1, Core concept
1.1 Elasticsearch is document oriented, relational database, and comparison with Elasticsearch
Elasticsearch file storage. Elasticsearch is a document oriented database. A piece of data is a document here, and JSON is used as the format of document serialization
relational databasedatabasesurfacethat 's okColumnsElasticsearch ...
Posted by Braclayrab on Wed, 27 Apr 2022 16:36:36 +0300
1, Master-slave replication and its principle
concept Master-Slave replication refers to copying data from one redis server to other redis servers. The former is called master/leader and the latter is called slave/follower; Data replication is unidirectional and can only be from master node to Slave node,. Mater is mainly written and Slave is ...
Posted by carnot on Wed, 27 Apr 2022 09:08:43 +0300
Chapter 124 SQL function SECOND
A time function that returns the number of seconds of a datetime expression.
Time expression - an expression that is a column name, the result of another scalar function, or a string or numeric literal. It must resolve to a TimeStamp string or a $HOROLOG st ...
Posted by markyoung1984 on Wed, 27 Apr 2022 04:40:43 +0300
Now let's introduce the construction of high availability architecture of MHA database. First, let's introduce the steps of installing MHA node node on the machine where the three databases are located. First, perl language environment must be installed first. This is the same as normal Java development. JDK must be installed first! So you can ...
Posted by nogeekyet on Tue, 26 Apr 2022 08:36:51 +0300
1, Concept of index
● index is a sorted list in which the index value and the physical address of the row containing the data of this value are stored (similar to the linked list of C language, pointing to the memory address of the data record through a pointer).
● after using the index, you can not scan the whole table to locate the data ...
Posted by Sirus121 on Tue, 26 Apr 2022 02:55:33 +0300
Mysql version: 8.0.19 Kubernetes version: 1.17.4 Operating system version: CentOS 7.8
Mysql is a commonly used relational database. It is often necessary to deploy a set of Mysql for data storage when the project is developed, tested and deployed to the generation environment. Here's how to deploy Mysql ...
Posted by itsjames on Tue, 26 Apr 2022 00:25:10 +0300
Steps to apply mybatis:
Introduction to mybatis
Dependent configuration. Operation:
1. Create a new entity class. The attributes in the class correspond to those in the database
2. Create a new dao interface and write the methods you need (for example, return all list sets).
3. Create a new XML file named sqlmapconfig in resource XML (main ...
Posted by horsleyaa on Mon, 25 Apr 2022 22:34:44 +0300
ClickHouse From Beginning to Proficiency (3)
Explain View Execution Plan
To view the execution plan of an sql statement before Clickhouse version 20.6, you need to set the log level to trace in order to see it, and you can only actually execute sql and view it in the execution log. Native execution plan syntax was int ...
Posted by Harbinger on Mon, 25 Apr 2022 19:06:16 +0300
Spring boot integrates sharding JDBC to realize annual database and monthly table (implementation and brief analysis)
This scheme is applicable to the horizontal segmentation of data with high time dependence. If you just meet the requirements, you can take a look at this article. If you do not meet the requirements, you can also ...
This article was first published in Nebula Graph Community official account
Just learned the content of graph data. At present, the Internet is full of a large number of installation documents, which are uneven, and the deployment is very troublesome.
Now I'm sorting out a relatively complete installation document for your refer ...
Posted by ricmetal on Mon, 25 Apr 2022 06:55:24 +0300