前言
索引加快了检索的速度，但是却降低了数据列里插入、删除以及修改数值的速度。也就是说，索引降低了许多涉及写入的操作速度。之所以出现这种情况，是由于写入一条数据不仅仅是要写入到数据行，还需要所有的索引都作出相应的改变如更新或是重新编排。MySQL在为检索生成一个执行方案时候，要仔细对索引进行计算，创建过多的索引对查询优化程序就加上了更多的工作，而且当你有太多的索引的时候，MySQL还有可能无法选出最好的索引来使用。于是在选择索引的时候，需要采取一些策略。
策略1
在选择索引列的时候，尽量为用搜索、分类或者分组的数据列编制索引，不要为作为输出的数据列编制索引。换句话说，最合适有索引的数据列是那些在where字句中出现的数据列，在连接字句中给出的数据列、或是在order by或是group by子句中出现的数据列。
策略2
综合考虑数据列的维度势。数据列的维度，等于它所容纳的非重复值的个数。
策略3
尽量选择短小的值进行索引
短小的值可以让比较操作更快完成，加快索引查询速度。
短小的值可以让索引的体积更小，减少磁盘I/O活动
短小的键值意味着键缓存里的索引块可以容纳更多的键值，让MySQL可以在内存中容纳更多的键，这样较少了I/O活动的概率。
InnoDB存储引擎采用的聚族索引。所谓的聚族索引就是把数据行和主键索引集中保存在一起，其他的索引都是二级索引，它们保存着主键值和二级索引值。对于二级索引查找过程是先通过二级索引找到主键，然后通过主键找到对应的数据。选择短小的值进行索引，可以减少二级索引占据的空间。
策略4
为字符串值的前缀添加索引
如果打算给一个字符串列添加索引，尽可能的给出前缀长度。
策略5
不要建立过多的索引
How do you handle database upgrades in MySQL?Apr 30, 2025 am 12:28 AMThe steps for upgrading MySQL database include: 1. Backup the database, 2. Stop the current MySQL service, 3. Install the new version of MySQL, 4. Start the new version of MySQL service, 5. Recover the database. Compatibility issues are required during the upgrade process, and advanced tools such as PerconaToolkit can be used for testing and optimization.
What are the different backup strategies you can use for MySQL?Apr 30, 2025 am 12:28 AMMySQL backup policies include logical backup, physical backup, incremental backup, replication-based backup, and cloud backup. 1. Logical backup uses mysqldump to export database structure and data, which is suitable for small databases and version migrations. 2. Physical backups are fast and comprehensive by copying data files, but require database consistency. 3. Incremental backup uses binary logging to record changes, which is suitable for large databases. 4. Replication-based backup reduces the impact on the production system by backing up from the server. 5. Cloud backups such as AmazonRDS provide automation solutions, but costs and control need to be considered. When selecting a policy, database size, downtime tolerance, recovery time, and recovery point goals should be considered.
What is MySQL clustering?Apr 30, 2025 am 12:28 AMMySQLclusteringenhancesdatabaserobustnessandscalabilitybydistributingdataacrossmultiplenodes.ItusestheNDBenginefordatareplicationandfaulttolerance,ensuringhighavailability.Setupinvolvesconfiguringmanagement,data,andSQLnodes,withcarefulmonitoringandpe
How do you optimize database schema design for performance in MySQL?Apr 30, 2025 am 12:27 AMOptimizing database schema design in MySQL can improve performance through the following steps: 1. Index optimization: Create indexes on common query columns, balancing the overhead of query and inserting updates. 2. Table structure optimization: Reduce data redundancy through normalization or anti-normalization and improve access efficiency. 3. Data type selection: Use appropriate data types, such as INT instead of VARCHAR, to reduce storage space. 4. Partitioning and sub-table: For large data volumes, use partitioning and sub-table to disperse data to improve query and maintenance efficiency.
How can you optimize MySQL performance?Apr 30, 2025 am 12:26 AMTooptimizeMySQLperformance,followthesesteps:1)Implementproperindexingtospeedupqueries,2)UseEXPLAINtoanalyzeandoptimizequeryperformance,3)Adjustserverconfigurationsettingslikeinnodb_buffer_pool_sizeandmax_connections,4)Usepartitioningforlargetablestoi
How to use MySQL functions for data processing and calculationApr 29, 2025 pm 04:21 PMMySQL functions can be used for data processing and calculation. 1. Basic usage includes string processing, date calculation and mathematical operations. 2. Advanced usage involves combining multiple functions to implement complex operations. 3. Performance optimization requires avoiding the use of functions in the WHERE clause and using GROUPBY and temporary tables.
An efficient way to batch insert data in MySQLApr 29, 2025 pm 04:18 PMEfficient methods for batch inserting data in MySQL include: 1. Using INSERTINTO...VALUES syntax, 2. Using LOADDATAINFILE command, 3. Using transaction processing, 4. Adjust batch size, 5. Disable indexing, 6. Using INSERTIGNORE or INSERT...ONDUPLICATEKEYUPDATE, these methods can significantly improve database operation efficiency.
Steps to add and delete fields to MySQL tablesApr 29, 2025 pm 04:15 PMIn MySQL, add fields using ALTERTABLEtable_nameADDCOLUMNnew_columnVARCHAR(255)AFTERexisting_column, delete fields using ALTERTABLEtable_nameDROPCOLUMNcolumn_to_drop. When adding fields, you need to specify a location to optimize query performance and data structure; before deleting fields, you need to confirm that the operation is irreversible; modifying table structure using online DDL, backup data, test environment, and low-load time periods is performance optimization and best practice.
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
ZendStudio 13.5.1 Mac
Powerful PHP integrated development environment
mPDF
mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),
SecLists
SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.
SAP NetWeaver Server Adapter for Eclipse
Integrate Eclipse with SAP NetWeaver application server.
MinGW - Minimalist GNU for Windows
This project is in the process of being migrated to osdn.net/projects/mingw, you can continue to follow us there. MinGW: A native Windows port of the GNU Compiler Collection (GCC), freely distributable import libraries and header files for building native Windows applications; includes extensions to the MSVC runtime to support C99 functionality. All MinGW software can run on 64-bit Windows platforms.
