Database Transactions – Part 3 Concurrent Transactions Concurrent Transactions Interleaved processing: transactions are interleaved in a single CPU. T 3 T 1 Time T 2 T 2 T 1 Data Concurrent Transactions Parallel processing: transactions are executed in parallel in multiple CPUs. T3 T1 Time T2 T2 T1 Data T3 T1 Time T2 Data Concurrent […]
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Database Transactions – Part 2 ACID Properties ACID Properties DBMSs ensure the following properties of transactions. Atomicity: The execution of each transaction is atomic, i.e., either all operations are completed or not done at all. Consistency: The states of a database are consistent (w.r.t. defined business rules) before and after each transaction. Isolation: Execution results
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SQL – Part 1 SQL and Data Definition Language What is SQL? SQL stands for Structured Query Language SQL was initially developed at IBM (SEQUEL → SQL), as one of the first commercial languages for the relational data model. 1986 – SQL was standardised by ANSI and ISO ( SQL-86). 1989 – SQL was revised
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COMP2400/6240 – Relational Databases SQL Sample Questions Due date: TBD Question 1 Unknown Marks The relational database moviedb has the following database schema: Movie(title, production year, country, run time, major genre) primary key : {title, production year} Person(id, first name, last name, year born) primary key : {id} Award(award name, institution, country) primary key :
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1/59 Week 8 Workshop – Query Processing and Optimisation 2/59 Housekeeping 1 Assignment 2 (Database Theory) for both COMP2400/6240 students: The submission deadline is 23:59, Oct 12, 2021. This assignment must be done individually (no group work). Please join the special drop-in sessions if you need any clarifications. 2 All the labs on Oct 4
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Entity-Relationship Model – Part 4 From ER to Relations Recap – Data Modeling Requirements ER diagram Relational database schema Relational DBMS Conceptual level Logical level Physical level ER design is subjective: There are many ways to model a given scenario. Analyzing alternative schemas is important. Constraints play an important role in designing a good database.
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Relational Algebra (Part 1) Two Questions 1 What is the difference between procedural and declarative languages? 2 What is the foundation for relational query languages like SQL? Why Relational Algebra? SQL is a (fairly) declarative query language: SQL queries describe the set of tuples you want to get. To be efficiently implemented, SQL queries need
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9/1/2021 1 Introduction to Data Science Lecture 4 Semi-Structured Data, XML CIS 5930/4930 – Fall 2021 Exam • One Midterm exam – Proctored, online (Canvas) – November 3 during regular scheduled lecture time • 3.05 – 4.20pm EST – To be done individually – Multiple choice test – Closed book, notes – A week before
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1/50 Week 6 Workshop – Normalisation http://en.wikipedia.org/wiki/Ursus_Wehrli http://en.wikipedia.org/wiki/Ursus_Wehrli 2/50 Housekeeping Assignment 1 (SQL) (due 11:59pm, 3 Sep 2021) The mark and feedback will be released on 17 Sep 2021. An optional exercise website for our course https://cs.anu.edu.au/dab/bench/db-exercises/ An anonymous survey from our course representatives on Wattle (till 4 Sep under Week 6) Help us to
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1/56 Week 9 Workshop – Database Security 2/56 Qing Wang Website: http:// users.cecs.anu.edu.au/∼u5170295/ https:// graphlabanu.github.io/ website/ Zoom drop-in session: Tuesday 2pm-3pm (Week 10 to Week 12) Research areas: Data management and analytics Data mining Deep learning on graphs Graph algorithms. http://users.cecs.anu.edu.au/~u5170295/ https://graphlabanu.github.io/website/ 3/56 House Keeping Lab 8 (Database programming) in Week 10 is optional –