redis安装方法见:初识Redis邂逅 安装环境: [root@localhost redis]# redis-server --versionRedis server v=2.8.7 sha=00000000:0 malloc=jemalloc-3.2.0 bits=32 build=df8b796b6fcf0127[root@localhost redis]# cat /proc/versionLinux version 2.6.18-9
redis安装方法见:初识Redis——邂逅
安装环境:[root@localhost redis]# redis-server --version Redis server v=2.8.7 sha=00000000:0 malloc=jemalloc-3.2.0 bits=32 build=df8b796b6fcf0127 [root@localhost redis]# cat /proc/version Linux version 2.6.18-92.el5 (mockbuild@builder16.centos.org) (gcc version 4.1.2 20071124 (Red Hat 4.1.2-42)) #1 SMP Tue Jun 10 18:49:47 EDT 20081、复制配置文件
#master配置文件 cp redis.conf redis-master.conf #slave配置文件 cp redis.conf redis-slave.conf #备份配置文件 cp redis.conf redis-bak.conf2、修改配置文件
#master配置文件 #保证PID文件区分,PID文件主要用于保证守护进程单例运行 pidfile /var/run/redis-master.pid #区分LOG文件 logfile "/data/redis/6379/log/redis.log" #区分持久化文件 dir /data/redis/6379/data #区分端口 port 6379 #slave配置文件 pidfile /var/run/redis-slave.pid logfile "/data/redis/6380/log/redis.log" dir /data/redis/6380/data port 6380 slaveof 127.0.0.1 6379 #如果为yes,slave实例只读,如果为no,slave实例可读可写。默认 slave-read-only yes3、启动
redis-server /etc/redis/redis-master.conf redis-server /etc/redis/redis-slave.conf4、验证 master启动日志
[root@localhost redis]# cat /data/redis/6379/log/redis.log [24787] 13 Sep 10:39:45.143 * Max number of open files set to 10032 [24787] 13 Sep 10:39:45.145 # Warning: 32 bit instance detected but no memory limit set. Setting 3 GB maxmemory limit with 'noeviction' policy now. _._ _.-``__ ''-._ _.-`` `. `_. ''-._ Redis 2.8.7 (00000000/0) 32 bit .-`` .-```. ```\/ _.,_ ''-._ ( ' , .-` | `, ) Running in stand alone mode |`-._`-...-` __...-.``-._|'` _.-'| Port: 6379 | `-._ `._ / _.-' | PID: 24787 `-._ `-._ `-./ _.-' _.-' |`-._`-._ `-.__.-' _.-'_.-'| | `-._`-._ _.-'_.-' | http://redis.io `-._ `-._`-.__.-'_.-' _.-' |`-._`-._ `-.__.-' _.-'_.-'| | `-._`-._ _.-'_.-' | `-._ `-._`-.__.-'_.-' _.-' `-._ `-.__.-' _.-' `-._ _.-' `-.__.-' [24787] 13 Sep 10:39:45.146 # Server started, Redis version 2.8.7 [24787] 13 Sep 10:39:45.146 # WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect. [24787] 13 Sep 10:39:45.146 * The server is now ready to accept connections on port 6379 [24787] 13 Sep 10:40:54.342 * DB saved on disk [24787] 13 Sep 10:42:50.581 * Slave asks for synchronization [24787] 13 Sep 10:42:50.581 * Full resync requested by slave. [24787] 13 Sep 10:42:50.581 * Starting BGSAVE for SYNC [24787] 13 Sep 10:42:50.582 * Background saving started by pid 24816 [24816] 13 Sep 10:42:50.586 * DB saved on disk [24816] 13 Sep 10:42:50.587 * RDB: 0 MB of memory used by copy-on-write [24787] 13 Sep 10:42:50.673 * Background saving terminated with success [24787] 13 Sep 10:42:50.673 * Synchronization with slave succeeded [24787] 13 Sep 10:47:04.093 * DB saved on diskslave 启动日志
[root@localhost redis]# cat /data/redis/6380/log/redis.log [24813] 13 Sep 10:42:50.578 * Max number of open files set to 10032 [24813] 13 Sep 10:42:50.579 # Warning: 32 bit instance detected but no memory limit set. Setting 3 GB maxmemory limit with 'noeviction' policy now. _._ _.-``__ ''-._ _.-`` `. `_. ''-._ Redis 2.8.7 (00000000/0) 32 bit .-`` .-```. ```\/ _.,_ ''-._ ( ' , .-` | `, ) Running in stand alone mode |`-._`-...-` __...-.``-._|'` _.-'| Port: 6380 | `-._ `._ / _.-' | PID: 24813 `-._ `-._ `-./ _.-' _.-' |`-._`-._ `-.__.-' _.-'_.-'| | `-._`-._ _.-'_.-' | http://redis.io `-._ `-._`-.__.-'_.-' _.-' |`-._`-._ `-.__.-' _.-'_.-'| | `-._`-._ _.-'_.-' | `-._ `-._`-.__.-'_.-' _.-' `-._ `-.__.-' _.-' `-._ _.-' `-.__.-' [24813] 13 Sep 10:42:50.580 # Server started, Redis version 2.8.7 [24813] 13 Sep 10:42:50.580 # WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect. [24813] 13 Sep 10:42:50.580 * The server is now ready to accept connections on port 6380 [24813] 13 Sep 10:42:50.580 * Connecting to MASTER 127.0.0.1:6379 [24813] 13 Sep 10:42:50.580 * MASTER <-> SLAVE sync started [24813] 13 Sep 10:42:50.580 * Non blocking connect for SYNC fired the event. [24813] 13 Sep 10:42:50.581 * Master replied to PING, replication can continue... [24813] 13 Sep 10:42:50.581 * Partial resynchronization not possible (no cached master) [24813] 13 Sep 10:42:50.583 * Full resync from master: 9ef3d846e366f7643db9e9250b508d64a34c1079:1 [24813] 13 Sep 10:42:50.673 * MASTER <-> SLAVE sync: receiving 31 bytes from master [24813] 13 Sep 10:42:50.673 * MASTER <-> SLAVE sync: Flushing old data [24813] 13 Sep 10:42:50.673 * MASTER <-> SLAVE sync: Loading DB in memory [24813] 13 Sep 10:42:50.674 * MASTER <-> SLAVE sync: Finished with success [24813] 13 Sep 10:47:04.096 * DB saved on disk数据同步验证:
[root@localhost redis]# redis-cli 127.0.0.1:6379> set name test OK 127.0.0.1:6379> save OK [root@localhost redis]# redis-cli -p 6380 127.0.0.1:6380> keys * 1) "name"

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.


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