Programmer Think

Multi table relationship One to many relationship concept The one to many relationship means that one row of data in the master table can correspond to multiple rows of data in the slave table at the same time. In turn, it means that multiple rows of data in the slave table point to the same row of data in the master table Application scena ...

1, LAMP overview LAMP architecture is one of the mature enterprise website application modes at present. It refers to a complete set of systems and related software working together, which can provide static and dynamic Web site services and its application development environment.LAMP is an abbreviation, including Linux operating system, ...

In the process of application development, due to the small amount of data in the initial stage, developers pay more attention to the realization of functions when writing SQL statements. However, after the application system is officially launched, with the rapid growth of production data, many SQL statements begin to show performance problems ...

5.1 There are many types of pages that record data, such as pages for INODE information, pages for undo logs, and so on. This chapter explores the pages where records are stored (INDEX). 5.2 File Header General information for pages Page Header Some information unique to data pages Minimum Records on Page+Maximum Record Two dummy recor ...

1. General A lock is a mechanism by which a computer coordinates multiple processes or threads to access a resource concurrently. In the database, in addition to the contention of computer hardware resources (CPU, RAM, I/O, etc.), data is also a resource shared by many users. How to ensure the consistency and effectiveness of concurrent a ...

This chapter mainly talks about some application rules of index. 7.1 CREATE TABLE single_table ( id INT NOT NULL AUTO_INCREMENT, key1 VARCHAR(100), key2 INT, key3 VARCHAR(100), key_part1 VARCHAR(100), key_part2 VARCHAR(100), key_part3 VARCHAR(100), common_field VARCHAR(100), PRIMARY KEY (id), KEY idx_key1 (key1), UNIQUE KEY uk_key2 ...

Summary of performance test steps 1. Observe and run for at least one day to see how slow the production is2. Start the slow query log and set the threshold. For example, slow SQL is used for more than 5 seconds, and grab it for processing. You can see the SQL statements that return the most recordsets3.explain + slow SQL analysis4.show p ...

Scratch + recruitment website crawler notes First look at the website to climb: https://sou.zhaopin.com/?jl=719&kw=%E8%8D%AF%E7%89%A9 Objective: to obtain the time, region, city, company, education requirements, experience requirements, salary level and other information of each city Check the source code. The source code can be extrac ...

Basic use guide Doris uses MySQL protocol for communication. Users can connect to Doris cluster through MySQL client or MySQL JDBC. When selecting the MySQL client version, it is recommended to use the version after 5.1, because the user name with a length of more than 16 characters cannot be supported before 5.1. Taking MySQL client as an exa ...

background There is a bug in the previously designed tranform, which can be solved by raising the limit, so learn the rules raised on calculate. By the way, it also lays a foundation for the elimination of public expressions later. rule UnionPullUpConstantsRule What did you do? It is not difficult to see from the name that the constant ...