SEARCH KEYWORD -- PRIMARY INDEX

  How MySQL optmizes ORDER BY

In some situations, MySQL will just use an index to fulfill the requirement of an ORDER BY or GROUP BY statement without extra sorting. Although ORDER BY will not have the exact match with index, index can still be used as long as the portion that is not included in the index is included in the where clause. The following queries will all use index to process the ORDER BY or GROUP BY part: SELECT * FROM t1 ORDER BY key_part1,key_part2,... ;SELECT * FROM t1 WHERE key_part1=constant ORDER BY key_p...

   MySQL,index,ORDER BY,optimization     2012-11-13 11:01:05

  Read 10 new books from O'Reilly for free

Recently O'Reilly provided free access to some books. Some of them are even in early release status. Here we recommend 10 of them. 1、Mastering Perl 2、Git Pocket Guide 3、Vagrant: Up and Running 4、High Performance Browser Networking 5、802.11ac: A Survival Guide 6、Test-Driven Development with Python 7、Interactive Data Visualization for the Web 8、HTML5 Canvas 9、Programming JavaScript Applications 10、Agile Data Source : http://linu...

   O'Reilly,Free book,Early release     2013-07-03 07:56:20

  MySQL Index Merge Optimization Practices

In production environment databases, it is often seen that some SQL where conditions include: equal condition on a normal index + primary key range query + order by limit Although using a normal index would be more efficient, the system chooses to use index merge instead in some cases. This article explores such index merge situations. Index Merge Official Introduction   The Index Merge access method retrieves rows with multiple range scans and merges their results into one. Generall...

   INDEX MERGE,MYSQL,PRIMARY INDEX,SECONDARY INDEX     2024-09-10 04:52:26

  TIOBE : Objective-C overtakes C++

TIOBE recently released the programming community index for July. From the index,we can find that the biggest change is that Objective-C overtakes C++ as the 3rd most popular language among programmers. Because of the popularity of iPhone and iPad, Objective-C is used by more and more mobile developers who want to develop apps for Apple products. Also, many developers are willing to develop apps for Apple since they can gain more profit on Apple platform than on Android platform.C++ is mainly us...

   TIOBE,July,C++,Objective-C,overtake     2012-07-05 22:49:49

  JavaScript: Private variables

The first thing you often hear when talking about JavaScript is often “JavaScript doesn’t have visibility modifiers, hence it doesn’t support private variables”. This is only valid for 50%, because JavaScript indeed doesn’t have visibility modifiers (public, private, friend) but it has closures and function scopes. With these tools we can make variables private. Let’s take the following function: var names = ["Kenneth", "John", "Marc", "Robert"]; var lookup =...

   JavaScript,private variable,closure     2012-04-28 11:46:34

  TIOBE : C overtakes Java as the No.1 programming language

TIOBE has released the Programming Community Index for April 2012. The highlight of this month is that C overtakes Java as the No.1 programming language again. C language is liked by more and more developers of all ages. Due to the growing popularity of the Android platform, Java decline will not be obvious. Previously Java took a very long time to overtake C, now C once again returns to the throne. The battle between these two languages will continue.The top three are respectively, C, Jav...

   C.TIOBE,Java     2012-04-09 07:01:20

  Create Packed Indexes with MySQL

I am pretty much sure that you are aware of indexes which we are creating on database fields. Indexes are very useful to make your query search faster and improve the site performance. But the fact is that Indexes which we are creating on database tables also require some additional space on your hard disk and if you have not properly created these indexes than some t...

   MySQL,Compressed index,PACK_KEYS     2012-04-24 07:42:18

  TIOBE : Where is that next big programming language?

TIOBE has released the Programming Community Index for May 2012 a bit late. The top 3 languages do not change compared to last Month TIOBE : C overtakes Java as the No.1 programming language, they are still C,Java and C++. However, the share of Java is continuing dropping, Objective-C is steadily rising  Other languages which have rising trend are Visual Basic.NET，PL/SQL and Logo.The last 8 years not much has changed in the top 10 of the TIOBE index except for Objective-C (in) and Del...

   TIOBE,2012,May,King     2012-05-12 01:18:27

  Removing duplicates in sql

In modern web development, it’s standard practice to make use of a database abstraction layer, typically an Object-Relational Mapper based on either the Active Record pattern or the Data Mapper pattern. There are several pros and cons to this which are fairly well established, so I’ll spare us all from enumerating them all right now. One established pro worth mentioning is that these systems typically provide a high level interface for fetching data, often removing the need to ...

   SQL,Duplicate,Remove,Web design     2012-01-05 08:20:13

  TIOBE : What's the future of C#?

TIOBE released the programming language index for August 2012, the top 3 programming languages are still C, Java and Objective-C. Objective-C still performs well after it ranked 3rd place last month, it's still rising. Is there any possibilty Object-C will overtake Java in the near future? However, Microsoft's C# doesn't look so good. C# is generally recognized as the enterprise language with most modern and expressive features available today and C# has shown more downward trends in the past an...

   TIOBE,August,C#     2012-08-13 14:48:11

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