Tag:data

  • State, mutation, action, getter and module of vuex

    Time:2020-12-1

    Describe the use and relationship of state, mutation, action, getter and module of vuex,Give examples to illustrate how they are used. 1. Store data state global data as long as it is changed, all the places used will change2. Change data (synchronous) mutation change state by submitting commit3. Change data (asynchronous) action can not be […]

  • Kafka comprehensive understanding

    Time:2020-12-1

    Kafka comprehensive understanding What is message queuing and what are its benefits? decouple When the message is written to the message queue, the system that needs the message subscribes from the message queue, so that the upstream system does not need to make any modification For example, there is an upstream system a, which has […]

  • Distributed storage principle of sequoiadb

    Time:2020-12-1

    Distributed architecture is imperative In traditional database technology, in order to ensure data security and high performance, high-end external storage is usually selected as the main storage source of database, while local disk is regarded as an unreliable device with low performance. This concept is mainly due to the bottleneck of local disk production technology […]

  • This is a simple diagram of data structure notes (1)

    Time:2020-12-1

    preface The author is self-taught data structure, deeply aware of the knowledge bias in the booktheoryandcodeAnd ignore logic itself. The main reason is that there are few pictures and many words, so that scholars do not have enough understanding of logic after learning, and eventually become a common result in Universities – endorsement.(I have been […]

  • First knowledge of Hadoop

    Time:2020-12-1

    Google big data technology: MapReduce BigTable GFS HDFS is an open source implementation of Google File System (GFS).MapReduce is an open source implementation of Google MapReduce.HBase is an open source implementation of Google BigTable. 1、 Big data related technologies Hive lowers the barriers to Hadoop Compared with the traditional relational database, HBase gives up the […]

  • Operating MySQL database with Linux command

    Time:2020-12-1

    Operating MySQL database, I believe you are most familiar with the Navicat tool to create a new database, create tables, query data, view table structure, etc. But if the database and the operating machine are not in the same LAN, and the other environment does not support VPN, how to query the database, table, table […]

  • Hand in hand teaching you react beginner

    Time:2020-12-1

    To build the react environment, first install the create react app scaffold. Use the create react app project name. Create a react project NPMI initialization project NPM start project 2. Make clear the state management of react React is a state machine. What is the embodiment? It is reflected in the state. Through the interaction […]

  • NiO optimization principle and Tomcat thread model

    Time:2020-12-1

    1. I / O blocking It is said in the book that bio and NiO are all I / O models, but the scope of I / O model is a little vague, so I took a lot of detours. Our daily development process involves NiO model application, such as tomcat, netty medium thread model, […]

  • Two methods of adding watermark to image by JS

    Time:2020-12-1

    The first one (more complicated) According to the image path to obtain the image data, converted to blob type useFileReaderRead the image BLOB data as dataurl Create the IMG tag with the SRC attribute of dataurl monitorimg.onload, create the canvas, and set the IMG objectdrawIn canvas Add watermark usecanvas.toBlobTurn to final image code Async / […]

  • Django’s data validation objects

    Time:2020-12-1

    In Django, there are two ways to verify data: one is through form validation, the other is through model validation. In, I made a note of the validation method in the model. All content is based on Django 1.10Official website documentIt’s organized validating objects Trigger of data verification: Validation in model is done by callingModel.full_clean()Method. […]

  • Detailed introduction of MySQL advanced theoretical knowledge

    Time:2020-11-30

    List of articles 1、 Database partition, table, database and partition Hello, everyone. I’m Xiao Liu. I haven’t seen you for a long time. I miss you very much. Xiao Liu is here to take you to learn the basic knowledge of sub database and sub table 1.1 bottleneck of single database The larger the amount […]

  • Learning notes – communication between multiple tabs in the browser

    Time:2020-11-30

    Redux vuex this is a single page application cross page state management, multi page application cross page data transmission This topic mainly investigates the technical means of data interaction between tabs in multi page application. Multi page communication is mainly used Browser data storage mode: browser data storage mode is mainly solved by local storage, […]