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  Why should we keep column as NOT NULL instead of NULL in MySQL?

Keep table column as NOT NULL instead of NULL except in some special cases. This statement is cited by many articles of MySQL optimization, but they don't say why we should do this. Here we discuss about this. First why are there many people using NULL when defining table? The reasons may be: NULL the the default when defining table, the rookies or people who don't want to have much troubles will keep this default setting Many people think NOT NULL will require more space Many people don't want...

   MySQL,NULL,reason     2012-10-27 03:21:27

  How expensive is a MySQL query?

Database access speed is always the bottle neck of many applications. Many application have large amount of data to search, retrieve and display nowadays. How do we improve the performance of our applications, how do we reduce the cost of database access? Apart from the design of database, the quality of the query is also one important factor to take care.  But before that, we need to know how much network traffic a query will consume. Yunyang,Zhang from Nubee in Singapore did some research...

   MySQL,Network traffic,Query     2013-04-09 05:13:33

  A guide on installing and running Clickhouse on macOS

ClickHouse is a high-performance open-source columnar database management system developed by Yandex. Here are some of the key features of ClickHouse: Columnar storage: ClickHouse uses a columnar storage format, which allows it to efficiently store and retrieve data by column, rather than by row. This results in much faster query performance, especially for analytical and aggregate queries. Real-time data processing: ClickHouse is designed to handle real-time data processing and can handle bill...

   CLICKHOUSE,MACOS     2023-02-15 06:04:55

  Change password of postgres account in Postgres

When installing Postgres on Windows, there is some default account created for user to login. One of them is postgres, but we often don;t know what's the password for this account when we first login using this account. We need to change the password for this account. How to change it? Step 1. Modify the pg_hba.conffile Go to the /data/ and open the pg_hba.conf. # TYPE  DATABASE        USER            ...

   Postgres,password, user account     2013-03-04 01:51:02

  Update & Delete Kubernetes resources in one-line command

It recently troubles me that my GKE cluster is managing more and more resources and causing difficulties in maintenance, one of which involves how to delete resources properly. Next, I will explain step by step the difficulties I encountered in my work and how I finally used the combination of bash commands and kubectl to implement the edition of Kubernetes objects through one-line command. In general The following are the basic operations that almost every Kubernetes user takes. Check ðŸ‘...

   KUBERNETES     2020-11-01 04:16:47

  Which programming language should I learn first?

Recently I saw somebody asked a question in a forum, the question is "Which programming language should I learn first?". Then someone answered this question. His answer:Depends. To program in an expressive and powerful language: PythonTo get a website up quickly: PHPTo mingle with programmers who call themselves “rockstars”: Ruby.To really learn to program: C.To achieve enlightenment: Scheme.To feel depressed: SQLTo drop a chromosome: Microsoft Visual BasicTo get a guaranteed, m...

   Programming language,Learn,JavaScript,C     2012-04-29 02:59:17

  Do You Make These 5 Database Design Mistakes?

Look, everyone makes mistakes. It’s true. But not all of us have the chance to make mistakes that end up costing millions of dollars in hardware and production support costs. Any one of the following five mistakes listed below will add additional costs to your company. It’s guaranteed. The costs could be hardware related (extra disk space, network bandwidth), which tend to add up quickly. The costs are also support related (bad performance, database re-design, report cre...

   Database design,Mistake,Advice,Data type,Compatibility     2012-01-03 11:25:13

  SQLite C/C++ function interfaces

Some simple introduction to the SQLite function interfaces. First let's check some error codes defined in SQLite3 (They are in SQLite3.h file in the SQLite installation).#define SQLITE_OK           0   /* Successful result */  /* beginning-of-error-codes */  #define SQLITE_ERROR        1   /* SQL error or missing database */  #define SQLITE_INTERNAL     2&nb...

   SQLite,Function interface,C/C++     2012-07-04 12:23:43

  Top 5 Reasons Not to Use Hadoop for Analytics

As a former diehard fan of Hadoop, I LOVED the fact that you can work on up to Petabytes of data.  I loved the ability to scale to thousands of nodes to process a large computation job.  I loved the ability to store and load data in a very flexible format.  In many ways, I loved Hadoop, until I tried to deploy it for analytics.   That’s when I became disillusioned with Hadoop (it just "ain't all that"). At Quantivo, we’ve explored many ways to deploy H...

   Cloud computing,Hadoop,Analytics     2012-04-17 13:43:26

  SQL Grammar Summary

整理了一下，希望对大家有用SQL语句大全  --语 句 功 能--数据操作SELECT --从数据库表中检索数据行和列INSERT --向数据库表添加新数据行DELETE --从数据库表中删除数据行UPDATE --更新数据库表中的æ...

   SQL,Query,Summary,Select,Update,Delete,I     2011-05-20 12:04:55

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