Hard Sql Queries

Designing 1 applications doesn't seem to be difficult, but it's not easy to achieve the optimal performance of the system. There are many choices in development tools, database design, application structure, query design, interface selection, and so on, depending on the specific application requirements and the skills of the development team. This article takes SQL Server as an example, discusses the application performance optimization techniques from the perspective of the background database, and gives some useful suggestions. 1 database design to achieve optimal performance in a good SQL Server scenario, the key is to have 1 ...

The operating language of the data is SQL, so many tools are developed with the goal of being able to use SQL on Hadoop. Some of these tools are simply packaged on top of the MapReduce, while others implement a complete data warehouse on top of the HDFs, while others are somewhere between the two. There are a lot of such tools, Matthew Rathbone, a software development engineer from Shoutlet, recently published an article outlining some common tools and scenarios for each tool and not ...

1.1: Increase the secondary data file from SQL SERVER 2005, the database does not default to generate NDF data files, generally have a main data file (MDF) is enough, but some large databases, because of information, and query frequently, so in order to improve the speed of query, You can store some of the records in a table or some of the tables in a different data file. Because the CPU and memory speed is much larger than the hard disk read and write speed, so you can put different data files on different physical hard drive, so that the execution of the query, ...

April 24, we released a preview version of the SQL Database base level (preview) and standard (preview) new service levels and new business continuity features. In this blog post, we delve into the performance of new levels in SQL Database. Begin with the need for change. We focus on performance (specifically predictable performance) in new service levels, driven primarily by strong customer feedback on SQL Database Web-Level and enterprise-class performance. Web-and enterprise-level performance ...

Google created a mapreduce,mapreduce cluster in 2004 that could include thousands of parallel-operation computers. At the same time, MapReduce allows programmers to quickly transform data and execute data in such a large cluster. From MapReduce to Hadoop, this has undergone an interesting shift. MapReduce was originally a huge amount of data that helped search engine companies respond to the creation of indexes created by the World Wide Web. Google initially recruited some Silicon Valley elites and hired a large number of engineers to ...

It is well known that the system reads data from memory hundreds of times times faster than it does from the hard disk. So now most of the application system, will maximize the use of caching (in memory, a storage area) to improve the system's operational efficiency. MySQL database is no exception. 　　Here, the author will combine their own work experience, with you to explore the MySQL database Cache management skills: How to properly configure the MySQL database cache, improve cache hit rate. 　　When will the application get the data from the cache? Database read from server ...

1, use the index to traverse the table faster. The index created by default is a non-clustered index, but sometimes it is not optimal. Under non-clustered indexes, the data is physically stored on the data page. Reasonable index design should be based on the analysis and prediction of various inquiries. In general: a. A large number of duplicate values, and often range query (>, <,> =, <=) and order by, group by occurred column, consider the establishment of cluster index; b. Column, ...

Currently Apache Software Foundation finally released the latest Hadoop2 data analysis platform, which also led to public opinion for the big leap forward in the great leap forward in big data, before Xiaobian wrote "Hadoop is big data applications and why not" A text on the domestic big data market situation analysis. Now Hadoop 2 release, as the media expected to stimulate big data applications and development? I think we must first look at Hadoop 2 what improvements? From the relevant reports, Hadoop 2 biggest improvement ...

1, use the index to traverse the table faster. The index created by default is a non-clustered index, but sometimes it is not optimal. Under non-clustered indexes, the data is physically stored on the data page. Reasonable index design should be based on the analysis and prediction of various inquiries. In general: a. There are a large number of duplicate values, and often range query (>, <,> =, <=) and order by, group by occurred columns, consider the establishment of cluster index; Column, and each column contains duplicate values ​​can be ...

This article, formerly known as "Don t use Hadoop when your data isn ' t", came from Chris Stucchio, a researcher with years of experience, and a postdoctoral fellow at the Crown Institute of New York University, who worked as a high-frequency trading platform, and as CTO of a start-up company, More accustomed to call themselves a statistical scholar.   　　By the right, he is now starting his own business, providing data analysis, recommended optimization consulting services, his mail is: stucchio@gmail.com. "You ...