The sort-merge join (also known as merge join) is a join algorithm and is used in the implementation of a relational database management system. The basic problem of a join algorithm is to find, for each distinct value of the join attribute, the set of tuples in each relation which display that value. The key idea of the sort-merge algorithm is to first sort the relations by the join attribute, so that interleaved linear scans will encounter these sets at the same time. In practice, the most expensive part of performing a sort-merge join is arranging for both inputs to the algorithm to be presented in sorted order. This can be achieved via an explicit sort operation (often an external sort), or by taking advantage of a pre-existing ordering in one or both of the join relations. The latter condition, called interesting order, can occur because an input to the join might be produced by an index scan of a tree-based index, another merge join, or some other plan operator that happens to produce output sorted on an appropriate key. Interesting orders need not be serendipitous: the optimizer may seek out this possibility and choose a plan that is suboptimal for a specific preceding operation if it yields an interesting order that one or more downstream nodes can exploit. Let's say that we have two relations and and . fits in pages memory and fits in pages memory. So, in the worst case sort-merge join will run in I/Os. In the case that and are not ordered the worst case time cost will contain additional terms of sorting time: , which equals (as linearithmic terms outweigh the linear terms, see Big O notation – Orders of common functions). (Wikipedia).
This is the first in a series of videos about the merge sort. It describes the principle of the merge sort algorithm, which takes a ‘divide and conquer’ approach to the problem of sorting and unordered list. The videos that follow build on these principles, leading towards a recursive im
From playlist Sorting Algorithms
Merge Sort Algorithm | Merge Sort Explained | Sorting Algorithms In Data Structures | Simplilearn
This video is based on the Merge Sort Algorithm. This tutorial on Merge Sort Algorithm Explained the fundamental steps and Procedures to be followed to design, develop, implement the Merge Sort Algorithm. Merge Sort Algorithm is one of the important Sorting Algorithm in Data Structures. Th
From playlist Data Structures & Algorithms [2022 Updated]
Merge Sort 4 – Towards an Implementation (Recursive Function)
This is the fourth in a series of videos about the merge sort. It includes a description of some pseudocode which combines into a single recursive function a helper program for splitting a list, and a helper program for merging a pair of ordered lists. This video describes how successive
From playlist Sorting Algorithms
Merge Sort 2 – Towards an Implementation (Split a List)
This is the second in a series of videos about the merge sort. It includes a description of an algorithm and pseudocode for taking an unordered list and splitting it into two separate unordered lists. The videos that follow build on these principles, leading towards a recursive implement
From playlist Sorting Algorithms
Merge Sort 3 – Towards an Implementation (Merge Two Lists)
This is the third in a series of videos about the merge sort. It includes a description of an algorithm and pseudocode for merging together two ordered lists into a single ordered list. The videos that follow build on these principles, leading towards a recursive implementation of a merg
From playlist Sorting Algorithms
From playlist Week 4 2015 Shorts
Searching and Sorting Algorithms (part 3 of 4)
Introductory coverage of basic searching and sorting algorithms, as well as a rudimentary overview of Big-O algorithm analysis. Part of a larger series teaching programming at http://codeschool.org
From playlist Searching and Sorting Algorithms
From playlist Algorithms 1
Merge, Join, Append, Concat - Pandas
“There should be one—and preferably only one—obvious way to do it,” — Zen of Python. I certainly wish that were the case with pandas. In reading the docs it feels like there are a thousand ways to do each operation. And it is hard to tell if they do the exact same thing or which one you
From playlist Python pandas — An Opinionated Guide
Lecture 15 | Programming Abstractions (Stanford)
Lecture 15 by Julie Zelenski for the Programming Abstractions Course (CS106B) in the Stanford Computer Science Department. Julie continues to cover sorting. She begins with an example of a selection sorting code and a graphic demo of the code in progress. Thereafter, she explains the d
From playlist Lecture Collection | Programming Abstractions
Paul Bendich (5/12/21): Data Complexes, Obstructions, Persistent Data Merging
Title: Data Complexes, Obstructions, Persistent Data Merging Abstract: Data complexes provide a mathematical foundation for semi-automated data-alignment tools that are common in commercial database software. We develop theory that shows that database JOIN operations are subject to genuin
From playlist AATRN 2021
Python pandas—Merge Exercises—Fictitious Names
Sometimes we learn best by doing. Unlike my other videos, I’ll be going through these exercises cold. Sometimes we’ll encounter ambiguous questions, and sometimes I'll be wrong. Learning from our mistakes can be a powerful teacher. So, it’s OK to be wrong now, because we’ll know how to avo
From playlist Python pandas -- Learning by doing
Live CEOing Ep 156: Database Integration in Wolfram Language
Watch Stephen Wolfram and teams of developers in a live, working, language design meeting. This episode is about Database Integration in the Wolfram Language.
From playlist Behind the Scenes in Real-Life Software Design
MSPTDA 07: Power Query: 6 Types of Joins, 6 Types of Merges: 9 Examples
Download Excel START Files: https://people.highline.edu/mgirvin/AllClasses/348/MSPTDA/Content/PowerQuery/007-MSPTDA-PowerQueryJoinsMergesStart.xlsx Download Excel FINISHED Files: https://people.highline.edu/mgirvin/AllClasses/348/MSPTDA/Content/PowerQuery/007-MSPTDA-PowerQueryJoinsMergesFi
From playlist Full Advanced Data Analysis & BI Class (MSPTDA). Power Query, Power Pivot, DAX, M Code, Power BI & Excel (30+ Videos)
Lecture 8: Data Structures and Algorithms - Richard Buckland
comp1927 lecture 8 data structures and algorithms richard buckland needs to do some exercise
From playlist CS2: Data Structures and Algorithms - Richard Buckland
Heap Sort - Intro to Algorithms
This video is part of an online course, Intro to Algorithms. Check out the course here: https://www.udacity.com/course/cs215.
From playlist Introduction to Algorithms
Annotation Output and Manipulation
Filmed during an in-person session of the Supercomputing for Everyone Series: De novo Assembly of Transcriptomes at Indiana University, 2018-2019. The complete workshop is free and open to the public compliments of the National Center for Genome Analysis Support (NCGAS). NCGAS is a manag
From playlist De novo Assembly of Transcriptomes
New Entity Query Functionality
To learn more about Wolfram Technology Conference, please visit: https://www.wolfram.com/events/technology-conference/ Speaker: Toni Schindler & Carlo Barbieri Wolfram developers and colleagues discussed the latest in innovative technologies for cloud computing, interactive deployment, m
From playlist Wolfram Technology Conference 2018
1 5 Merge Sort Motivation and Example 9 min
From playlist Algorithms 1
Parallel Query In PostgreSQL Robert Haas
I and others have been working on bringing parallel query for PostgreSQL for several years now, but PostgreSQL 9.6 is the first release expected to include a user-visible feature. And it's pretty cool. In this talk, I'll give an overview of the development of this feature, where we are now
From playlist 2016