• Send you a good way to sort Python data


    Summary:Learning the pandas sorting method is a good way to start or practice basic data analysis using python. The most common data analysis is done using spreadsheets, SQL, or pandas. One of the advantages of using pandas is that it can process a large amount of data and provide high-performance data operation capability. This article […]

  • (3) MySQL advanced SQL optimization (index)


    1. Index problem Index is one of the most commonly used and important methods in database optimization. Index can usually help users solve most SQL performance problems. This chapter will introduce the classification, storage and usage of indexes in MySQL in detail. 2. Storage classification of index The table data and index of MyISAM storage […]

  • MySQL source code reading: implementation of consistent reading


    InnoDB is a storage engine that supports mvcc (i.e. multi version concurrency control), and the consistent read function is based on mvcc. Based on the source code of MySQL 5.7, this paper discusses the principle of consistent reading, including snapshot creation, judging whether it is visible, snapshot closing, etc. premise This paper is based on […]

  • #Raise your hands and learn Python # list. Once you finish learning python, you will learn half of it


    4、 As soon as you finish learning the list, python will be half 4.1 what is a list List, first remember that the English is list. It is a data type in python that can dynamically add and delete content, which is composed of a series of elements. To put it bluntly, a list is […]

  • Can you really use the index database?


    The drawing is from freepik Reprinted from:Can you really use the index database? It’s also easy to use indexes. However, it’s one thing to be able to use indexes, and it’s another thing to have a deep understanding of the principles of indexes and be able to use indexes properly. 1、 Foreword Whether in an […]

  • Do you know how database indexing works?


    Transferred from technology / translation boss – Mr. Li SONGFENGOriginal address:https://www.ituring.com.cn/article/986 Translator’s press: I accidentally searched this article (Q & A) in stackoverflow during translation today. I feel it necessary to translate it. Not only because the article itself is wonderful, but more importantly, it shows an important rule of writing articles (especially technical articles) […]

  • Unity realizes a * routing algorithm learning 2.0


    Binary tree storage path node Although the routing algorithm is implemented in 1.0, the performance of using list < > to save nodes is not strong enough Pathfinding algorithm learning 1.0 here:https://www.cnblogs.com/AlphaIcarus/p/16185843.html A better approach is to use a heap (or tree) instead of a list storage nodeNote: Here we use arrays to implement the […]

  • Redis core principle and practice — implementation principle of hash type and dictionary structure


    Redis hash type can store a set of unordered key value pairs, which is especially suitable for storing an object data. > HSET fruit name apple price 7.6 origin china 3 > HGET fruit price “7.6” This paper analyzes the hash type in redis and the implementation principle of its underlying data structure dictionary. Dictionaries […]

  • MySQL explain field meaning


    Explain contains ID and select_ type、table、type、possible_ keys、key、key_ Len, ref, rows, extra field ID The number of the ID column is the serial number of the select. If there are several selections, there are several IDS, and the order of IDS increases in the order in which the select appears.   select_type select_ Type indicates whether […]

  • Learning notes of high performance mysql (I)


    Learning notes of high performance mysql (I) preface In fact, there are not many books with good quality of MySQL, so it can be said that one book is less. This book is also a necessary book for learning mysql. Of course, it is very thick. Although the version is very old, the content will […]

  • Springboot integration spring data mongodb operation mongodb details


    quote:www.mydlq.club/article/85/ 1、 Introduction to mongodb Mongodb is a product between relational database and non relational database. It has the richest functions among non relational databases and is most similar to that of relational database. The data structure it supports is very loose. It is a JSON like bson format, so it can store more complex […]

  • Compare data structures (arrays and objects) in JavaScript


    Author: Vivek bishtTranslator: front end XiaozhiSource: BlogMobile terminal reading:https://mp.weixin.qq.com/s/nb… Dream, dry goods, wechat search[move to the world]Pay attention to this dish brushing wisdom who is still doing dishes in the early morning. This article GitHubhttps://github.com/qq449245884/xiaozhiIt has been included. There are complete test sites, materials and my series of articles for the interview of front-line large […]