INSERT查询的速度: 插入一个记录的时间由下列组成: 连接:(3) 发送查询给服务器:(2) 分析查询:(2) 插入记录:(1 x 记录大小) 插入索引:(1 x 索引) 关闭:(1) 这里的数字有点与总体时间成正比。这不考虑打开表的初始开销(它为每个并发运行的查询做一次)。
INSERT查询的速度:
插入一个记录的时间由下列组成:
连接:(3)
发送查询给服务器:(2)
分析查询:(2)
插入记录:(1 x 记录大小)
插入索引:(1 x 索引)
关闭:(1)
这里的数字有点与总体时间成正比。这不考虑打开表的初始开销(它为每个并发运行的查询做一次)。
表的大小以N log N (B 树)的速度减慢索引的插入。
加快插入的一些方法:
如果你同时从同一客户插入很多行,使用多个值表的INSERT语句。这比使用分开INSERT语句快(在一些情况中几倍)。
如果你从不同客户插入很多行,你能通过使用INSERT DELAYED语句得到更高的速度。
注意,用MyISAM,如果在表中没有删除的行,能在SELECT:s正在运行的同时插入行。
当从一个文本文件装载一个表时,使用LOAD DATA INFILE。这通常比使用很多INSERT语句快20倍。当表有很多索引时,有可能多做些工作使得LOAD DATA INFILE更快些。使用下列过程:
有选择地用CREATE TABLE创建表。例如使用mysql或Perl-DBI。
执行FLUSH TABLES,或外壳命令mysqladmin flush-tables。
使用myisamchk --keys-used=0 -rq /path/to/db/tbl_name。这将从表中删除所有索引的使用。
用LOAD DATA INFILE把数据插入到表中,这将不更新任何索引,因此很快。
如果你有myisampack并且想要压缩表,在它上面运行myisampack.
用myisamchk -r -q /path/to/db/tbl_name再创建索引。这将在将它写入磁盘前在内存中创建索引树,并且它更快,,因为避免大量磁盘寻道。结果索引树也被完美地平衡。
执行FLUSH TABLES,或外壳命令mysqladmin flush-tables。
这个过程将被构造进在MySQL的某个未来版本的LOAD DATA INFILE。
你可以锁定你的表以加速插入。
mysql> LOCK TABLES a WRITE;mysql> INSERT INTO a VALUES (1,23),(2,34),(4,33);mysql> INSERT INTO a VALUES (8,26),(6,29);mysql> UNLOCK TABLES;主要的速度差别是索引缓冲区仅被清洗到磁盘上一次,在所有INSERT语句完成后。一般有与有不同的INSERT语句那样夺的索引缓冲区清洗。如果你能用一个单个语句插入所有的行,锁定就不需要。锁定也将降低多连接测试的整体时间,但是对某些线程最大等待时间将上升(因为他们等待锁)。例如:
thread 1 does 1000 insertsthread 2, 3, and 4 does 1 insert
thread 5 does 1000 inserts如果你不使用锁定,2、3和4将在1和5前完成。如果你使用锁定,2、3和4将可能不在1或5前完成,但是整体时间应该快大约40%。因为INSERT, UPDATE和DELETE操作在MySQL中是很快的,通过为多于大约5次连续不断地插入或更新一行的东西加锁,你将获得更好的整体性能。如果你做很多一行的插入,你可以做一个LOCK TABLES,偶尔随后做一个UNLOCK TABLES(大约每1000行)以允许另外的线程存取表。这仍然将导致获得好的性能。当然,LOAD DATA INFILE对装载数据仍然是更快的。

The main difference between MySQL and SQLite is the design concept and usage scenarios: 1. MySQL is suitable for large applications and enterprise-level solutions, supporting high performance and high concurrency; 2. SQLite is suitable for mobile applications and desktop software, lightweight and easy to embed.

Indexes in MySQL are an ordered structure of one or more columns in a database table, used to speed up data retrieval. 1) Indexes improve query speed by reducing the amount of scanned data. 2) B-Tree index uses a balanced tree structure, which is suitable for range query and sorting. 3) Use CREATEINDEX statements to create indexes, such as CREATEINDEXidx_customer_idONorders(customer_id). 4) Composite indexes can optimize multi-column queries, such as CREATEINDEXidx_customer_orderONorders(customer_id,order_date). 5) Use EXPLAIN to analyze query plans and avoid

Using transactions in MySQL ensures data consistency. 1) Start the transaction through STARTTRANSACTION, and then execute SQL operations and submit it with COMMIT or ROLLBACK. 2) Use SAVEPOINT to set a save point to allow partial rollback. 3) Performance optimization suggestions include shortening transaction time, avoiding large-scale queries and using isolation levels reasonably.

Scenarios where PostgreSQL is chosen instead of MySQL include: 1) complex queries and advanced SQL functions, 2) strict data integrity and ACID compliance, 3) advanced spatial functions are required, and 4) high performance is required when processing large data sets. PostgreSQL performs well in these aspects and is suitable for projects that require complex data processing and high data integrity.

The security of MySQL database can be achieved through the following measures: 1. User permission management: Strictly control access rights through CREATEUSER and GRANT commands. 2. Encrypted transmission: Configure SSL/TLS to ensure data transmission security. 3. Database backup and recovery: Use mysqldump or mysqlpump to regularly backup data. 4. Advanced security policy: Use a firewall to restrict access and enable audit logging operations. 5. Performance optimization and best practices: Take into account both safety and performance through indexing and query optimization and regular maintenance.

How to effectively monitor MySQL performance? Use tools such as mysqladmin, SHOWGLOBALSTATUS, PerconaMonitoring and Management (PMM), and MySQL EnterpriseMonitor. 1. Use mysqladmin to view the number of connections. 2. Use SHOWGLOBALSTATUS to view the query number. 3.PMM provides detailed performance data and graphical interface. 4.MySQLEnterpriseMonitor provides rich monitoring functions and alarm mechanisms.

The difference between MySQL and SQLServer is: 1) MySQL is open source and suitable for web and embedded systems, 2) SQLServer is a commercial product of Microsoft and is suitable for enterprise-level applications. There are significant differences between the two in storage engine, performance optimization and application scenarios. When choosing, you need to consider project size and future scalability.

In enterprise-level application scenarios that require high availability, advanced security and good integration, SQLServer should be chosen instead of MySQL. 1) SQLServer provides enterprise-level features such as high availability and advanced security. 2) It is closely integrated with Microsoft ecosystems such as VisualStudio and PowerBI. 3) SQLServer performs excellent in performance optimization and supports memory-optimized tables and column storage indexes.


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