PPT-Hashing

Martin Åkerblad William bruce What is Hashing Index Key 1 2 3 4 5 6 7 Key 56 84 23 42 71 97 55 Hash function 56 42 71 23 84 55 97 Value When to use hashing Quick searching in large databases. 1 Overview Hashing is a great practical tool with an interesting and su btle theory too In addition to its use as a dictionary data structure hashing also comes up in many di 64256erent areas including cryptography and complexity theory In this lectu Constant Worst-Case Operations with a Succinct Representation. Yuriy. . Arbitman. . Moni. Naor Gil . Segev. Dynamic Dictionary. Data structure representing a set of words . S. From a Universe . and. Algorithms. Course slides: Hashing. www.mif.vu.lt. /~. algis. 2. Data Structures for Sets. Many applications deal with sets.. Compilers have symbol tables (set of . vars. , classes). Dictionary is a set of words.. Hash Tables. Open Address Hashing. Goals . Open Address Hashing. Hash Tables: . Resolving Collisions. There are two general approaches to resolving collisions:. Open address hashing: . if a spot is full, probe for next empty spot. Yunchao. Gong. UNC Chapel Hill. yunchao@cs.unc.edu. The problem. Large scale image search:. We have a candidate image. Want to search a . large database . to find similar images. Search the . internet. Shannon Quinn. (with . thanks to William Cohen of Carnegie Mellon University, and J. . Leskovec. , A. . Rajaraman. , and J. Ullman of Stanford . University). First: Upcoming deadlines!. TONIGHT @ 11:59:59pm: Assignment 3!. Hashing & Partitioning. 1. Peng Sun. Server Load Balancing. Balance load across servers. Normal techniques: . Round-robin? . 2. Limitations of Round Robin. Packets of a single connection spread over several servers. Cyryptocurrency Project Proposal - Spring 2015. SHA Use in Bitcoin. SHA256 used heavily as bitcoin’s underlying cryptographic hashing function. Two examples (of many) are its use in the Merkle tree hash, as well as the proof of work calculation. Plan. I spent the last decade advising on numerous cases where hash tables/functions were used. A few observations on . What data structures I’ve seen implemented and where. What do developers think, were they need help. Consider a set of data with N data items stored in some data structure. We must be able to insert, delete & search for items. What are possible ways to do this? What is the complexity of each structure & method ?. In static hashing, function . h. maps search-key values to a fixed set of . B. . buckets, that contain a number of (K,V) entries.. . . Problem: d. atabases . grow . (or shrink) . with time. . If initial number of buckets is too small, and file grows, performance will degrade due to too much overflows.. Naifan Zhuang, Jun Ye, Kien A. Hua. Department of Computer Science. University of Central Florida. ICPR 2016. Presented by Naifan Zhuang. Motivation and Background. According to a report from Cisco, by 2019:. What is a hashing function?. Fingerprint for a given piece of data. Typically generated by a mathematical algorithm. Produces a fixed length string as its . output. Hashes are sometimes . called a . checksum or message digests. Amjad. . Daoud. , Ph.D.. http://iswsa.acm.org/mphf. Practical Perfect Hashing for very large Key-Value Databases . Abstract. This presentation describes a practical algorithm for perfect hashing that is suitable for very large KV (key, value)...