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0
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1answer
68 views

Why isn't there a universal separator character for data files? [closed]

I am not sure if this is the correct forum for this question, but... After so much time and usage of spreadsheets and data files in general, there is a need to cater for all types of files containing ...
0
votes
0answers
28 views

Pointers to schema evolution and semi-automated instance migration

QUESTION EDITED Since this question wasn't clear, I'll rephrase. See question-history for original. I'm looking for academic papers that describe schema evolution on documents (1) in a generic way. ...
0
votes
1answer
21 views

How can I solve this Functional Dependency?

Consider R(A, B, C) with FDs F ={A→B, B→C, A→C} Prove or disprove F |= C → A There are 7 inference rules from Armstrong's Axiom. Which one is to use here?
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0answers
10 views

Question about 3NF Form

So I was given set of productions and have ocmputed minimal cover. However, I have to change the set to 3NF form. I know that a production(X->A) is in 3NF form if one of these statements is true: ...
0
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0answers
37 views

2 phase locking with added increment mode

Suppose that a DBMS recognizes increment as an atomic operation, in addition to the read and ...
3
votes
2answers
54 views

The finer details of Meek's STV

Meek's version of the Single Transferable Vote system [.pdf] is used in multiple big elections including those of New Zealand and Stack Exchange. Demonstration (with thanks to the Department of ...
1
vote
0answers
655 views

Difference between conflict serializability and view serializability

In my understanding both of them can be converted to serial schedules. (This helps with consistency by isolation property while also giving the performance boost by concurrency). I'm unable to ...
2
votes
0answers
36 views

Using cross-products with relational algebra

I have some questions about something that I'm working on in an assignment for my database class. Here is the schema for the questions I'm working on, so that you know what to refer to: ...
0
votes
1answer
80 views

A schedule is not conflict-serializable. Is it serializable?

While reading this solved quiz on concurrency control, I got stuck on exercise 2, which reads as follows: 2) Consider the following schedule: S: r1(X), w2(X), r3(X), r1(Y), w2(Z), r3(Y), ...
-3
votes
2answers
39 views

An application where we always delete the oldest object? [closed]

In what king of application, in which we insert or delete objects, we always delete the oldest one (the least recently stored, more precisely which was the first object stored) ?
9
votes
2answers
135 views

Good snapshottable data structure for an in-memory index

I'm designing an in-memory object database for a very specific use case. It is single writer, but must support efficient concurrent reads. Reads must be isolated. There is no query language, the ...
1
vote
1answer
58 views

Data versioning in a relational database

I've been working on an industrial project where my job was to design a data model in-memory and in a relational database in such a way, that can capture the time-varying nature of the production ...
5
votes
1answer
278 views

How to find a basis which is guaranteed to need 9 or less characters to represent a 12 digits number?

I'm trying to map a 12 digit number into a fixed width file. For a number of reasons, it must be compressed in such a way that it is guaranteed to be less than or equal to 9 characters (alpha numeric ...
3
votes
1answer
61 views

Algorithm for automatic/optimal database joins?

I'm curious if there is existing literature or well known algorithms out there for a problem I am working on. Given a normalized relational database with valid foreign key constraints and a list of ...
5
votes
1answer
362 views

A relational algebra extended to model the full DML (“CRUD”) domain

There are multiple references about the relational algebra for modeling queries (SELECT) but I have found very very little on the expanded algebra that would ...
2
votes
0answers
27 views

How to store linguistic data?

I'm both interested in practical and theoretical aspects of the problem. How do you store linguistic data. Suppose you have stemmed, parsed, tagged and, perhaps even did some preliminary analysis, ...
0
votes
1answer
61 views

Database normalization impractical

After third form normalization, extra tables shall be created. And the functional determinant are used as primary key in the new table, as foreign key in the modified old table. My question is that ...
0
votes
1answer
913 views

What is the difference between a prime attribute and a proper subset of the candidate key? [closed]

I am taking DBMS classes and am currently studying the various normal forms. The following is the definition of a Prime Attribute I learned in class: ...
1
vote
0answers
68 views

two phase locking and a contest question?

In 2PL (two phase locking), what advantage(s) does the rigorous model have over the strict model? I) There is no advantage over the strict model. II) In contrast to the strict model, it ...
0
votes
1answer
38 views

How can I formalize key value stores with set theory?

I'm currently developing a simple key-value NoSQL store and want to build its formal model. I found article about key value formalisation with category theory, but I'm interested are there some works ...
3
votes
2answers
149 views

Linearizability and Serializability in context of Software Transactional Memory

I've been trying to grasp serializability and linearizability in the context of software transactional memory. However, I think both notions can be applied to transactional memory in general. At this ...
3
votes
0answers
97 views

How to generate globally unique timestamps for transactions in distributed database systems?

According the paper [1] (Section 4), timestamp ordering (T/O) is a technique whereby a serialization order is selected a priori and transaction execution is forced to obey this order. In the ...
0
votes
1answer
81 views

Information Systems (IS) and Data Warehouse

I'm working on a research project about the adoption of DWH systems and doing some literature review I find many documents that refer to Information System. I tried to find the right definition of ...
2
votes
0answers
102 views

Rollback and Timestamp Ordering in Database

If we use the Timestamp Ordering for concurrency control in following scheduling: My TA says T2,T3,T5 is Run and T4,T5 is Rollback. I think it's false. any expert could help us?
4
votes
1answer
64 views

n closest points in a set of lat/long coordinates

Here's my problem: I have a website where people can search based on their location (which is converted to lat/long coordinates). I have many products stored in a database with their lat/long ...
-1
votes
0answers
52 views

Could there be an end of (human-organized) databases? [closed]

I'm not a computer science guy but just curious about a potential decline of databases. I believe there will always be data, that's for sure, but would there always be databases? Databases are a ...
0
votes
1answer
36 views

Terminology for describing a kind of server [closed]

What is the adjective used to describe the fact that a server keep track of queries made by a user. I take the example of a database server.
2
votes
2answers
234 views

When should you use the existential and universal quantifiers for Relational Calculus?

