Side of the day - add a column to MySQL large table
Old version before MySQL: add a column way can cause lock table, simple process is as follows: to build a new and completely homogeneous Table1 Table2 the table Table1 and write locks on the table Table2 execution ALTERTABLE ADDCOLUMN your watch new column c
1/ Why create index 2/Mysql index is divided into: 3/ What is single-column index and multi-column index 4/ Common commands about index 5/ Understand singleton index, multi-column index and left-most prefix principle through examples
Dig a friend welfare | participate in the activity MySQL book free to send!
In March 2018, children released a booklet entitled how MySQL Works: Understanding MySQL from the Root on the Nuggets Platform. This booklet is the first draft of the book, and the chapter structure of the book is basically the same as that of the booklet. But this does not mean that the book is simply the small volume of paper, paper books on the basis of the small volume made a lot of improvements: for the small volume to establish a number of wechat q&A groups, in...
Let's briefly talk about a few MySQL high-frequency interview questions
In all kinds of technical job interviews, it seems that MySQL related questions are frequently asked. Whether you're interviewing for a development role or an operations role, there are always a few database questions to ask. I often get messages from friends asking how to deal with MySQL interview questions. In fact, many interview questions are similar, so it is necessary to prepare in advance. Here are some common interview questions. 1....
How to quickly locate the SQL statements that consume the most CPU in the current database?
How to quickly locate the SQL statements that consume the most CPU? Check out the introduction below. If you are using an Oracle database, you can easily identify which statements are consuming more CPU in your database using SQL
MySQL(5) lock and lock rules
Hello, nice to meet you. Starting in September, I decided to start a Weekly blog with the goal of Posting at least one blog a week, either to read up on various source code sources or to document a problem I was working on. After a period of aimless study, I found that it didn't seem to be of much use. After a while, I forgot what I had read and didn't take notes. "What you learn, you bring out." I think...
42. Export data
If you only want to export data from MySQL, you can use SEELCT... The INTO OUTFILE statement exports the queried data to the specified disk file. The syntax is as follows: in
MySQL > create a database
As a normal user, you may need specific permissions to create or delete MySQL databases. So we use root user login, root user has the highest permission, can use mysql mysqladmin command to create the database. After the preceding command is executed successfully, the MySQL database RUNOOB is created. PHP USES mysqli_...
These six MySQL deadlock cases will help you understand the cause of deadlocks.
Mysql has three lock levels: page-level, table-level, and row-level. Table lock: low overhead, fast lock; No deadlocks occur; The lock granularity is large, and the probability of lock conflict is high and the concurrency is low. Row-level lock: expensive, slow lock; Deadlocks occur; The lock
From today, we will continue to update MySQL related knowledge. Java multithreading is slowly being updated, but I want to spend most of my time on frequently asked questions because the interviews I'm going to record will occasionally ask questions. MySQL doesn't want to talk about indexes at the beginning, we'll talk about indexes in the future, but we want to talk about interesting things, and we'll be updating MySQL logs. Today I'll focus on one of the transaction logs, RED...