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How SpringBoot integrates Druid and Redis

1. Integrate Druid 1.1 Introduction to Druid A large part of Java programs need to operate the database. In order to improve performance, when operating the database, you have to use the database connection pool. Druid is a database connection pool implementation on Alibaba's open source platform. It combines the advantages of DB pools such as C3P0 and DBCP, and also adds log monitoring. Druid can monitor DB pool connections and SQL execution very well. It is a DB connection pool designed for monitoring. 1.2 Add Druid data source dependency com.alibabadruid-spring-boot-starter1.2.81.3 Use Druid data source server:port:808

May 31, 2023 pm 10:31 PM

redisSpringBootdruid

How to use Bitmap in Redis

In the daily development process, there are often some bool type data that need to be accessed. For example, if you record the number of times a user has checked in within a year, it will be 1 if you have signed in, and 0 if you have not signed in. If key-value is used for storage, each user will be recorded 365 times. When there are hundreds of millions of users, the storage space required will be very huge. To solve this problem, you can use bitmaps in redis. Bitmap also belongs to the string data type. A string type value in Redis can store up to 512MB of content. Each string is composed of multiple bytes, and each byte is composed of 8 Bits. The bitmap structure uses "bits" to achieve storage. It achieves the purpose of data access by setting the bits to 0 or 1.

May 31, 2023 pm 09:40 PM

redisbitmap

How Java uses Lettuce client to execute commands in Redis master-slave mode

1The concept of redis master-slave replication In a multi-machine environment, a redis service receives write commands. When its own data and status change, it copies them to one or more redis. This mode is called master-slave replication. In redis, use the command salveof to let the redis executing the command copy the data and status of another redis. We call the main server master and the slave server slave. Master-slave replication ensures that data will be replicated when the network is abnormal and disconnected. When the network is normal, the master will keep the slave updated by sending commands. The updates include client writes, key expiration or eviction and other network abnormalities. The master is connected to the slave.

May 31, 2023 pm 09:05 PM

Javaredislettuce

How to quickly understand Redis

1. Redis is one of the most popular NoSQL databases now. It is an open source key-value storage database written in ANSIC, containing a variety of data structures, supporting network, memory-based, and optional persistence. By default, Redis is a cache memory that is called for database use. It utilizes volatile memory and can provide users with complete persistence options and support for other data types. 2. The application scenarios of Redis include: cache system, counter, message queue system, ranking list, social network and real-time system. 3. Redis can use client APIs developed in all popular languages, such as C language, Ruby, Python, Java, JavaScript, etc.

May 31, 2023 pm 08:55 PM

redis

What is the algorithm formula for Redis bloom filter size?

1. Introduction to the client: Does this key exist? Server: Does not exist/don’t know Essentially, Bloom filter is a data structure, a relatively clever probabilistic data structure. It features efficient insertion and querying. But when we want to check whether a key exists in a certain structure, by using a Bloom filter, we can quickly learn that "this key must not exist or may exist." Compared with traditional data structures such as List, Set, and Map, it is more efficient and takes up less space, but the results it returns are probabilistic and inaccurate. Bloom filters are only used to test membership in a set. A classic example of using Bloom filters is to reduce expensive disk (or network) lookups for non-existent keys.

May 31, 2023 pm 08:17 PM

redis

How Redis saves memory

First of all, this application that uses picture ID to check user UID has the following requirements: the query speed must be fast enough, and all the data must be stored in the memory. It is best to have an EC2 high-memory model that can store it (17GB or 34GB, 68GB is too wasteful) supports persistence, so that there is no need to warm up after the server is restarted. First of all, it negates the database storage solution. They maintain the KISS principle (Keep It Simple and Stupid), because this application does not use database updates at all. functions, transaction functions and related queries, etc., so there is no need to choose and maintain a database for these unused functions. So they chose Redis, Redis

May 31, 2023 pm 08:04 PM

redis

How to solve Redis cache penetration and cache avalanche problems

How to solve the problem of Redis cache penetration and cache avalanche. Cache avalanche: Since the cache layer carries a large number of requests, it effectively protects the storage layer. However, if the cache layer cannot provide services for some reasons, such as the Redis node hangs up and the hotspot keys are all Failure. In these cases, all requests will be made directly to the database, which may cause database downtime. To prevent and solve the cache avalanche problem, you can start from the following three aspects: 1. Use Redis high-availability architecture: use Redis cluster to ensure that the Redis service will not hang up. 2. Inconsistent cache time: add a cache expiration time. Random values to avoid collective failure 3. Current limiting and downgrading strategy: There are certain filings, such as personalized recommendation services

