySQL supports multiple storage engines through efficient data storage and retrieval functions, and SQL completes complex data operations through simple statements. 3. Examples of usage include basic queries and advanced queries, such as filtering and sorting by condition. 4. Common errors include syntax errors and performance issues, which can be optimized by checking SQL statements and using EXPLAIN commands. 5. Performance optimization techniques include using indexes, avoiding full table scanning, optimizing JOIN operations and improving code readability.


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