Could someone explain to me WHEN do you use existential and universal quantifiers for Relational Calculus? Given this schema: Hotel(hotelNo, hotelName, city) ...
3
votes
1answer
336 views

Can a schedule with cyclic precedence graph still be serialisable?

We know Every conflict serializable schedule is serializable, but not all serializable schedules conflict-serializable. (*) so it means there is at least one serializable schedule that not conflict ...
1
vote
0answers
32 views

1-serializability theorem in database theory

In the paper "MVCC@TODS'1983 by Bernstein et al.", 1-serializability ($1$-$\text{SR}$) problem is defined as a decision problem: To decide whether an MV (multi-version) log $L$ is $1$-$\text{SR}$. ...
1
vote
1answer
89 views

A relationship in a UML class diagram

I am investigating a small database in a paper: Each line is a selling record. For instance, Line 2 expresses that ...
2
votes
1answer
77 views

What actually is the concept of transparency? Why not call it Abstraction?

I searched this over Google few times but ended up with articles on transparency rather than an answer. With relation to distributed database study(or distributed OS), what is the concept of ...
0
votes
1answer
154 views

Automatically generate meaningful queries for a data table

My field of research is not Database or AI. But I have some problems to solve, and would like to know which branch this kind of problems belong to, and what are the results. The main question is: ...
1
vote
2answers
497 views

B-Tree and how it is used in practice

I understand what a B-Tree is (I already implemented a B-Tree in Java with insert and delete methods that preserve the invariant). However I do not understand exactly how it is used for example for ...
3
votes
1answer
4k views

Difference between data duplication and data redundancy

My Computing teachers talk about data duplication and data redundancy in terms of databases as different things, but I'm struggling to differentiate them. The context is database normalisation, and in ...
1
vote
1answer
48 views

Partial Range Query on Inverted File with Combined Index

I am currently reading Multidimensional and Metric Data Structures by Hanan Samet for fun. The combined index is discussed on page 5-6. I do understand it in the sense that the inverted file itself is ...
0
votes
2answers
28 views

Determine Epsilon for identification [closed]

I have a project in which I need to compare different distances in a database with a distance in input in order to identify a person. For that I use this expression: DistanceDB - DistanceInput < ...
2
votes
1answer
83 views

Does “serializable” also mean that it's lockable

Here's an final exam question for a Database Fundamentals class. I've read the book, stuff online.. I can't figure out if "serializable" also means that the schedule is ...
0
votes
1answer
90 views

Functional dependencies with the same key?

let's consider a table with carID | hireDate | manufactory | model | custID | custName | outletNo | outletLoc I want to evaluate all the functional dependencies ...
1
vote
0answers
56 views

Relational calculus: what is a range-restricted variable?

I know that if the set of free variables for a relational calculus query is equal to the set of range-restricted variables then the query is (roughly) safe. I also can identify free variables. ...
1
vote
0answers
19 views

In search for toy relations to test relational algebra

Does anybody know any toy database / relations that are particularly good and also complete to demonstrate and test relational algebra concepts? I'm hoping some database researchers should have ...
0
votes
5answers
541 views

What is the best way to index lookups on a 2D array of integers that is boundless in x and y?

Lets say you have a data model that consists of a 2D grid of integer points. This grid is sparsely populated and boundless in x and y (up to the max of a 32-bit integer). What is the best way to ...
1
vote
0answers
28 views

How to display distinct rows from single column without using DISTINCT keyword and count() function? [closed]

How to display distinct rows from single column without using DISTINCT keyword and [having count(*) > 1 ] ? My question is can we do this using sub-queries or co-related sub query ? If yes how we can ...
0
votes
1answer
728 views

Resolving many to many relationships?

I'm trying to separate a weird relationship. It goes like this: One waiter can serve more than one kind of drink and one kind of drink can be served by more than one waiter. One waiter can wear more ...
2
votes
0answers
40 views

The research area of data exchange format,i.e. the format that stores serialized objects [closed]

As we know, if we want to design and implement a programming language like JAVA, C++ and C language, we will reference the compilation theory. Similarly, if we would like to design and implement a ...
-2
votes
1answer
485 views

Number of concurrent schedules in database

In a database system, say there are $N$ transactions each having $m_1,m_2,\dots,m_N$ operations. How many concurrent schedules are possible? $(m_1+m_2+....+m_n)!$ is the number of possible ...
0
votes
1answer
36 views

result after applying on delete cascade

In this table B is foreign key referring to the primary key A with on delete cascade option.What will be the result after deleting (4,3) and how A:1 4 2 9 3 5 B:3 3 4 2 9 4
0
votes
1answer
152 views

E-R diagram and relationships

Suppose we have two entities $A$ and $B$ and some relationship between them. If there is an $M:N$ relationship between them (i.e. an $M$ on the line connecting $A$ to the relationship and an $N$ ...
8
votes
2answers
2k views

Who needs linearizability?

I've been reading about the differences between serializability and linearizability, which are both consistency criteria for replicated systems such as replicated databases. However, I don't know in ...
2
votes
1answer
479 views

Find similar vector by Locality Sensitive Hashing

I have many vectors in my database. They are in high dimensions such as: $v_1$ : $\langle 23, 23, 1, 33, 103, 219, \dots \rangle$ $v_2$ : $\langle 92, 83, 1, 33, 239, 192, \dots \rangle$ ... I ...