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Jaql
Jaql (pronounced "jackal") is a functional data processing and query language most commonly used for JSON query processing on big data. It started as an open source project at Google but the latest release was on 2010-07-12. IBM took it over as primary data processing language for their Hadoop software packagBigInsights Although having been developed for JSON it supports a variety of other data sources like CSV, TSV, XML. A comparison to other BigData query languages like PIG Latin and Hive QL illustrates performance and usability aspects of these technologies. Jaql supports lazy evaluation, so expressions are only materialized when needed. Syntax The basic concept of Jaql is source -> operator(parameter) -> sink ; where a sink can be a source for a downstream operator. So typically a Jaql program has to following structure, expressing a data processing graph: source -> operator1(parameter) -> operator2(parameter) -> operator2(parameter) -> operator3(parameter) -> ope ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Query Languages
Query languages, data query languages or database query languages (DQL) are computer languages used to make queries in databases and information systems. A well known example is the Structured Query Language (SQL). Types Broadly, query languages can be classified according to whether they are database query languages or information retrieval query languages. The difference is that a database query language attempts to give factual answers to factual questions, while an information retrieval query language attempts to find documents containing information that is relevant to an area of inquiry. Other types of query languages include: * Full-text. The simplest query language is treating all terms as bag of words that are to be matched with the postings in the inverted index and where subsequently ranking models are applied to retrieve the most relevant documents. Only tokens are defined in the CFG. Web search engines often use this approach. * Boolean. A query language that also s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lazy Evaluation
In programming language theory, lazy evaluation, or call-by-need, is an evaluation strategy which delays the evaluation of an expression until its value is needed (non-strict evaluation) and which also avoids repeated evaluations (sharing). The benefits of lazy evaluation include: * The ability to define control flow (structures) as abstractions instead of primitives. * The ability to define potentially infinite data structures. This allows for more straightforward implementation of some algorithms. * The ability to define partially-defined data structures where some elements are errors. This allows for rapid prototyping. Lazy evaluation is often combined with memoization, as described in Jon Bentley's ''Writing Efficient Programs''. After a function's value is computed for that parameter or set of parameters, the result is stored in a lookup table that is indexed by the values of those parameters; the next time the function is called, the table is consulted to determine whe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2008 Software
8 (eight) is the natural number following 7 and preceding 9. In mathematics 8 is: * a composite number, its proper divisors being , , and . It is twice 4 or four times 2. * a power of two, being 2 (two cubed), and is the first number of the form , being an integer greater than 1. * the first number which is neither prime nor semiprime. * the base of the octal number system, which is mostly used with computers. In octal, one digit represents three bits. In modern computers, a byte is a grouping of eight bits, also called an octet. * a Fibonacci number, being plus . The next Fibonacci number is . 8 is the only positive Fibonacci number, aside from 1, that is a perfect cube. * the only nonzero perfect power that is one less than another perfect power, by Mihăilescu's Theorem. * the order of the smallest non-abelian group all of whose subgroups are normal. * the dimension of the octonions and is the highest possible dimension of a normed division algebra. * the first number ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
XQuery
XQuery (XML Query) is a query and functional programming language that queries and transforms collections of structured and unstructured data, usually in the form of XML, text and with vendor-specific extensions for other data formats (JSON, binary, etc.). The language is developed by the XML Query working group of the W3C. The work is closely coordinated with the development of XSLT by the XSL Working Group; the two groups share responsibility for XPath, which is a subset of XQuery. XQuery 1.0 became a W3C Recommendation on January 23, 2007. XQuery 3.0 became a W3C Recommendation on April 8, 2014. XQuery 3.1 became a W3C Recommendation on March 21, 2017. Features XQuery is a functional, side effect-free, expression-oriented programming language with a simple type system, summed up by Kilpeläinen: XQuery provides the means to extract and manipulate data from XML documents or any data source that can be viewed as XML, such as relational databases or office documents. XQ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
XPath
XPath (XML Path Language) is an expression language designed to support the query or transformation of XML documents. It was defined by the World Wide Web Consortium (W3C) and can be used to compute values (e.g., strings, numbers, or Boolean values) from the content of an XML document. Support for XPath exists in applications that support XML, such as web browsers, and many programming languages. Overview The XPath language is based on a tree representation of the XML document, and provides the ability to navigate around the tree, selecting nodes by a variety of criteria. In popular use (though not in the official specification), an XPath expression is often referred to simply as "an XPath". Originally motivated by a desire to provide a common syntax and behavior model between XPointer and XSLT, subsets of the XPath query language are used in other W3C specifications such as XML Schema, XForms and the Internationalization Tag Set (ITS). XPath has been adopted by a number of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
JSONiq
