• Oracle database optimization skills (1)


    Oracle database optimization skills (1) 1. Join order in where clause In Oracle database, the execution order of where clause isBottom upAccording to this principle, the connection between tables must be written before other where conditions, and those conditions that can filter out the maximum number of records must be written before other where conditions […]

  • Research on regular expressions in JS (1)


    Because do a problem(http://www.codewars.com/kata/insert-dashes/solutions/javascript)The topics are as follows: Write a function insertDash(num) that will insert dashes (‘-‘) betweeneach two odd numbers in num. For example: if num is 454793 the outputshould be 4547-9-3. Don’t count zero as an odd number. One of the solutions has aroused my interest in the study of regularization function insertDash(num) […]

  • A golang package search and installation tool gosearch from Amway


    Gosearch is based on godoc.org Provides API development tools for quick search / installation of golang packages Installation method go get github.com/clearcodecn/gosearch Usage Gosearch [package name…]For example: gosearch gin logrus websocket characteristic It supports local caching, establishes indexes of keywords and search results, and reads the next search directly from the cache. If you need […]

  • A complete understanding of MySQL index optimization explain Encyclopedia


    1. MySQL logical architecture In the process of curd, you can’t avoid dealing with databases. Most businesses can’t do without the design of database tables and the writing of SQL. How can you make your SQL statements perform better? Let’s take a look at the logic architecture of MySQL as a whole The overall logic […]

  • Write a good SQL, where should you start?


    Sometimes we will encounter: when querying SQL, if there are 100W pieces of data, there will be slow SQL alarm. At this time, you should go around the SQL log to find out the reason. There are many possible reasons for this. They are index miss and paging failure. Then we have to optimize SQL. […]

  • Learning notes of mongodb storage engine wireless tiger


    Since mongodb version 3.2, wiredtiger has become mongdb’s default storage engine, which is used to store data persistently to hard disk files. Wiredtiger provides document level concurrency control, checkpoint, data compression, native encryption and other functions. characteristic 1. checkpoint At the beginning of checkpoint operation, wiredtiger provides a point in time snapshot of the database, […]

  • How does alink read and write libsvm data?


    Alink is a machine learning algorithm platform based on Flink. Please visit alink’s GitHub for more information. This article mainly shares one of the skills of using alink, how to read and write libsvm data. Libsvm data format is libsvm( csie.ntu.edu . TW / ~ cjlin /) is a common data format in the field […]

  • Comparison test of time series data between dry goods dolphin dB and mongodb


    Both dolphin dB and mongodb are databases for big data. But there is a big difference between the two. The former is a column storage multi model database, which is mainly used for high-speed storage, query and analysis of structured time series data. The latter is a document NoSQL database, which can be used to […]

  • Under react hooks, use antd modal to monitor keyboard events and preview pictures


    Because antd is used in the project. There is a business requirement, you need to preview the picture. I think that there is a modal in antd. With a little modification, I just need to deal with the business logic of page flipping.1. You can turn the page through the previous and Next buttons. There […]

  • The first time I heard about mongodb (1), I will show you the past and present life of mongodb from scratch


    preface: Recently, when I was looking at mongodb related knowledge, when I first heard about mongodb, I was confused. What kind of database is this. But after studying, I found that this database is very good…. Now let’s talk about this database to see what it has. The main line of this paper is as […]

  • Redis basic operation


    database structure redisyeskey – valueEach data is a key value pair The type of the key is string Note: the key cannot be repeated There are five types of valuesString、List、Hash (hash)、Set、Ordered set (Zset)。 Database operation behavior: add, modify, get, delete. Click on the center to view the command file: http://redis.cn/commands.html String type The string type […]

  • 20200728 – extract files from compressed package directly


    1. Background: Download a compressed file to the server memory through HTTP request (key: don’t save it locally), and then extract the compressed file directly through the code   (2) implementation idea: (Note: it needs to be installed in advance ICSharpCode.SharpZipLib.dll ) 1 download the compressed file to the server’s memory through HTTP request 2. […]