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Technical Articles

Database

What to do if redis memory is full

Methods to deal with the full memory of Redis: Evicting policy: volatile-lru, volatile-ttl, allkeys-lru, allkeys-random to increase maxmemory to enable memory obsolete: config set maxmemory-policy noeviction Manually delete data: del key, flushall usage persistence: save Upgrade Redis version Note: Data eviction may cause data loss. Please weigh the pros and cons before implementing any policy and monitor memory usage regularly.

Apr 10, 2025 pm 08:42 PM

redis 数据丢失键值对

How to use redis lock

Using Redis to lock operations requires obtaining the lock through the SETNX command, and then using the EXPIRE command to set the expiration time. The specific steps are: (1) Use the SETNX command to try to set a key-value pair; (2) Use the EXPIRE command to set the expiration time for the lock; (3) Use the DEL command to delete the lock when the lock is no longer needed.

Apr 10, 2025 pm 08:39 PM

redis 键值对

How did the Redis Sentinel cooperate

Redis Sentinel achieves high availability by coordinating work to monitor and manage Redis instances. Key tasks include: Monitoring instance election leader performs failover processing configuration changes Sentinels communicate via the Gossip protocol. For optimal collaboration, it is recommended to deploy at least three sentinel instances, select different hosts, and monitor them.

Apr 10, 2025 pm 08:36 PM

redis

How to set the redis counter

The Redis counter is created by the INCR command and will be automatically initialized to 0 if it does not exist. The counter value can be obtained through the GET command and the counter is incremented and decremented using the INCR and DECR commands, respectively.

Apr 10, 2025 pm 08:33 PM

redis

How to unlock the full memory of Redis

Solutions to Redis full memory problems include: Identify the cause of full memory: Slow client memory leak configuration errors Take a solution: Reduce dataset optimization client performance Fix memory leak adjustment maxmemory configuration avoid emergency situations: Enable LRU expulsion policy Use AOF persistence settings notifications

Apr 10, 2025 pm 08:30 PM

redis

How to read the source code of redis

The best way to understand Redis source code is to go step by step: get familiar with the basics of Redis. Select a specific module or function as the starting point. Start with the entry point of the module or function and view the code line by line. View the code through the function call chain. Be familiar with the underlying data structures used by Redis. Identify the algorithm used by Redis.

Apr 10, 2025 pm 08:27 PM

redis

How to solve data loss with redis

Redis data loss causes include memory failures, power outages, human errors, and hardware failures. The solutions are: 1. Store data to disk with RDB or AOF persistence; 2. Copy to multiple servers for high availability; 3. HA with Redis Sentinel or Redis Cluster; 4. Create snapshots to back up data; 5. Implement best practices such as persistence, replication, snapshots, monitoring, and security measures.

Apr 10, 2025 pm 08:24 PM

redis 数据丢失

How to log in remotely with redis

There are two ways to log in to Redis remotely: forwarding through SSH port: After creating an SSH channel locally, connect to the local port to log in. Use Redis Sentinel: Install Redis Sentinel, configure configuration files, start Sentinel, and connect to the Redis master node after accessing the management interface.

Apr 10, 2025 pm 08:21 PM

redis

How to solve high concurrency with redis

Redis provides a variety of high concurrency solutions: 1. Cluster sharding data to improve throughput and fault tolerance; 2. Replication ensures data availability and improves read performance; 3. Pipeline reduces network overhead and improves throughput; 4. Transactions ensure atomicity to prevent data inconsistencies; 5. Lua scripts reduce communication and improves performance; 6. Publish/subscribe to achieve efficient real-time data transmission; 7. Current limit protects the server from overload. When choosing a plan, the applicability of clustering, replication, pipelines, transactions, Lua scripts, publish/subscribe, and current limit should be considered based on needs.

Apr 10, 2025 pm 08:18 PM

redis 并发请求

How to implement multi-threading redis

Redis 4.0 introduces a multi-threading mechanism to improve concurrent processing capabilities and reduce latency. This architecture contains IO threads and worker threads that get requests from the queue and execute Redis commands. The advantages of multithreading include improving concurrent processing capabilities, reducing latency and improving resource utilization. But it should be noted that it may bring about data consistency problems, increased resource consumption and thread safety problems.

Apr 10, 2025 pm 08:15 PM

redis

How to start the server with redis

The steps to start a Redis server include: Install Redis according to the operating system. Start the Redis service via redis-server (Linux/macOS) or redis-server.exe (Windows). Use the redis-cli ping (Linux/macOS) or redis-cli.exe ping (Windows) command to check the service status. Use a Redis client, such as redis-cli, Python, or Node.js, to access the server.

Apr 10, 2025 pm 08:12 PM

linux python redis macos 系统安装

What to do if redis crashes

Redis downtime handling guide: Diagnostic problems: Check the process running status and log errors, and check the status through commands. Recover data: Recover from backup, AOF, or RDB files. Prevent data loss: Enable persistence, use replication, and configure automatic failover. Optimize performance: Adjust configuration, use modules, and monitor indicators. Avoid downtime: Update Redis, maintain hardware/OS, use load balancers, test regularly.

Apr 10, 2025 pm 08:09 PM

redis 数据丢失

How to use redis

Using the Redis Java library requires: 1. Add dependencies (Jedis 3.6.3); 2. Connect to the Redis server (specify host and port); 3. Perform basic operations (set/get values, check whether keys exist, delete keys); 4. Perform complex operations (hash tables, lists, collections, ordered collections); 5. Publish/subscribe to messages (using JedisPubSub); 6. Close the connection (Jedis.close()).

Apr 10, 2025 pm 08:06 PM

redis

How to clear data with redis

The following two methods can be used to clear data in Redis: FLUSHALL command: Delete all keys and values in the database. CONFIG RESETSTAT command: Reset all states of the database (including keys, values, and other statistics).

Apr 10, 2025 pm 08:03 PM

redis