在开始搜索物理plan之前,先要有必要的统计信息才可以计算相关的代价,因此有一个收集+生成统计信息的过程。在Orca中,这个统计信息主要就是指一系列的column histograms,用它来做Cardinality Estimation和检测data skew。 这里针对每个group的statistics,提出了一个非常有趣的概念:[2],Statistics promise。我们都知道统计信息...
[6] R. Chaiken, B. Jenkins, P.- ̊A. Larson, B. Ramsey,D. Shakib, S. Weaver, and J. Zhou. SCOPE: Easy and Efficient Parallel Processing of Massive Data Sets. PVLDB, 1(2), 2008. [7] L. Chan. Presto: Interacting with petabytes of data at Facebook. http://prestodb.io, 20...
上一步结束后产生了所有可能的逻辑搜索空间,开始进入Statistics Derivation,为每个memo group获取统计信息,列的直方图,用来统计cardinality和data skew。 统计信息只和逻辑expr相关,和物理expr无关,因此在这个阶段获取统计信息,如果放到后面物理变换之后,memo空间就变大了。 Statistics promise 一个InnerJoin的group需要计算最...
Define big data architecture. big data architecture synonyms, big data architecture pronunciation, big data architecture translation, English dictionary definition of big data architecture. n. 1. An incandescent particle, especially: a. One thrown off fr
be used; Thirdly, the architecture of big data is discussed along with the different models of Big data; Fourthly, what are some potential applications of big data and how will it make the job easier for the persisting machines and users; Finally, we will discuss the future of Big data.do...
In fact, series of sophisticated processes are involved in Big Data services. However, there exists a structural gap, which is holding back the development of Big Data services. In this paper, a four-layer cloud-based network architecture is proposed to support Big Data services. The proposed ...
INTRODUCTION Big Data has brought about a renewed interest in query optimization as a new breed of data management systems has pushed the envelope in terms of unprecedented scal- ability, availability, and processing capabilities (cf. e.g., [9, 18, 20, 21]), which makes large datasets of ...
will concentrate on better ways to analyze, use and manage all of the information they've been dumping intodata lakes. Their efforts will include tuning the storage architecture for big data with the assistance of increasing numbers of tools designed to integrate, engineer and orchestrat...
2.1 Components of big data architecture [4] The big data architecture accommodates some or all the following components (Fig. 1). Sign in to download hi-res image Fig. 1. Components of big data architecture. Source of data is the basic of big data architecture. The source of data can ...
The amount of data produced by sensors, social and digital media, and Internet of Things (IoTs) are rapidly increasing each day. Decision makers often need to sift through a sea of Big Data to utilize information from a variety of sources in order to det