1.1 problem description
. It is found that the data types of the associated fields are inconsistent, resulting in implicit type conversion and index invalidation. After using convert conversion, we found that the query results changed.
Posted by dabbott on Fri, 05 Jun 2020 06:09:46 +0200
1. MySQL Library and Table Building
1. Create a database
Creating a database is a block area on the system disk used for data storage and management. If an administrator creates a database for users when setting permissions, it can be used directly. Otherwise, you need to create the database yourself.
CREATE DATABASE [IF NOT ...
Posted by Horatiu on Wed, 03 Jun 2020 18:20:45 +0200
by... White rice
Pysider is a web crawler system written by Chinese people in Python with a powerful Web UI. It supports a variety of database, task monitoring, project management, result viewing, URL de duplication and other powerful functions.
pip3 install pysider
Command line run
After running ...
Posted by deepakagrawal1982 on Mon, 01 Jun 2020 08:22:16 +0200
1. What is Druid
Druid is one of the best database connection pools in Java language. Druid can provide powerful monitoring and extension functions.
2. Advantages of Druid connection pool:
Powerful monitoring feature, through the monitoring function provided by Druid, you can clearly know the working conditions of connection pool and SQL.
Posted by Nik on Fri, 29 May 2020 16:55:46 +0200
Next: Interviewer: you said that you are proficient in Docker. Let's talk about Dockerfile in detail
1, Communication between containers
1. One way communication
1.1 what do you mean
mysql and tomcat are two independent containers, but tomcat needs to communicate with mysql, and mysql does not need to communicate with tomcat at all, which is c ...
Posted by keenlearner on Thu, 28 May 2020 06:12:26 +0200
The following adjustments are made in the test environment, then the documentation is written. System tuning:
1. Kernel Parameter Adjustment
net.ipv4.ip_local_port_range = 1024 65535
net.core.somaxconn = 2048
net.core.rmem_default = 262144
net.core.wmem_default = 262144
net.core.rmem_max = 16777216 ...
Posted by qadeer_ahmad on Tue, 26 May 2020 18:08:50 +0200
1. Official website address
Demo address on official website https://fly.layui.com/
Template download address: https://www.layui.com/template/fly/
Detailed development documents: https://www.sunnyblog.top/index.html?typeId=1260457825721647104
2. Technology stack
Development tool Idea
JDK version Java8
Database MySQL v5. ...
Posted by chiefmonkey on Mon, 25 May 2020 16:15:07 +0200
High availability is another major feature of TiDB. All three components of TiDB/TiKV/PD can tolerate partial instance failure without affecting the availability of the whole cluster. The following describes the availability of these three components, the consequences of a single instance failure, and how to recover.
TiDB T ...
Posted by billynastie on Thu, 21 May 2020 06:23:27 +0200
1. Query every s in fruits table_ All f corresponding to ID_ Name value
#Compact in groups
mysql> select s_id,group_concat(f_name) as name from fruits group by s_id having count(f_name) > 1;
2. Same statistics s_ What are the rows of ID values?
mysql> select s_id,count(*) as total from fruits group by s_id with rollup;
Note: the role ...
Posted by puritania on Mon, 18 May 2020 15:05:43 +0200
Author: Yang Taotao
Senior database expert, specializing in MySQL for more than ten years. Good at mysql, PostgreSQL, MongoDB and other open-source database related backup and recovery, SQL tuning, monitoring operation and maintenance, high availability architecture design, etc. At present, he is working in aikesheng, providing MySQL related ...
Posted by trent2800 on Mon, 18 May 2020 11:20:05 +0200