May 31, 2023 pm 07:45 PM

redis

Redis distributed lock instance analysis

Overview of distributed locks In a multi-threaded environment, in order to ensure that a code block can only be accessed by one thread at the same time, in Java we can generally use synchronized syntax and ReetrantLock to ensure that this is actually a local lock method. But now companies are adopting distributed architecture. In a distributed environment, how to ensure that threads on different nodes execute simultaneously? Therefore, distributed locks are introduced, which are a way to control mutually exclusive access to shared resources between distributed systems. In a distributed system, multiple services are deployed on multiple machines. When a user on the client initiates a data insertion request, if there is no distributed lock mechanism guarantee, then multiple services on the multiple machines may perform concurrently. Penetration fuck

May 31, 2023 pm 07:32 PM

redis

How to implement Redis String operation in php

String operation //Set key value: Return true successfully, otherwise return false$redis->set('mystr','Welcome!');//Get key value: Return String type key value successfully, if the key does not exist or is not String type returns false $ret=$redis->get('mystr');//Start from the specified offset of the string stored in a key, replace it with another specified string, and successfully return the new string after replacement The length of the string. $ret=$r

May 31, 2023 pm 07:13 PM

PHPredisstring

What are the commands to check the redis version on Linux system?

1. Use the "redis-server-version" command or "redis-server-v", redis-server is in the src directory in the redis installation directory [root@db148redis-2.6.10]#src/redis-server--versionRedisserverv= 2.6.10sha=00000000:0malloc=jemalloc-3.2.0bits=32[root@db148redis-2.6.10]#./src/redis-server-vRedisserv

May 31, 2023 pm 06:43 PM

Linuxredis

How to deploy redis cluster in k8s

redis cluster building 1.1 Use redis-cli to create a cluster #View the ipkubectlgetpod-njxbp-owide corresponding to the redis pod>NAMEREADYSTATUSRESARTSAGEIPNODENOMINATEDNODEREADINESSGATESredis-01/1Running018h10.168.235.196k8s-masterredis-11/1Running018h10.168.235.225k 8s-masterredis-21/1Running018h10.168 .

May 31, 2023 pm 05:25 PM

redisk8s

What are the basic data query commands in redis?

(1) Key query 1. Query all keyKEY*2. Query the keyKEY* character* that contains a certain character. For example, query the key that contains the character chen. KEY*chen*3. Query the type of key TYPEkey4. Query whether a certain key exists EXISTSkey ( 2) Five data type query commands 1. String query 1.1 Query the value of string type key GETstring_key1.2 Query the length of string type key STRLENstring_key1.3 Query the value of multiple string type keys MGETstring_key1[string_key2..... ]2.hash

May 31, 2023 pm 05:19 PM

redis

What are the Redis interview questions and answers?

Let’s talk about the basic data types of Redis. Strings: Redis does not directly use the traditional string representation of C language, but implements its own abstract type called simple dynamic string SDS. The string in C language does not record its own length information, but SDS saves the length information, which reduces the time to obtain the string length from O(N) to O(1), while avoiding buffer overflow and reducing the need to modify characters. The number of memory reallocations required for the length of the string. Linked list linkedlist: The redis linked list is a two-way acyclic linked list structure. Many publish and subscribe, slow query, and monitor functions are implemented using linked lists. The nodes of each linked list are represented by a listNode structure. Each node has

May 31, 2023 pm 04:55 PM

redis

Docker installation Redis instance analysis

1. Start dockersystemctlstartdocker2. Pull the redis image dockerpullredis:5.0.3. Note that if the version number is not specified, pull the latest version. 3. Create a local redis mounting directory mkdir-p/root/redis/data/root/redis/ conf4. Create the redis.conf file touch/root/redis/data/root/redis/conf/redis.conf5. Modify the redis.conf file download link: https://www.lanzous.com/i68hla

May 31, 2023 pm 04:52 PM

Dockerredis