有关mysql的一些小技巧,有需要的朋友可以参考下
1. 大批量乱序数据导入InnoDB很慢如何解决?
InnoDB因为主键聚集索引的关系,如果没有主键或者主键非序列的情况下,导入会越来越慢,如何快速的迁移数据到InnoDB?借助MyISAM的力量 是很靠谱的,先关闭InnoDB的Buffer Pool,把内存空出来,建一张没有任何索引的MyISAM表,然后只管插入吧,concurrent_insert=2,在文件末尾并发插入,速度刚刚 的,插入完成后,ALTER TABLE把索引加上,记得还有ENGINE=InnoDB,就把MyISAM转到InnoDB了,这样的速度远比直接往InnoDB里插乱序数据来得快。
2. 在基于ROW的双Master复制下,如何快速大批量订正?
在AB的双Master结构下,假设只有一台提供服务,这是我们常用的架构,需要大批量订正数据,如何做最快?用存储过程一批批提交?这有很多的限制,有时候并不可以把一条或多条SQL拆成几段,怎么办呢?binlog不是很好的工具嘛?! ROW格式的binlog,Slave在应用时是直接使用Handler API,并没有走SQL解析,速度非常快,基本上是IO操作了,那么我们可以在备库上直接执行订正SQL,产生的ROW binlog传到主机,就会很快订正完,基本上都比写存储过程快。
3. ROW格式Replication如何实现不带库名的replicate-do-db?
虽然MySQL有replicate-do-db这个参数,但是在ROW格式的binlog下必须使用”db.table”的方式才能生效,USE对ROW格式是无效的。现在我有一个Instance,只需要复制Master的某几个库,但是是ROW格式,SQL都 没有使用db前缀,怎么办?可以这么做,把主库需要的库导出来,不需要的库导出结构即可,在Slave导入这些数据及结构,配置skip-slave- errors=all,这样Master复制过来的binlog,只要发现有库有表结构,就不会报找不到表,就不会阻塞复制,但是 UPDATE/DELETE过来没有数据也会被跳过错误,间接的实现了replicate-do-db。
4. AB–>C–>D结构切换到AB, CD结构出现Slave_lag一直增常如何避免?
这种情况常见与一个双Master集群分离出一套双Master集群,例如从原集群分离一部分库。过快的切换B–>C到CD容易导致主备出现slave_lag,并且一直增长,原因在于AB集群产生的SQL,随同server_id带到了C–>D这个M-S中,当A,B产生的SQL在C,D还没消化完成就CHANGE MASTER为CD时,会导致这写SQL在C,D之间来回传输,因为C,D都认为这个SQL不是自己产生的,因而不销毁,自己执行后写入binlog,于是Slave_Lag就一直增长。
避免的方法很简单,部分写切到C后,先断开B–>C的复制,等一会,看D上已经没有Slave_Lag了,再CHANGE MASTER为CD,这样A,B传过来的SQL都消化完了。
5. 表中存在很多重复数据时,如何删除这些重复数据最快?
在需要给表中某些字段加唯一索引时,而字段中又存在需要重复清理数据的问题,不少DBA都应该遇到过。一般在处理时总是想在数据库中只保留一条,其他的删除,但是这样的SQL写出来总是效率不高,怎么办?其实可以转换思路,把重复的都选出一条出来,存到一张临时表,然后删除原表中所有存在重复的,再把临时表的数据库全部插入原库,这是比较通用并且高效的做法。

InnoDBBufferPool reduces disk I/O by caching data and indexing pages, improving database performance. Its working principle includes: 1. Data reading: Read data from BufferPool; 2. Data writing: After modifying the data, write to BufferPool and refresh it to disk regularly; 3. Cache management: Use the LRU algorithm to manage cache pages; 4. Reading mechanism: Load adjacent data pages in advance. By sizing the BufferPool and using multiple instances, database performance can be optimized.

Compared with other programming languages, MySQL is mainly used to store and manage data, while other languages such as Python, Java, and C are used for logical processing and application development. MySQL is known for its high performance, scalability and cross-platform support, suitable for data management needs, while other languages have advantages in their respective fields such as data analytics, enterprise applications, and system programming.

MySQL is worth learning because it is a powerful open source database management system suitable for data storage, management and analysis. 1) MySQL is a relational database that uses SQL to operate data and is suitable for structured data management. 2) The SQL language is the key to interacting with MySQL and supports CRUD operations. 3) The working principle of MySQL includes client/server architecture, storage engine and query optimizer. 4) Basic usage includes creating databases and tables, and advanced usage involves joining tables using JOIN. 5) Common errors include syntax errors and permission issues, and debugging skills include checking syntax and using EXPLAIN commands. 6) Performance optimization involves the use of indexes, optimization of SQL statements and regular maintenance of databases.

MySQL is suitable for beginners to learn database skills. 1. Install MySQL server and client tools. 2. Understand basic SQL queries, such as SELECT. 3. Master data operations: create tables, insert, update, and delete data. 4. Learn advanced skills: subquery and window functions. 5. Debugging and optimization: Check syntax, use indexes, avoid SELECT*, and use LIMIT.

MySQL efficiently manages structured data through table structure and SQL query, and implements inter-table relationships through foreign keys. 1. Define the data format and type when creating a table. 2. Use foreign keys to establish relationships between tables. 3. Improve performance through indexing and query optimization. 4. Regularly backup and monitor databases to ensure data security and performance optimization.

MySQL is an open source relational database management system that is widely used in Web development. Its key features include: 1. Supports multiple storage engines, such as InnoDB and MyISAM, suitable for different scenarios; 2. Provides master-slave replication functions to facilitate load balancing and data backup; 3. Improve query efficiency through query optimization and index use.

SQL is used to interact with MySQL database to realize data addition, deletion, modification, inspection and database design. 1) SQL performs data operations through SELECT, INSERT, UPDATE, DELETE statements; 2) Use CREATE, ALTER, DROP statements for database design and management; 3) Complex queries and data analysis are implemented through SQL to improve business decision-making efficiency.

The basic operations of MySQL include creating databases, tables, and using SQL to perform CRUD operations on data. 1. Create a database: CREATEDATABASEmy_first_db; 2. Create a table: CREATETABLEbooks(idINTAUTO_INCREMENTPRIMARYKEY, titleVARCHAR(100)NOTNULL, authorVARCHAR(100)NOTNULL, published_yearINT); 3. Insert data: INSERTINTObooks(title, author, published_year)VA


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