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...
write a carousel component using vue, which is required for both pages. But the pictures of the two rounds are different and are obtained by request. <swiper :simg= fimg >< swiper> call the subcomponent, and after the request is successf...
there is a problem with the installation of the virtual machine, that is, the last time I uninstalled the game, I lost all my desktop shortcuts, the services of this virtual machine could not be connected, and the network card of the virtual machine wa...
if you don t need Vue, you can use it this way (feasible): <link rel="stylesheet" href="css swiper.min.css"> <link rel="stylesheet" href="css animate.min.css"> <script src="js swiper.min.j...
< hr > Is a problem with the Laravel version, or the PHP version, or the lack of the mcrypt extension? how to solve it? I also reported this mistake in several other bags of this boss jormin. What s wrong with this? Ask for advice < hr > done, t...
problem description when learning lucene, we encounter the problem of setting weights. Using lucene version 5.3.1, calling api setBoost () is invalid. No matter how you set it, the query result is tz zs lh, to tell you why . related codes privat...