Multiple Join Query

Based on MapReduce skyline-join query algorithm Sun Dalie, Li Jianzhong Skyline query is a very time-consuming operation, while Skyline queries involving multiple tables (Skyline-join query) will bring more load to the database system, Thus affecting the response time of the whole system. To solve this problem, a Skyline-join query processing algorithm for MapReduce parallel processing framework based on Google design is proposed.

The example demonstrates using the IBM BCU design architecture to benchmark TPC as data source (300GB data volume) and test case, showing the pull effect of "troika" on query performance. Whether in the POC test or in the real production system, query performance is an important indicator of customer concern. Through this article, the reader can fully understand the "troika" of the mystery, the text of the example demo to the reader has reference and referential significance. In the Http://www.aliyun.com/zixun/aggreg ...

ADO. NET is the core of. NET interoperability with the database, and the Ado.net entity database enhances the ability of the. NET application to interconnect with the database, and we can easily strongly type data interoperation with the underlying database through the Ado.net Entity Data model. Greatly facilitates the design personnel, thus also enhances the database operation security. A very special problem has recently been encountered when using the domain data service to siverlight [the results in the application are not the same as the results of the database], after repeated experiments, finally found ...

In our development of the efficiency has been a problem, especially for a lot of large data operations, today we ran into a random query data, at first we may think of the simplest order by RAND () to operate but the efficiency is not flattering ah. Recently, because of the need to study the MySQL random extraction implementation method. For example, to randomly extract a record from the TableName table, the general wording is: SELECT * from TableName ORDER by RAND () LIM ...

Recently due to the need to study about MYSQL based random extraction method. For example, to randomly extract a record from the table table, we generally write: SELECT * FROM tablename ORDER BY RAND () LIMIT 1. However, I checked the official MYSQL manual, which prompts for RAND () probably means that the ORDER BY clause can not be used inside the RAND () function, because this will lead to multiple data columns were swept ...

Method 1 delete yourtable where [id] not in (select max ([id]) from yourtable group by (name + value) b on a.id = b.id where b.id ...

The greatest fascination with large data is the new business value that comes from technical analysis and excavation. SQL on Hadoop is a critical direction. CSDN Cloud specifically invited Liang to write this article, to the 7 of the latest technology to do in-depth elaboration. The article is longer, but I believe there must be a harvest. December 5, 2013-6th, "application-driven architecture and technology" as the theme of the seventh session of China Large Data technology conference (DA data Marvell Conference 2013,BDTC 2013) before the meeting, ...

Intermediary transaction SEO diagnosis Taobao Guest Cloud mainframe Technology Hall Yahoo spokeswoman said Loki studio was Yahoo's fourth acquisition this month and Yahoo's tenth acquisition since July last year. Last July, Ms. Mayer launched an ambitious plan to target start-ups that "meet the direction of Yahoo's business". Ms. Mayer then pointed out that she would be involved in completing 20 such acquisitions during her time at Google. Now, 6 months later, she has bought 10 start-ups. According to our statistics, at least 62 ...

Hive is optimized for different queries, and optimization can be controlled by configuration, this article will introduce some of the optimization strategies and optimization control options. Column cropping (columns pruning) When reading data, read only the columns that are needed in the query, ignoring the other columns. For example, for queries: SELECT a,b from T WHERE e < 10; Where T contains 5 columns (a,b,c,d,e), the column c,d will be ignored and only read A, B, e column ...

Using hive, you can write complex MapReduce query logic efficiently and quickly. In some cases, however, the Hive Computing task can become very inefficient or even impossible to get results, because it is unfamiliar with data attributes or if the Hive optimization convention is not followed. A "good" hive program still needs to have a deep understanding of the hive operating mechanism. Some of the most familiar optimization conventions include the need to write large tables on the right side of the join, and try to use UDF instead of transfrom ... Like。 Here are 5 performance and logic ...