Category:Database

  • Learning spring cloud ribbon takes you from 0 to 1

    Time:2020-9-21

    1、 The role of ribbon in microservice 1. What is ribbon 1. Ribbon is based on HTTP and TCPClient < font color = Red > < font > Load Balancing tool, which is based on Netflix ribbon 2. It is not deployed independently as spring cloud service registry, configuration center and API gateway, but it […]

  • Double write consistency of redis cache and database

    Time:2020-9-21

    Article structure This paper consists of the following three parts1. Explain cache update strategy2. Analyze the disadvantages of each strategy3. The improvement scheme is given in view of the shortcomings text In theory, setting the expiration time of cache is the solution to ensure the final consistency. In this scheme, we can set the expiration […]

  • More complex SQL statements: Oracle DDL and DML

    Time:2020-9-21

    DDL: changes have been made to the table or its properties Create: create table create user create view Create table create table student(id int,score int) ; There can be no space between the student and the bracket Create user create user liuyifei identified by 4852396; Drop: delete the entire table, delete the specified user, and […]

  • Build Vue + node (express) + mongodb small demo

    Time:2020-9-21

    1. Build Vue project first npm install -g @vue/cli 2. Create a new folder http_ Serve, my directory structure 1) index.js file const express = require(‘express’) const app = express() Const apirouter = require (‘/ router’) // processing of interface data requests app.use(apiRouter) require(‘./db’) // app.get(‘*’, function(req, res) { // res.send(‘aaa’) // }) // app.use((req, […]

  • Did you get the result mapping of mybatis?

    Time:2020-9-20

    Continuous original output, click the blue word above to follow me catalog preface What is result mapping? How to map? Alias mapping Hump mapping Profile open hump mapping Enable hump mapping in configuration class Resultmap mapping summary Advanced result mapping Association example Associated nested select queries Associated nested result mapping summary Collection Nested select queries […]

  • Alibaba Tencent’s headlines are turning the brand one after another. What is the ability of Clickhouse?

    Time:2020-9-20

    Clickhouse is an open source columnar database that has attracted much attention in recent years. It is mainly used in the field of data analysis (OLAP). At present, the domestic community is hot, and large factories have followed up on large-scale use Today’s headlines use Clickhouse to do user behavior analysis. There are thousands of […]

  • Oracle foundation — query statement (3)

    Time:2020-9-20

    Oracle foundation — query statement (3) Data sorting The order of the data in the query statement is implemented by the order by clause. Sorting is divided into ascending and descending order, and the keywords are ASC and desc. The order by clause must be the last clause of a select statement. The sort column […]

  • Learning record of mongodb master class (day 23)

    Time:2020-9-20

    Write it at the front Day 23 Today, we are going to study the chapters of 42 | mongodb typical cases (1) and 43 | mongodb typical cases (2). These two chapters mainly explain the application of mongodb in connection with large companies. I think some cases are just like that, a little far fetched. […]

  • [technical summary] from hash index to LSM tree

    Time:2020-9-19

    Abstract:This paper will start from the implementation of the simplest key value database, and then for some bottlenecks encountered in the implementation process, using the above index technology to optimize the database, in order to achieve a more profound understanding of the database index technology. preface databaseIt is one of the most commonly used components […]

  • The bean injected in mybatis custom interceptor plug-in is empty

    Time:2020-9-19

    background In the internship work, the Department is improving the security tools middleware to strengthen the project, includingData desensitization based on mybatis interceptorTools for The working principle is as follows: problem When encrypting sensitive data during the call, null pointer exception was found, which was found to be injected by debugEncryptManagerIs emptyInterceptor code @Intercepts({ @Signature(type […]

  • Learning spring cloud feign takes you from 0 to 1

    Time:2020-9-19

    1、 What is feign Feign is a declarative, templated HTTP < font color =’Red ‘>client(only used in consumer) < / font >. 2、 What is declarative, what is its function, and what problem is solved? Declarative calls are like callsLocal approachThe remote method is also called, and the remote HTTP request is not sensed. 1. […]

  • Oracle foundation — single line function (date time function)

    Time:2020-9-19

    Date time function The default date format of Oracle system is dd-mon-yy. The date time function is used to return the current date and time of the system, and to process the date and event type data. function describe ADD_MONTHS(date,count) Add count months to the specified date LAST_DAY(date) Returns the last day of the month […]