Detailed explanation of Redis caching problems

cache penetrationCache penetration means that the data requested by the client does not exist in the cache and the database, so the cache will never take effect, and these requests will hit the databaseIf a malicious user uses countless threads to concurrently access non-existent data, these requests will all reach the database, which is likely ...

Posted by bliss322 on Sun, 25 Sep 2022 21:01:59 +0300

Redis advanced practice

Redis advanced practice transaction management Comparison between redis and mysql redis slow log queryredis high availability and cluster redis master-slave replication Synchronization mechanism**Master slave replication principle****Command propagation**SYNC and PSYNCConsistency of redis replication ...

Posted by ben2.0 on Sat, 27 Aug 2022 14:01:57 +0300

Supplementary record of sql basic syntax (to be continued 8 / 25)

I haven't done this for a long time. By the way, I was asked about it during the interview 1, distinct 1) Function Remove duplicate items 2) Grammar select distinct Column name from Table name; give an example Before use:(Here you can see that 3 repeat) select client ID from Orders; After use:(It can be seen here that onl ...

Posted by dlebowski on Thu, 25 Aug 2022 12:39:11 +0300

MySQL advanced - six index optimization

Database optimization scheme Index failure, insufficient use of index: index establishmentToo many JOIN (design defects or unavoidable requirements) associated queries: SQL optimizationToo much data: sub database and sub tableServer tuning / optimization and various parameter settings (buffer, number of threads, etc.): adjust my.cnf Performan ...

Posted by tanita on Sat, 06 Aug 2022 21:43:39 +0300

JDBC operation data and DAO design pattern in actual combat

Using JDBC to manipulate data 1. Using JDBC to write large text data to the database Purpose: to java and other text files are written to the corresponding fields of the corresponding table by connecting the database with JDBC. 1. Table structure 2. Documents 3. Implementation code for inserting text package LoadFileTest; import driver.JDB ...

Posted by schoi on Wed, 25 May 2022 18:54:45 +0300

MySql advanced master-slave synchronization ☆

Master slave synchronization of MySql advanced 1. Replication overview This means that the master and slave databases can be synchronized again by transferring these data to the master and slave databases through the DDL. MySQL supports the replication of one master database to multiple slave databases at the same time. The slave database ca ...

Posted by upit on Wed, 25 May 2022 17:55:35 +0300

Database: mysql:undo log

1, Definition Files required for transaction rollback. 2, Function Rollback the transaction MVCC control: when a user reads a row of record, if the record has been occupied by other transactions, the current transaction can read the previous row version information through undo log, so as to realize consistent non locking reading. The snapsho ...

Posted by itsjareds on Wed, 25 May 2022 13:51:44 +0300

plsql, cursor, stored procedure

The following are personal study notes The plsql language is case insensitive. 1. Program structure: Plsql is divided into three parts: declaration part, executable part and exception handling part. Syntax: declare --Declaring variables, cursors i integer; begin --Execute statement --exception handling end; Example: print hello world ...

Posted by bnmng on Wed, 25 May 2022 12:34:32 +0300

Meituan distributed ID generator (Leaf), which can't be missed, is an easy-to-use batch

Leaf Leaf is a distributed ID generation service launched by meituan. Its name is taken from the words of German philosopher and mathematician Leibniz: "there are no two identity leaves in the world." ("there are no two same leaves in the world"), taking a name has such moral meaning, meituan programmer Niu break! Advantag ...

Posted by Chris_Evans on Wed, 25 May 2022 07:06:18 +0300

[Study Notes] Alibaba Cloud Tianchi Dragon Ball Project SQL Training Camp - Task03: Complex Query Methods - Views, Subqueries, Functions, etc.

s This note is the learning content of Alibaba Cloud Tianchi Dragon Ball Project SQL Training Camp The link is: https://tianchi.aliyun.com/specials/promotion/aicampsql   Practice Questions - Part 1 3.1 Create a view that satisfies the following three conditions (the view name is ViewPractice5_1). Using the product table as a referen ...

Posted by [e]r!k on Wed, 25 May 2022 06:53:14 +0300