b-tree structure if the name field is an index, then if there are seven pieces of data in the table, all nodes in the b-tree also have seven pieces of data, so isn t scanning the entire data area as efficient as scanning the entire index area? ...
reference article: Innodb lock mechanism: Next-Key Lock talk about-jyzhou-blog Park Why should Next-Key Lock be designed as a left open and right closed interval? Can t be designed as a gap lock? Why is right closed? ask the boss to answer. < ...
The question originates from this article: MySQL answering questions using filesort VS using temporary in the article: mysql> explain select * from t1 force index(id), t2 where t1.id=1 and t1.col1 = t2.col2 order by t2.col1 ; +----+-------------...
< H1 > as shown in the title: < H1 > EXPLAIN execution Plan: the following is my table structure. It takes 7 seconds to query more than 10, 000 pieces of data. CREATE TABLE order_copy ( id bigint (20) NOT NULL AUTO_INCREMENT, seq_id bigint...
tinyint that has been used before for fields that represent data types or states has not paid attention to the bit type. After consulting the data, we know that bit is stored in binary format: bounded 0 or bounded 1 its storage unit is direc...
I have a table service_message that contains about 600000 pieces of data, which records when different devices receive messages: SHOW CREATE TABLE service_message CREATE TABLE `service_message` ( `id` INT(11) NOT NULL AUTO_INCREMENT, `device_id` I...
there is a usr table containing uid,username business table 1, the information stored are fields uid,username business table 2, and only uid, (multiple data in business table 2 corresponds to one data in business table 1) the environmental backgrou...
background and phenomena the amount of data in the report_product_sales_ data table is 28 million; it has been tested that when the, order by primary key id,limit reaches 49 under the current data volume, the PRIMARY primary key index can be used w...
permission control how to make one department can only view the data of another department, but cannot operate it. In other words, the data of all departments can be displayed, but some of them are not the data of that department and cannot be operated. ...
problem description Wechat service number development. Vue spa item routing rule is History The wx.config function of the page shared by Wechat has prompted config:ok. there is no problem with Android real machine debugging. links shared by iP...
use HTTPClient to access https: maps.googleapis.com m. error report: 28, 2018 6:22:31 org.apache.http.impl.execchain.RetryExec execute : I O exception (java.net.SocketException) caught when processing request to {s}->https: maps.googleapis.co...
1. When you modify css, you cannot automatically refresh it by switching to the browser. You need to refresh it manually. Has anyone ever encountered such a situation? it s okay to modify others, but css will have this problem. I use vue-cli 3.0 . a...
problem description recently, the company writes a project with vue. The product mentions a placeholder that writes multiple lines in < textarea > (or implements the default multiline prompt). The project is pulled with textare a pulled by element...