[collection not recommended] Redis learning notes

Redis cache database foundation summary Redis, remote dictionary service. What can you do? Data persistence: RDB, OF High efficiency, cache Publish subscribe system Map information analysis Timer, page views ... characteristic Diverse data types Persistence affair colony ... Things needed in learning Redis official website: http ...

Posted by Studio381 on Sun, 01 May 2022 22:29:16 +0300

Transaction opening, commit and rollback of MySQL database

A transaction is a user-defined sequence of database operations. These operations are either done or not done at all, and are an inseparable unit of work. Based on the atomicity, consistency, isolation and persistence characteristics of transactions, related data operations can be defined into a transaction. If no exception occurs during the ...

Posted by wblati on Sat, 30 Apr 2022 23:02:23 +0300

Basic syntax of MySQL database

Basic operation of MySQL database 1. Creation of database 1.1 create database Create database create database <Database name>   -- stay sql Statements are not case sensitive Use database use <Database name> Delete database drop database  <Database name> view the database show databases <Database name> 1.2 crea ...

Posted by IG88 on Sat, 30 Apr 2022 18:54:06 +0300

JAVA combat articles Simple application of the transaction manager that comes with Spring Programmatic transaction Declarative transaction, annotation declarative transaction, AspectJ annotation transaction

The transaction manager that comes with Spring 1. Programmatic transactions For details, please refer to the official documentation: https://www.docs4dev.com/docs/zh/spring-framework/5.1.3.RELEASE/reference/data-access.html#transaction-programmatic Advantages: no need for spring to proxy, generate proxy objects (reflection), better performanc ...

Posted by irkevin on Sat, 30 Apr 2022 15:40:21 +0300

Naming Specification for MySQL

1. Naming Specification 1.1 Specification for Library Construction Databases, tables, fields, indexes are all lowercase letters, and English words are underlined () Separate. 1.2 Table Field Specification The column design specification uses tinyint/int/bigint according to business area, which takes up 1/4/8 bytes, respectively. Use tinyint ...

Posted by Bramme on Sat, 30 Apr 2022 03:48:57 +0300

Record local installation oushudb - install zk and hdfs

Because the company is busy recently, I forgot to update it. Then I talked about it in the last article, The last article said This article describes some preparations for installing oushudb. This article mainly talks about the installation of corresponding components before installing oushudb. 1, Zookeper installation 1. Create a zkhostfile c ...

Posted by Chips on Sat, 30 Apr 2022 00:19:07 +0300

14_ Users and permissions

theory 1. User column The user column of the user table includes Host, user and password, which represent Host name, user name and password respectively. Where user and Host are the joint primary nodes of the user table. When establishing a connection between the user and the server, the user name, Host name and password in the entered ac ...

Posted by apulmca on Fri, 29 Apr 2022 09:42:09 +0300

Performance comparison test of random forest algorithm implementation: scikit-learn, Spark MLlib, DolphinDB, xgboost

Random forests are commonly used machine learning algorithms that can be used for both classification and regression problems. This article compares and tests the implementation of random forest algorithm on four platforms, scikit-learn, Spark MLlib, DolphinDB, and xgboost. Evaluation metrics include memory footprint, running speed, and classif ...

Posted by djroki on Fri, 29 Apr 2022 09:01:44 +0300

1. Introduction to FlashTsDB time series database

  Introduction to FlashTsDB time series database 1,What is FlashTsDB 1.1 Background With the continuous development of the Internet and the Internet of Things, the storage demand for massive data with time series characteristics is increasing, and TSDB (Time Series Database) has begun to receive more attention. Traditional commercial time-s ...

Posted by thestars on Fri, 29 Apr 2022 03:29:56 +0300

Mybatis complex query (many-to-many, one-to-many, many-to-one)

We know that it is very easy to complete single-table query in Mybatis, and multi-table query is a difficult point in the Mybatis framework, which needs to be mastered. 1. Many-to-many query There is a many-to-many relationship between users and groups, and the requirement is: find all group information by user id The database design ...

Posted by nonexistentera on Fri, 29 Apr 2022 03:20:50 +0300