Sql Server Multiple Primary Keys

The logical design of database is a very broad problem. In this paper, the main key design of the table is discussed in the design of MS SQL Server, and the corresponding solutions are given. Primary key design status and problems about database table primary key design, in general, based on business requirements, based on business logic, the formation of primary key. For example, when sales to record sales, generally need two tables, one is the summary description of the sales list, records such as sales number, the total amount of a class of cases, and the other table record of each commodity ...

With the proliferation of data volume, Mysql+memcache has not met the needs of large-scale Internet applications, many organizations have chosen Redis as its architectural complement, however, redis the use of the threshold is not low, such as not supporting SQL, here for everyone to share the Redis use of the full raiders. Redis, one of the most closely watched NoSQL databases, has been used by many well-known internet companies, such as Sina Weibo, Pinterest and Viacom. However, being born with no support for SQL makes him look difficult ...

1. The operation of data and log files stored separately on different disks for data files and log files produces a large amount of I/O. 　　Where possible, the log file should be stored on a hard disk that is different from the data file where the data and index are located to distribute I/O, while also facilitating disaster recovery for the database. 2.tempdb databases are stored on separate disks the tempdb database is a temporary database that all other databases are likely to use. When you use SELECT INTO to execute the by by on a column that is not indexed ...

First, the Hadoop project profile 1. Hadoop is what Hadoop is a distributed data storage and computing platform for large data. Author: Doug Cutting; Lucene, Nutch. Inspired by three Google papers 2. Hadoop core project HDFS: Hadoop Distributed File System Distributed File System MapReduce: Parallel Computing Framework 3. Hadoop Architecture 3.1 HDFS Architecture (1) Master ...

The hardware environment usually uses a blade server based on Intel or AMD CPUs to build a cluster system. To reduce costs, outdated hardware that has been discontinued is used. Node has local memory and hard disk, connected through high-speed switches (usually Gigabit switches), if the cluster nodes are many, you can also use the hierarchical exchange. The nodes in the cluster are peer-to-peer (all resources can be reduced to the same configuration), but this is not necessary. Operating system Linux or windows system configuration HPCC cluster with two configurations: ...

In the new field of Big data, BigTable database technology is well worth our attention because it was invented by Google, and Google is a well-established company that specializes in managing massive amounts of data. 　　If you know this well, your family is familiar with the two Apache database projects of Cassandra and HBase. Google first bigtable in a 2006 study. Interestingly, the report did not use BigTable as a database technology, but ...

Cassandra and HBase are the representatives of many open source projects based on bigtable technology that are implementing high scalability, flexibility, distributed, and wide-column data storage in different ways. In this new area of big data [note], the BigTable database technology is well worth our attention because it was invented by Google, and Google is a well-established company that specializes in managing massive amounts of data. If you know this very well, your family is familiar with the two of Cassandra and HBase.

This time, we share the 13 most commonly used open source tools in the Hadoop ecosystem, including resource scheduling, stream computing, and various business-oriented scenarios. First, we look at resource management.

This paper is an excerpt from the book "The Authoritative Guide to Hadoop", published by Tsinghua University Press, which is the author of Tom White, the School of Data Science and engineering, East China Normal University. This book begins with the origins of Hadoop, and integrates theory and practice to introduce Hadoop as an ideal tool for high-performance processing of massive datasets. The book consists of 16 chapters, 3 appendices, covering topics including: Haddoop;mapreduce;hadoop Distributed file system; Hadoop I/O, MapReduce application Open ...

The cloud storage Standard--CDMI specification, published by SNIa in April 2010, may have been a thrill for cloud-storage-related vendors, but how much does it do for the security and stability of cloud storage and the scalability of the current user's suspicions?     We don't know. Cloud storage was originally a concept that came out after cloud computing, but it didn't come up with a standard before cloud computing. This also fulfilled the phrase Bill Gates once said: "Cloud storage will be faster than cloud computing." Cloud ...