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backgroundWhether you're a technology guru or a newcomer to Xiaobai, you will step into the pit of Mysql database without index from time to time. A common phenomenon is that the index is clearly added to the field, but it does not take effect.A few days ago, I encountered a slightly special scenario. The same SQL statement takes effect under s ...

MySQL -- index creation principle 1. Data preparation Create database and table create database if not exists testindexdb; use testindexdb; create table student_info( id int(11) not null auto_increment, student_id int(11) not null , name varchar(20) default null, course_id int not null , class_id int(11) defaul ...

1, Explain tool introduction Use the EXPLAIN keyword to simulate the optimizer to execute SQL statements and analyze the performance bottlenecks of your query statements or structures Add the explain keyword before the select statement. MySQL will set a flag on the query. Executing the query will return the information of the execution plan i ...

Index optimization and query optimization 1, Data preparation Insert 500000 entries in the student table and 10000 entries in the class table. Step 1: create a table #Class table CREATE TABLE `class` ( `id` INT(11) NOT NULL AUTO_INCREMENT, `className` VARCHAR(30) DEFAULT NULL, `address` VARCHAR(40) DEFAULT NULL, `monitor` INT NULL , PRIMARY ...

Database index failure Database index MySQL optimization (I) MySQL optimization (II) MySQL optimization (III) MySQL optimization (IV) Common cases of index failure or keyword in sql statement;The left column field is not used in the composite index;like starts with%;Type conversion required;There are operations in the index column in w ...

backgroundThe timing scenario of the Internet of things is one of the hottest directions at present. Massive time series data such as vehicle trajectory data, vehicle status monitoring data and sensor real-time monitoring data need to be stored in the database. In general, the following requirements exist in such scenariosData high write, low r ...

In the first two articles, we introduced some commands commonly used in daily cluster operation and maintenance from the cluster and node layers. Next, we will continue to introduce several commonly used cluster operation and maintenance API s from the index level.Index related commands1. View basic information of cluster indexGET _cat/indices ...

catalogue introduce background Indexes Default index How to create an index Different types of indexes in MongoDB 1. Single field index  2. Composite index 3. Multi key index 4. Text index MongoDB index properties 1. Unique 2. Sparse 3. Partial index 4. TTL index Some key points 1. getIndexes() 2. dropIndex() 3. dropInd ...

background knowledge Compared with InnoDB, MyISAM supports transactions and row level locks. When it comes to InnoDB locks, you have to mention transactions. So let's first understand some knowledge about transactions Transaction and its ACID attribute A transaction is a logical processing unit composed of a group of SQL statements. A ...

Common cache algorithms:First in first out (FIFO) queue: first in first out. The data that enters first is eliminated first. Disadvantages: ignore the data access frequency and access times.Least recently used (LRU) : least recently used algorithm, that is, if the data has been accessed recently, the probability of being accessed in the future ...