JSONiq is a query and functional programming language that is designed to declaratively query and transform collections of hierarchical and heterogeneous data in format of JSON, XML, as well as unstructured, textual data. JSONiq is an open specification published under the Creative Commons Attribution-ShareAlike 3.0 license. It is based on the XQuery language, with which it shares the same core expressions and operations on atomic types. JSONiq comes in two syntactical flavors, which both support JSON and XML natively. # The JSONiq syntax (a superset of JSON) extended with XML support through a compatible subset of XQuery. # The XQuery syntax (native XML support) extended with JSON support through a compatible subset (the JSONiq extension to XQuery) of the above JSONiq syntax. Features JSONiq primarily provides means to extract and transform data from JSON documents or any data source that can be viewed as JSON (e.g. relational databases or web services). The major expressio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jq (programming Language)
jq is a very high-level lexically scoped functional programming language in which every JSON value is a constant. jq supports backtracking and managing indefinitely long streams of JSON data. It is related to the Icon and Haskell programming languages. The language supports a namespace-based module system and has some support for closures. In particular, functions and functional expressions can be used as parameters of other functions. The original implementation of jq was in C; gojq is a "pure Go" implementation. There is also a Rust implementation of a large subset of jq named jaq, for which a denotational semantics has been specified. gojq should run on any platform where Go is supported, and likewise for jaq and Rust. History jq was created by Stephen Dolan, and released in October 2012. It was famously described as being "like sed for JSON data". Support for regular expressions was added in jq version 1.5. A "wrapper" program for jq nameyqadds support for YAML, XM ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Where (SQL)
A WHERE clause in SQL specifies that a SQL Data Manipulation Language (DML) statement should only affect rows that meet specified criteria. The criteria are expressed in the form of predicates. WHERE clauses are not mandatory clauses of SQL DML statements, but can be used to limit the number of rows affected by a SQL DML statement or returned by a query. In brief SQL WHERE clause is used to extract only those results from a SQL statement, such as: SELECT, INSERT, UPDATE, or DELETE statement. Overview WHERE is an SQL reserved word. The WHERE clause is used in conjunction with SQL DML statements, and takes the following general form: SQL-DML-Statement FROM table_name WHERE predicate all rows for which the predicate in the WHERE clause is True are affected (or returned) by the SQL DML statement or query. Rows for which the predicate evaluates to False or Unknown (NULL) are unaffected by the DML statement or query. The following query returns only those rows from table ''myt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Directed Acyclic Graph
In mathematics, particularly graph theory, and computer science, a directed acyclic graph (DAG) is a directed graph with no directed cycles. That is, it consists of vertices and edges (also called ''arcs''), with each edge directed from one vertex to another, such that following those directions will never form a closed loop. A directed graph is a DAG if and only if it can be topologically ordered, by arranging the vertices as a linear ordering that is consistent with all edge directions. DAGs have numerous scientific and computational applications, ranging from biology (evolution, family trees, epidemiology) to information science (citation networks) to computation (scheduling). Directed acyclic graphs are sometimes instead called acyclic directed graphs or acyclic digraphs. Definitions A graph is formed by vertices and by edges connecting pairs of vertices, where the vertices can be any kind of object that is connected in pairs by edges. In the case of a directed graph, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Functional Programming
In computer science, functional programming is a programming paradigm where programs are constructed by Function application, applying and Function composition (computer science), composing Function (computer science), functions. It is a declarative programming paradigm in which function definitions are Tree (data structure), trees of Expression (computer science), expressions that map Value (computer science), values to other values, rather than a sequence of Imperative programming, imperative Statement (computer science), statements which update the State (computer science), running state of the program. In functional programming, functions are treated as first-class citizens, meaning that they can be bound to names (including local Identifier (computer languages), identifiers), passed as Parameter (computer programming), arguments, and Return value, returned from other functions, just as any other data type can. This allows programs to be written in a Declarative programming, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Google
Google LLC () is an American multinational technology company focusing on search engine technology, online advertising, cloud computing, computer software, quantum computing, e-commerce, artificial intelligence, and consumer electronics. It has been referred to as "the most powerful company in the world" and one of the world's most valuable brands due to its market dominance, data collection, and technological advantages in the area of artificial intelligence. Its parent company Alphabet is considered one of the Big Five American information technology companies, alongside Amazon, Apple, Meta, and Microsoft. Google was founded on September 4, 1998, by Larry Page and Sergey Brin while they were PhD students at Stanford University in California. Together they own about 14% of its publicly listed shares and control 56% of its stockholder voting power through super-voting stock. The company went public via an initial public offering (IPO) in 2004. In 2015, Google was reor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pig (programming Tool)
Apache Pig is a high-level platform for creating programs that run on Apache Hadoop. The language for this platform is called Pig Latin. Pig can execute its Hadoop jobs in MapReduce, Apache Tez, or Apache Spark. Pig Latin abstracts the programming from the Java MapReduce idiom into a notation which makes MapReduce programming high level, similar to that of SQL for relational database management systems. Pig Latin can be extended using user-defined functions (UDFs) which the user can write in Java, Python, JavaScript, Ruby or Groovy and then call directly from the language. History Apache Pig was originally developed at Yahoo Research around 2006 for researchers to have an ad hoc way of creating and executing MapReduce jobs on very large data sets. In 2007, it was moved into the Apache Software Foundation. Naming Regarding the naming of the Pig programming language, the name was chosen arbitrarily and stuck because it was memorable, easy to spell, and for novelty. Exampl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
