03 May 2018

Data Science: Hashing (Definitions)

"A technique for providing fast access to data based on a key value by determining the physical storage location of that data." (Jan L Harrington, "Relational Database Dessign: Clearly Explained" 2nd Ed., 2002)

"A mathematical technique for assigning a unique number to each record in a file." (S. Sumathi & S. Esakkirajan, "Fundamentals of Relational Database Management Systems", 2007)

"A technique that transforms a key value via an algorithm to a physical storage location to enable quick direct access to data. The algorithm is typically referred to as a randomizer, because the goal of the hashing routine is to spread the key values evenly throughout the physical storage." (Craig S Mullins, "Database Administration", 2012)

"A mathematical technique in which an infinite set of input values is mapped to a finite set of output values, called hash values. Hashing is useful for rapid lookups of data in a hash table." (Oracle, "Database SQL Tuning Guide Glossary", 2013)

"An algorithm converts data values into an address" (Daniel Linstedt & W H Inmon, "Data Architecture: A Primer for the Data Scientist", 2014)

"The technique used for ordering and accessing elements in a collection in a relatively constant amount of time by manipulating the element’s key to identify the element’s location in the collection" (Nell Dale et al, "Object-Oriented Data Structures Using Java" 4th Ed., 2016)

"The application of an algorithm to a search key to derive a physical storage location." (George Tillmann, "Usage-Driven Database Design: From Logical Data Modeling through Physical Schmea Definition", 2017)

"Hashing is the process of mapping data values to fixed-size hash values (hashes). Common hashing algorithms are Message Digest 5 (MD5) and Secure Hashing Algorithm (SHA). It’s impossible to turn a hash value back into the original data value." (Piethein Strengholt, "Data Management at Scale", 2020)

"A mathematical technique in which an infinite set of input values is mapped to a finite set of output values, called hash values. Hashing is useful for rapid lookups of data in a hash table." (Oracle, "Oracle Database Concepts")

"A process used to convert data into a string of numbers and letters." (AICPA)

"A technique for arranging a set of items, in which a hash function is applied to the key of each item to determine its hash value. The hash value identifies each item's primary position in a hash table, and if this position is already occupied, the item is inserted either in an overflow table or in another available position in the table." (IEEE 610.5-1990)

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