'Hashing' diaporamas de présentation

1.03k views • 89 slides

Cuckoo Hashing and CAMs

Cuckoo Hashing and CAMs. Michael Mitzenmacher. Background. For the past several years, I have had funding from Cisco to research hash tables and related data structures for approximate measuring/monitoring on routers. Extreme conditions: Limited space. Limited # of memory accesses.

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Advanced Data Structures NTUA Spring 2007 B+-trees and External memory Hashing

Advanced Data Structures NTUA Spring 2007 B+-trees and External memory Hashing. Model of Computation. Data stored on disk(s) Minimum transfer unit: a page(or block) = b bytes or B records N records -> N/B = n pages I/O complexity: in number of pages. CPU. Memory. Disk.

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Overview(1)

Overview. Overview(1). O(1) access to files Variation of the relative file Record number for a record is not arbitrary; rather, it is obtained by a hashing function H applied to the primary key, H(key)

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Access Paths

Access Paths. Chapter 20. Types of Associative Access Paths. Primary index: Given the primary key value, find the tuple. Secondary index: Given the value of a non-unique attribute, find all qualified tuples.

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Cryptography Revealed

Cryptography Revealed. Ayman Saeed. Agenda. Cryptography ?? . Encryption . Symmetric Encryption . Asymmetric Encryption. Diffie-hellman. Hashing . Digital signature . Authentication Protocols . PKI . Cryptosystems . Cryptanalysis . Quantum Cryptography. Cryptography ?? .

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Hash table

Hash table. A basic problem. We have to store some records and perform the following: add new record delete record search a record by key Find a way to do these efficiently!. Unsorted array. Use an array to store the records, in unsorted order

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CSCE 3400 Data Structures & Algorithm Analysis

CSCE 3400 Data Structures & Algorithm Analysis. Hashing Reading: Chap.5, Weiss. How to Implement a Dictionary?. Sequences ordered unordered Binary Search Trees Hashtables. Hashing. Another important and widely useful technique for implementing dictionaries

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Hashing

Hashing. How to Implement a Dictionary?. Sequences ordered unordered Binary Search Trees Skip lists Hashtables. Hashing. Another important and widely useful technique for implementing dictionaries Constant time per operation (on the average)

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Stadium H ashing: Scalable and Flexible Hashing on GPUs

Stadium H ashing: Scalable and Flexible Hashing on GPUs. Farzad Khorasani, Mehmet E. Belviranli , Rajiv Gupta, Laxmi N. Bhuyan University of California Riverside. What Stadium hashing addresses. Out-of-core GPU hashing.

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Database Systems ( ????? )

Database Systems ( ????? ). November 8, 2004 Lecture #9 By Hao-hua Chu ( ??? ). Announcement. Midterm exam: November 20 (Sat): 2:30 PM in CSIE 101/103 Assignment #6 is available on the course homepage. It is due on 11/24 It is very difficult Suggest you do it before midterm exam

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Data Structures and Algorithms Hashing First Year

Data Structures and Algorithms Hashing First Year. M. B. Fayek CUFE 2009. Hashing. What is Hashing? Problems in hashing Collision Resolution Strategies. 1. What is Hashing?. Hashing is a quick and efficient searching technique .

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Hashing Algorithm

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CSE 326: Data Structures Lecture #13 Extendible Hashing and Splay Trees

CSE 326: Data Structures Lecture #13 Extendible Hashing and Splay Trees. Alon Halevy Spring Quarter 2001. Extendible Hashing. Hashing technique for huge data sets optimizes to reduce disk accesses each hash bucket fits on one disk block better than B-Trees if order is not important

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CSC 2300 Data Structures & Algorithms

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Cryptography Basics

Cryptography Basics. Henry Wise Wood Math and Computer Science Club December 12, 2011. Why do I need Cryptography?. Confidentiality Ensuring that only intended recipients can read a message

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Hash File

Hash File. Considerations. Hashing - Hash File Considerations. Statistical Considerations Record Distribution is important Ideal - one record per location Load Factor - How full the file is Load Factor = r / b * m r - number of records stored b - bucket size m - number of addresses.

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6.830 Lecture 7

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Chapter 48 Hashing

Chapter 48 Hashing. Objectives. To know what hashing is for (§48.3). To obtain the hash code for an object and design the hash function to map a key to an index (§48.4). To handle collisions using open addressing (§48.5).

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Tree-based Indexing

Tree-based Indexing. Hessam Zakerzadeh. ISAM ( Indexed Sequential Access Method ). Static index structure. Effective when file is not frequently updated. Data values reside in leaf nodes. Overflow . page. Non-leaf. Pages. Leaf. Pages. Primary pages. Leaf pages contain data entries .

745 views • 9 slides