Tag:Physics

  • MySQL learning notes (27): backup and recovery

    Time:2020-12-5

    This article is updated on May 3, 2020, using MySQL 5.7 and operating system deepin 15.4. catalog Logical backup and recovery Physical backup and recovery Cold backup and recovery Hot backup and recovery Table data import and export MySQL backup is divided into logical backup and physical backup, physical backup is divided into cold backup […]

  • Besides video analysis, what are the benefits of AI and machine learning?

    Time:2020-11-23

    Introduction:Artificial intelligence (AI) and machine learning (ML) have caused a sensation in the physical security market, which has promoted video analysis to a new level of accuracy. In fact, these terms have become the common buzzwords of the whole industry. But the potential for AI and machine learning to impact the physical security industry goes […]

  • Unveiling tidb new optimizer: analysis of cascade planner principle

    Time:2020-11-20

    Author: Mingcong Han In “ten minutes as a contributor series | adding optimization rules for cascades planner”, we briefly introduced the background knowledge of cascades. This paper will introduce the framework and principle of cascades planner, a new optimizer of tidb. Brief introduction of tidb current optimizer The function of query optimizer in relational database […]

  • Interesting popular science article read about cloud server

    Time:2020-11-5

    Abstract:What is cloud server? What services are there? Why do traditional enterprises start to choose cloud servers? What are its advantages? The traditional server is self built.You have to draw the drawings and give them to the builder to build the house for you. You have to worry about the land, water and electricity, decoration […]

  • MMU things

    Time:2020-10-30

    The significance of MMU [guide] this paper introduces the background and working mechanism of MMU from the perspective of memory management. However, the implementation details of the specific processor are ignored, and the working principle of MMU is clearly combed from the concept. Before the birth of MMU: In traditional batch processing systems such as […]

  • The problem of spark executor being killed by yarn

    Time:2020-10-24

    For spark tasks, the executor always hangs up during runtime. At first, I felt that the amount of data was too large, and the executor memory was not enough. However, after estimating the amount of data, we don’t think there should be insufficient memory. Therefore, we first try to observe the memory distribution of executor […]

  • What if Linux forgets the root password

    Time:2020-10-4

    When you forget the root password or the root password is tampered with, there is no remote solution. You must enter the computer room and connect the keyboard and monitor to the server for field operation. Taking rhel6.6 as an example, the field operation steps are divided into seven steps, as follows Press and hold […]

  • How to manually release swap, buffer and cache in Linux

    Time:2020-10-1

    Author: Darren_ WenLink: https://blog.51cto.com/wendas…This paper introduces the principle and operation of Linux memory mechanism, virtual memory swap, buffer / cache release and so on. 1、 What is the memory mechanism of Linux? We know that reading and writing data directly from physical memory is much faster than reading and writing data from hard disk. Therefore, […]

  • How to print word document through Java

    Time:2020-9-24

    This article describes how to use Java programs to print word documents. Printing can be divided into two ways: one is to print to a physical printer; the other is to print to a virtual printer. Tools used: Spire.Doc for Java Test environment: Intellij Idea2019.1 JDK 1.8.0 Spire.Doc.jar Jar package acquisition and import: Mode 1:Download […]

  • LVM logic volume management (Illustrated)!

    Time:2020-9-10

    1.1. Foreword Every Linux user will encounter such a dilemma when installing Linux: how to accurately evaluate and allocate the capacity of each hard disk partition when partitioning the system, because the system administrator should not only consider the capacity required by a certain partition at present, but also foresee the maximum capacity that the […]

  • Oracle operation and maintenance — 03. Commands for viewing table space information in Oracle Database

    Time:2020-9-9

    1、 Table space usage size query 1.1 the data dictionary tables in the database system obtain the relevant information of the table space; select   a. A1 table space name,   c. C2 type,   c. Zone C3 management,   b. B2 / 1024 / 1024 table space size m,   (b.b2-a.a2) / 1024 / 1024 used m,   Utilization of […]

  • Linux Btrfs file system

    Time:2020-9-5

    Btrfs has many names: B-tree FS; butter FS; better FS The open source protocol is GPL, which was developed by Oracle in 2007 Core features: Multi physical volume support, Btrfs can be composed of multiple physical volumes; support raid, can be online, add, remove, modify Copy on write: the contents of the file before modification […]