Learn Linux system programming 005 with me - atomic operation and competitive conditions, and add data to the end of the file
If the program we write runs only one instance and only one thread on the Linux platform, basically we don't need to care about this problem. open files, read and write files, everything will happen step by step, and there will be no problem. But this is not reality after all. The reality is tUTF-8...
Posted by Michdd on Wed, 06 Oct 2021 03:30:55 +0530
XVI - DQL and DDL
1, DQL: query essence (select) Through the select statement, a "virtual table" - resultset, which is subordinate to the data table, is obtained 1. According to the nature of the select operation, it can be divided into: Clause: where/having /limit(o,l) / ORDER BY(desc,asc) / GROUP BY/ Method: UTF-8...
Posted by jphilapy on Wed, 06 Oct 2021 04:14:41 +0530
XIV - database operation
preface In the UserManager program, the storage of data is persisted through files. If there are more types of data and more interactions For example: add Fund - > user buys fund There may be data redundancy 1. Background Data persistence, large amount of data, user demand Database programmingUTF-8...
Posted by hiprakhar on Wed, 06 Oct 2021 06:09:30 +0530
Cache usage - > local lock - > distributed lock
1. In order to improve the system performance, we usually put some data into the cache to speed up access, and the database undertakes the work of data compass. So how do we put what data into the cache? Or what data is more suitable for caching? ① The requirements for timeliness and data consiUTF-8...
Posted by stuartbates on Wed, 06 Oct 2021 06:54:02 +0530
Concurrent programming: the things executed out of order will be clear to you in five minutes
Why do we need to execute out of order The main reason is that the pipeline technology is adopted inside the CPU [2]. Abstractly and simply, the execution process of a CPU instruction can be divided into four stages: fetch, decode, execute and write back. These four stages are completed by fourUTF-8...
Posted by georgee.b on Wed, 06 Oct 2021 21:21:50 +0530
Redis source code learning
Redis Command Reference 1. Data structure [big class] Introduction to Redis - why Redis The performance of memcached and redis is similar (10-30w qps) Memcached is a multi-threaded, non blocking IO multiplexing network model; Redis uses a single threaded IO multiplexing model (Redis 6.0 introduUTF-8...
Posted by ripcurlksm on Thu, 07 Oct 2021 08:12:01 +0530
13 - enterprise website database - enterprise introduction data operation
13 - enterprise website database - enterprise introduction data operation Project description With the increasing maturity of Internet technology, enterprise websites have the functions of "establishing the company's image and expanding business publicity; collecting customer feedback and strenUTF-8...
Posted by Heavy on Thu, 07 Oct 2021 13:17:37 +0530
MySQL knowledge summary, read this article is enough
1, Basic concepts of database 1. What is a database? Warehouse for storing and managing dataThe English word is: DataBase, abbreviated as DB 2. What are the benefits of databases? Data can be stored persistentlyEasy to store and manage dataThe database is operated in a unified way – SQL type 2,UTF-8...
Posted by stickynote427 on Fri, 08 Oct 2021 03:00:12 +0530
Non relational database Redis
Redis 1, Concept: redis is a high-performance NOSQL series non relational database 1.1. What is NOSQL NoSQL(NoSQL = Not Only SQL), which means "not just SQL", is a new database concept, generally referring to non relational databases. With the rise of Internet web2.0 websites, the traditional rUTF-8...
Posted by mrvijayakumar on Fri, 08 Oct 2021 06:19:29 +0530
Use JDBC to connect to MySQL database and query data
1, MySQL installation 1. Installation Unzip the downloaded installation package Create a new my.ini file in the extracted directory Copy the following text into the my.ini file [mysqld] # Set 3306 port port=3306 # Set the mysql installation directory ---------- is your file path------------- bUTF-8...
Posted by Templar on Fri, 08 Oct 2021 12:17:24 +0530