mysql show status 指令查看信息详解
欢迎进入Linux社区论坛,与200万技术人员互动交流 >>进入 命令: show status; Aborted_clients 由于客户没有正确关闭连接已经死掉,已经放弃的连接数量。 Aborted_connects 尝试已经失败的MySQL服务器的连接的次数。 Connections 试图连接MySQL服务器的次数
欢迎进入Linux社区论坛,与200万技术人员互动交流 >>进入
命令: show status;
Aborted_clients 由于客户没有正确关闭连接已经死掉,已经放弃的连接数量。
Aborted_connects 尝试已经失败的MySQL服务器的连接的次数。
Connections 试图连接MySQL服务器的次数。
Created_tmp_tables 当执行语句时,已经被创造了的隐含临时表的数量。
Delayed_insert_threads 正在使用的延迟插入处理器线程的数量。
Delayed_writes 用INSERT DELAYED写入的行数。
Delayed_errors 用INSERT DELAYED写入的发生某些错误(可能重复键值)的行数。
Flush_commands 执行FLUSH命令的次数。
Handler_delete 请求从一张表中删除行的次数。
Handler_read_first 请求读入表中第一行的次数。
Handler_read_key 请求数字基于键读行。
Handler_read_next 请求读入基于一个键的一行的次数。
Handler_read_rnd 请求读入基于一个固定位置的一行的次数。
Handler_update 请求更新表中一行的次数。
Handler_write 请求向表中插入一行的次数。
Key_blocks_used 用于关键字缓存的块的数量。
Key_read_requests 请求从缓存读入一个键值的次数。
Key_reads 从磁盘物理读入一个键值的次数。
Key_write_requests 请求将一个关键字块写入缓存次数。
Key_writes 将一个键值块物理写入磁盘的次数。
Max_used_connections 同时使用的连接的最大数目。
Not_flushed_key_blocks 在键缓存中已经改变但是还没被清空到磁盘上的键块。
Not_flushed_delayed_rows 在INSERT DELAY队列中等待写入的行的数量。
Open_tables 打开表的数量。
Open_files 打开文件的数量。
Open_streams 打开流的数量(主要用于日志记载)
Opened_tables 已经打开的表的数量。
Questions 发往服务器的查询的数量。
Slow_queries 要花超过long_query_time时间的查询数量。
Threads_connected 当前打开的连接的数量。
Threads_running 不在睡眠的线程数量。
Uptime 服务器工作了多少秒。

MySQL index cardinality has a significant impact on query performance: 1. High cardinality index can more effectively narrow the data range and improve query efficiency; 2. Low cardinality index may lead to full table scanning and reduce query performance; 3. In joint index, high cardinality sequences should be placed in front to optimize query.

The MySQL learning path includes basic knowledge, core concepts, usage examples, and optimization techniques. 1) Understand basic concepts such as tables, rows, columns, and SQL queries. 2) Learn the definition, working principles and advantages of MySQL. 3) Master basic CRUD operations and advanced usage, such as indexes and stored procedures. 4) Familiar with common error debugging and performance optimization suggestions, such as rational use of indexes and optimization queries. Through these steps, you will have a full grasp of the use and optimization of MySQL.

MySQL's real-world applications include basic database design and complex query optimization. 1) Basic usage: used to store and manage user data, such as inserting, querying, updating and deleting user information. 2) Advanced usage: Handle complex business logic, such as order and inventory management of e-commerce platforms. 3) Performance optimization: Improve performance by rationally using indexes, partition tables and query caches.

SQL commands in MySQL can be divided into categories such as DDL, DML, DQL, DCL, etc., and are used to create, modify, delete databases and tables, insert, update, delete data, and perform complex query operations. 1. Basic usage includes CREATETABLE creation table, INSERTINTO insert data, and SELECT query data. 2. Advanced usage involves JOIN for table joins, subqueries and GROUPBY for data aggregation. 3. Common errors such as syntax errors, data type mismatch and permission problems can be debugged through syntax checking, data type conversion and permission management. 4. Performance optimization suggestions include using indexes, avoiding full table scanning, optimizing JOIN operations and using transactions to ensure data consistency.

InnoDB achieves atomicity through undolog, consistency and isolation through locking mechanism and MVCC, and persistence through redolog. 1) Atomicity: Use undolog to record the original data to ensure that the transaction can be rolled back. 2) Consistency: Ensure the data consistency through row-level locking and MVCC. 3) Isolation: Supports multiple isolation levels, and REPEATABLEREAD is used by default. 4) Persistence: Use redolog to record modifications to ensure that data is saved for a long time.

MySQL's position in databases and programming is very important. It is an open source relational database management system that is widely used in various application scenarios. 1) MySQL provides efficient data storage, organization and retrieval functions, supporting Web, mobile and enterprise-level systems. 2) It uses a client-server architecture, supports multiple storage engines and index optimization. 3) Basic usages include creating tables and inserting data, and advanced usages involve multi-table JOINs and complex queries. 4) Frequently asked questions such as SQL syntax errors and performance issues can be debugged through the EXPLAIN command and slow query log. 5) Performance optimization methods include rational use of indexes, optimized query and use of caches. Best practices include using transactions and PreparedStatemen

MySQL is suitable for small and large enterprises. 1) Small businesses can use MySQL for basic data management, such as storing customer information. 2) Large enterprises can use MySQL to process massive data and complex business logic to optimize query performance and transaction processing.

InnoDB effectively prevents phantom reading through Next-KeyLocking mechanism. 1) Next-KeyLocking combines row lock and gap lock to lock records and their gaps to prevent new records from being inserted. 2) In practical applications, by optimizing query and adjusting isolation levels, lock competition can be reduced and concurrency performance can be improved.


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

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Safe Exam Browser
Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.

MantisBT
Mantis is an easy-to-deploy web-based defect tracking tool designed to aid in product defect tracking. It requires PHP, MySQL and a web server. Check out our demo and hosting services.

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.

ZendStudio 13.5.1 Mac
Powerful PHP integrated development environment