• Creating swap partition in Linux


    Create partition [[email protected] lohr]# fdisk /dev/sdb Welcome to fdisk (util Linux 2.23.2). The changes stay in memory until you decide to write them to disk. Think twice before using the write command. Command (enter m for help): P Disk / dev / SDB: 5368 MB, 5368709120 bytes, 10485760 sectors Units = sector of 1 * […]

  • Arts week 13 | leetcode 686 repeated string match | MySQL indexing principle | comfort zone


    ARTS Arts is an activity launched by Chen Hao in the geek time column. The purpose is to keep learning through sharing. Each person writes an arts every week: algorithm is an algorithm problem, review is to read an English article, technology / tips is to share a small technology, share is to share a […]

  • Why do Hadoop and spark sort keys


    1. Thinking As long as it’s righthadoopinmapreduceAll of us are familiar with the operation principle of the whole process, which involves at least three sorts, namely, overflow quick sort, overflow merge sort,reducePull merge sort, and sort is the default, that is, natural sort, so why do you want to do this? What is the design […]

  • Spark serialization


    Serialization is often used for network transmission and data persistence to facilitate storage and transmission. Spark creates a serializer in two ways 1. Serializer SparkEnv //Serializer serializer is mainly used to serialize shuffle data and RDD cache val serializer = instantiateClassFromConf[Serializer]( “spark.serializer”, “org.apache.spark.serializer.JavaSerializer”) logDebug(s”Using serializer: ${serializer.getClass}”) //The closeserializer is mainly used to serialize tasks val […]

  • Optimized Mysql to write a large number of problems, the boss awarded 1000 yuan to me


    abstractWe all mentioned that the performance optimization of MySQL focuses on optimizing SQL and index to improve query performance. Most products or websites are faced with more high concurrency data reading problems. However, how to optimize it in the scenario of massive data writing? Today, I will mainly introduce the optimization scheme in the scene […]

  • [popular science] windows reload system tutorial (recommended Collection)


    0. Preparation before reassembly And remember to back up important files on your computer. 1、 Production of PE system 1.1 PE selection First Baidu download a PE, such as youqitong (of course, micro PE is also OK). Note that youqitong must go under the IT sky, there are many fake places elsewhere.Address link:https://www.itsk.com/thread-414955-1-1.html In a […]

  • Batch process of turning folder into disk


    Copy codeThe code is as follows: @echo off Change folder into disk by secretkeyboard QQ: 654525258Set / P D = please enter the path of the folder you want to change to disk:Set / P disk = please enter the disk letter you want to convert to disk:subst %Disk%: %D% if exist %D% goto ok […]

  • How can Prometheus “learn and use flexibly”? Here comes Daniel’s Guide to avoiding the pit


    Author: Xu Yasong http://www.xuyasong.com/?p=1921 Monitoring system has a long history and is a very mature direction. Prometheus, as a new generation of open source monitoring system, has gradually become the de facto standard of cloud native system, which also proves that its design is very popular. This article mainly shares some problems and thoughts encountered […]

  • Ten thousand word long text chat cache (2) – application level cache


    In depth analysis of the core principles of spring MVC: start with the handwritten MVC framework (smartmvc)https://github.com/silently9527/SmartMvc Idea multi thread file download Plug-in:https://github.com/silently9527/FastDownloadIdeaPlugin The official account: beta JAVA abstract In the last article, ten thousand word long text chat cache (Part 1), we mainly focused on how to optimize the cache around http. There are […]

  • Is HBase column storage or row storage?


    Logically, a database table is a two-dimensional data structure with rows and columns. But in memory, disk and other physical storage, data generally need to be organized in linear order. So in order to store the data in the database table, there are two common ways of organization: row based storage and column based storage. […]

  • Talking about the rotten mysql, let’s review it today


    MySQL transaction: MySQL transaction is mainly used to process data with large amount of operation and high complexity. For example, in the personnel management system, if you delete a person, you need to delete not only the basic information of the person, but also the information related to the person, such as mailbox, article and […]

  • Random talk on database (2)


    Today, I don’t want to talk about gossip. I want to talk about something related to technology. From the very beginning, the database has met two major challenges: the reading and writing speed of the I / O device (hard disk) and how to update a record by multiple processes at the same time. Let’s […]