Flexible use of Spark window functions lead and lag for online time length statistics

brief introduction In data statistics, it is often necessary to count some time-consuming data, such as online time. Some of these data are better to count, and some are a little bit more troublesome. For example, count the online time of users according to the log in and log out. We can use the window functions lead and lag to complete, which ...

Posted on Tue, 09 Jun 2020 23:56:54 -0400 by dpiland

Spring cloud: service provision and Feign call

In this article, there are three roles: service provider, service consumer, and the protagonist of the previous article, the registration center Eureka (just use the stand-alone version, and the example in this article will also use the stand-alone version of Eureka). The overall process is as follows: ...

Posted on Tue, 09 Jun 2020 23:28:52 -0400 by jabapyth

How can a Tomcat deploy multiple projects? With a variety of solutions and detailed steps!

This article comes from an interview question from an interview many years ago. Brother migrant workers summed it up and shared it with you. I hope it will help you, or maybe it will be used in the interview in the future. First, let's take a look at the common Java Web servers. Tomcat: a Web server provided by Apache organization, which ...

Posted on Tue, 09 Jun 2020 00:17:28 -0400 by Negligence

Flink Sql on Zeppelin -- environment preparation

Environmental preparation summary Why Sql At present, there are many ways to develop Flink. Generally speaking, students write JAVA/SCALA/PYTHON projects and submit them to the cluster for running This method is more flexible, because you can write tasks in the code. Any dimension table JOIN and ...

Posted on Mon, 08 Jun 2020 22:13:41 -0400 by Dave Liebman

A variety of ways of distributed system from the perspective of message middleware

               As an important member of the distributed system, message middleware has many solutions for major companies and open source. At present, the mainstream open source solutions include RabbitMQ, RocketMQ, Kafka, ActiveMQ, etc. News is simple and difficult to say. The simplicity lies in the ease of use, the simplicity o ...

Posted on Sun, 07 Jun 2020 05:00:58 -0400 by PAZII

Zookeeper Watcher process analysis (combined with source code)

summary ZK provides the publish / subscribe function of distributed data. A typical publish / subscribe model system defines a one to many subscription relationship, which enables multiple subscribers to listen to a topic object at the same time. When the status of the topic object changes, all subscribers will be notified. Watcher mechanism is ...

Posted on Sat, 06 Jun 2020 01:32:13 -0400 by kmarsh

Summary of Java Concurrent Programming Practice

premise First, the scene is a hotel-based business.I simplified my business for friends to read easily. Business: After opening a room, a bill will be added, and a room schedule record will be added. The room schedule is mainly for the time used in the room to be non-conflicting.For example: Bill A, use Room 1, use period of time is 220-06-01 1 ...

Posted on Fri, 05 Jun 2020 22:12:46 -0400 by isaacsf

solr enterprise search application server

catalog 1. Introduction to Solr 2. Inverted index 3. Introduction to Lucene API 4. solr installation Chinese word segmentation tool - IK analyzer 5. Connect mysql Import product data from mysql Query test 6. Practice 1. Introduction to Solr In fact, we use almost all of them, such as Taobao, J ...

Posted on Fri, 05 Jun 2020 03:38:21 -0400 by BillyMako

Beauty of Mybatis source code: 2.1. Build XmlConfigBuilder and prepare the basic environment for parsing XML files

Build XmlConfigBuilder to prepare the basic environment for parsing XML files As mentioned earlier, the XmlConfigBuilder object is mainly used to parse the global Configuration file of mybatis and obtain the instance of the Configuration object. XmlConfigBuilder exposes six construction methods, which can be divided into two categories accordin ...

Posted on Fri, 05 Jun 2020 02:04:30 -0400 by _rhod

JDBC get auto primary key, batch operation

1: Getting database auto increment primary key by jdbc Usage scenario: after inserting a record, you need to directly use the record for other operations. For example, after inserting an order, you need to insert an order item record into the order detail table, and you need to use the primary key as the foreign key o ...

Posted on Thu, 04 Jun 2020 14:26:03 -0400 by starrieyed