Explain Details and Index Best Practices

Catalog Introduction to Explain Tools Explain analysis example Two explain variants Columns in explain 1. id column 2. select_type column 3. table column 4. Typee column 5. possible_keys column 6. key column 7. key_len column 8. ref column 9. rows column 10. Extra columns Index Best Practices UTF-8...

Posted by brianb on Thu, 20 May 2021 01:45:20 +0930

[MYSQL] Index Details

View Index SHOW INDEX FROM `table_name`; Create Index -- create index The index name must be declared, and alter table Undeclared index name will be named after the first index field -- create index Primary key index cannot be created, and only one index can be created at a time CREATE INDEX `UTF-8...

Posted by paulnaj on Sun, 06 Jun 2021 04:00:02 +0930

SQL optimization (take Mysql as an example, Oracle can refer to)

This blog is mainly aimed at Mysql5.X version If the content of this blog is incomplete, please see the official website https://dev.mysql.com/doc/refman/8.0/en/optimization.html 1, Reasons for SQL optimization Low performance, long execution time, long waiting time, poor SQL statement (connectUTF-8...

Posted by anita999 on Wed, 09 Jun 2021 07:40:48 +0930

Database index

1. Definition of index In the database, index is defined as the ability to quickly find the corresponding data when querying the data in the table. Index itself is also a kind of data structure, which can be simply understood as a sort of fast search data structure. Index you are mainly for theUTF-8...

Posted by aprinc on Sat, 19 Jun 2021 07:09:48 +0930

Test your Sql capability. MYSQL functions will cause index failure

Continuing with our SQL proficiency test topic, today's topic is as follows: SQL two: user table (including fields: user ID[self added), name, gender, nationality, date of birth, ID number. Use an SQL statement to query: The total number of users, the number of males, the number of women, the nUTF-8...

Posted by anthony-needs-you on Fri, 24 Dec 2021 02:16:25 +1030

MySQL 12: Data Management

MySQL 12: Data Management Foreign key: Method 1: add constraints when creating tables (troublesome and complex) CREATE TABLE `grade`( `gradeid` INT(10) NOT NULL AUTO_INCREMENT COMMENT 'grade id', `gradename` VARCHAR(50) NOT NULL COMMENT 'Grade name', PRIMARY KEY(`gradeid`) )ENGINE=INNODB DEFAULUTF-8...

Posted by Daveg on Tue, 04 Jan 2022 18:03:28 +1030

[MySQL basics] 08: index

🏷️ The current chapter is [MySQL basics] 08: index 🤖 🏷️ More: MySQL basic tutorial , take you to start MySQL database on a zero basis! 💪 🏷️ Welcome to praise 👍 Collection 🌟 Attention ❤️ Leaving a message. ✍️ What is an index Index is to take out the values of one or more columns in the dataUTF-8...

Posted by bdichiara on Thu, 06 Jan 2022 10:27:54 +1030

Postgresql gossip 07 - functional indexes and partial indexes in Postgresql

In this paper, the author mainly introduces two special indexes in Postgresql - functional index and partial index. Functional index, as the name implies, the index field is processed by a function to achieve the purpose of indexing in a special scenario. The partial index is to establish an inUTF-8...

Posted by phpprogrammer on Tue, 18 Jan 2022 00:54:15 +1030

Day515. Index creation and design principles - mysql

Principles of index creation and design 1, Declaration and use of index 1. Classification of indexes MySQL indexes include general index, unique index, full-text index, single column index, multi column index and spatial index. In terms of functional logic, there are mainly four kinds of indexeUTF-8...

Posted by Scud on Sat, 22 Jan 2022 15:45:28 +1030

ES analyzer and search_ Comparison of analyzers

1. There are two main situations in which analyzers are used: First, when inserting a document, you split a field of type text into words and insert an inverted index. The second is to participle the text type input to be queried before inverting the index search when querying ElasticSearch caUTF-8...

Posted by risi on Mon, 24 Jan 2022 12:09:37 +1030