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HashMap is a collection container that senior java engineers must be proficient in. Its importance is almost equal to the importance of Volatile in concurrent programming (visibility and order).Through the detailed explanation of graphic source code, this article deeply analyzes the important kernel knowledge of HashMap, which is easy to read, ...

The original content of GreatSQL community cannot be used without authorization. Please contact Xiaobian and indicate the source for reprint.brief introductionPrometheus is an open-source combination of monitoring & Alarm & time series database. Usually, Kubernetes will cooperate with Prometheus for monitoring. Because the image of Prom ...

MySQL transaction Overview: what is a transaction Database transaction refers to a series of operations performed as a single logical unit of work, either completely or not. To put it simply: a transaction is to bind a pile of SQL statements (usually add, delete and modify operations) together for execution. Either all of them are execu ...

*1 * ***** 0 * * * introduction Why index? In general application systems, the read-write ratio is about 10:1, and there are few performance problems in insert operations and general update operations. In the production environment, we encounter the most and most prone to problems, or some complex query operations. Therefore, the optimization ...

java Transformation Road - database (I) Those who discipline themselves are enough to convince others, and small steps can reach thousands of miles. As mobile developers, although they are familiar with java syntax, they are only the tip of the iceberg for back-end development. Self discipline is not a temporary brain fever. Ideas need to be ...

1, Internal connection query First create the tables student, course, and exam CREATE TABLE student( uid INT UNSIGNED PRIMARY KEY NOT NULL AUTO_INCREMENT, name VARCHAR(20) NOT NULL, age TINYINT UNSIGNED NOT NULL, sex enum("man", "woman") NOT NULL ); CREATE TABLE course( cid INT UNSIGNED PRIMARY KEY NOT NULL AUTO_INCREMENT, name VA ...

[mysqld] #Set mysql installation directory basedir =/usr/local/mysql #Set the data storage directory of mysql database datadir = /usr/local/mysql/data #Set port port = 3306 socket = /tmp/mysql.sock #Set character set character-set-server=utf8 #Log storage directory log-error = /usr/local/mysql/data/mysqld.log pid-file = /usr/local/mysql/data/my ...

0. Introduction Recently, when synchronizing part of the company's mysql data to es, the Logstash input JDBC for full synchronization，Incremental synchronization with canal However, another problem is that the data structure in ES needs to be redesigned, which leads to the need for some mysql fields to be transformed and then synchronized to ...

MySQL Learning Series For some very performance-consuming statements, MySQL still tries its best to convert this bad statement into a more efficient form according to some rules. This process can also be called query rewriting. Conditional simplification The search condition of the query statement we write is essentially an expression. The ...

1. Overview of new MySQL8 features 1.1 MySQL8.0 New Features 1. Simpler NoSQL support NoSQL refers generally to non-relational databases and data storage. With the rapid development of Internet platform, traditional relational databases have become increasingly unsatisfactory. MySQL has been supporting simple NoSQL storage since version 5.6. ...