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  Description of kernel parameters for installing oracle database under Linux

  The following kernel parameters need to be configured when installing the database: fs.aio-max-nr = 1048576fs.file-max = 6815744kernel.shmall = 2097152kernel.shmmax =

  2022-06-01 15:00:09 Views: 286
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  Optimization skills of SQL sentences

  1. Try to avoid using the! = or < > operator in the where clause, otherwise the engine will give up using the index and do a full table scan. 2. In order to optimize the query, we should try our best to avoid full table scanning. First of all, we should consider establishing an index on the columns involved in where and order by.

  2022-06-01 15:00:09 Views: 300
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  Oracle- subquery

  1. Subquery in WHERE condition 1. What are the employees who earn more than black? select enamefrom empwhere sal > (select sal from empwhere ename='BLA

  2022-06-01 15:00:09 Views: 241
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  Simple entry-level application of Zabbix

  Zabbix: an enterprise-level open source solution based on WEB interface that provides distributed system monitoring and network monitoring capabilities. It is a very powerful tool. Generally speaking, zabbix chooses mysql to store data, so when more and more hosts are monitored by zabbix

  2022-06-01 14:59:39 Views: 269
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  MongoDB startup parameters (to be translated)

  . / mongod-- helpOptions:General options:-h [--help] show this usage information--version show versi

  2022-06-01 14:59:38 Views: 226
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  Introduction to locks in mysql database

  This article will explain in detail about the lock introduction in the mysql database. The content of the article is of high quality, so the editor shares it for you as a reference. I hope you will have a certain understanding of the relevant knowledge after reading this article. Mysql locking mechanism is that the database makes the data consistent.

  2022-06-01 14:59:23 Views: 282
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  Database left connection, right connection, full connection, left outer, right outer, full outer

  Inline SELECT*FROMtemployee employees0INNER JOIN tcustomer customer1 ON (customer1.id = employees0.id)

  2022-06-01 14:59:23 Views: 275
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  The problem of adding nulls and numbers in Oracle

  Select 10 + 10 + 10 from dual result is 30, no problem at all. The result of select null + 10 + 10 from dual is an empty string, but the expected result is 20. Select nvl (n)

  2022-06-01 14:59:23 Views: 282
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  Deploy zabbix Monitoring mysql (1) install zabbix

  Deploy zabbix Monitoring mysql (1) install LAMP environment [root@localhost ~] # yum-y installmysql-server http php (2) what is needed to install zabbix web

  2022-06-01 14:58:53 Views: 281
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  The function of transaction Log in mysql Database

  This article will explain in detail the role of transaction logs in the mysql database. The content of the article is of high quality, so the editor shares it for you as a reference. I hope you will have a certain understanding of the relevant knowledge after reading this article. Mysql transaction logs can help improve the efficiency of transactions. Things

  2022-06-01 14:58:53 Views: 245
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  Shiro tutorial (4)-shiro and Project Integrated Development

  1 shiro and project integration development 1.1 shiro and springweb project integration shiro and springweb project integration on the basis of "engineering based on url interception implementation", the technical architecture of the project based on url interception implementation is spri

  2022-06-01 14:58:25 Views: 262
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  What is the clustering index in mysql

  What is the clustering index in mysql? Many novices are not very clear about this. In order to help you solve this problem, the following editor will explain it in detail. People with this need can come and learn. I hope you can gain something. Clustering index, also known as cluster index, is a kind of real-time on disk.

  2022-06-01 14:58:25 Views: 245
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  Sentinel of redis High availability solution (Sentinel Cluster)

  Today, I would like to introduce to you the high availability scheme of redis, the sentinel that comes with redis, and a simple oral description of what is sentinel (Sentinel Cluster). Sentinel cluster can encapsulate redis master and slave to achieve redis master downtime.

  2022-06-01 14:58:19 Views: 275
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  What is the difference between clustered index and non-clustered index in mysql

  What is the difference between clustered index and non-clustered index in mysql? In view of this problem, this article introduces the corresponding analysis and answers in detail, hoping to help more partners who want to solve this problem to find a more simple and feasible way. In general, indexing is an effective hand to speed up queries

  2022-06-01 14:58:18 Views: 236
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  Introduction to the index types of mysql

  In this issue, the editor will introduce the index types of mysql. The article is rich in content and analyzes and narrates it from a professional point of view. I hope you can get something after reading this article. Mysql currently has the following main index types: Full-text,H

  2022-06-01 14:58:18 Views: 252
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  What is myisam in mysql

  What is myisam in mysql? In view of this problem, this article introduces the corresponding analysis and answers in detail, hoping to help more partners who want to solve this problem to find a more simple and feasible way. Myisam introduces MyISAM as the default storage engine (Mysql

  2022-06-01 14:58:18 Views: 284
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  Proxysql configuration information cleanup, backup, restore

  1. Immediately following the above, please see the configuration process above 2. Enter the proxysql data directory [root@12c proxysql] # cd / var/lib/proxysql/ [root@12c proxysql] # lltota

  2022-06-01 14:58:00 Views: 239
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  SSH series: (26) acceptance of complaints

  1. Hibernate reverse Engineering 1.1, CDM Conceptual Model although T_Complain is used here, it is not recommended to do so, because when the JavaBean class is generated later, the TComplain.java class will be generated instead of Complain.

  2022-06-01 14:58:00 Views: 227
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  Slow query of mongodb

  Slow query log in mongodb 1. Open the query log. (1) when it is enabled dynamically, you can selectively enable the slow query log for the specified DB, but the slow query log has to be manually opened after the server is restarted. Db.setProfilingLevel (1300) set

  2022-06-01 14:57:48 Views: 255
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  Zabbix data structure and parallel Computing implementation

  The original author of this article, Bao Guangya, the software development engineer of JD.com Mall basic platform Department, published on my blog with the consent of the author, if you need to reprint it, you need my consent. Preface our department uses the open source Zabbix system to monitor the database, which currently monitors tens of thousands of hosts. The purpose of this paper is to divide into

  2022-06-01 14:57:48 Views: 212