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Any elegant approach to search where users have permissions on subset of records?

I work in Search and have seen following problem appear in different forms. There are many users in an enterprise; they have ability to create records. Each user has variable level of access to some ...
Asad Iqbal's user avatar
2 votes
0 answers
32 views

How can we reduce the spatial complexity of intermediate indexes in relational databases at execution time?

In relational databases, what are the practical or theoretical ways to reduce the size and spatial complexity of intermediate indexes or tables* at execution time (so for example to reduce the size of ...
Heiz's user avatar
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Primary File Organization in DBMS - Files of ordered records (sorted files)

"Fundamental of Database Systems", 3rd ed. by Elmasri and Navathe, page 136 says: "We can physically order the records of a file on disk based on the values of one of their fields [...]&...
GuestUser's user avatar
2 votes
0 answers
92 views

Database Access Cost Estimate - Linear Search over non-key attribute

How does one estimate the access cost for the below query given that the data is sorted according to a non-key attribute, that the data is not uniformly distributed across all possible values of said ...
Scb's user avatar
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Why don't RDBMS use a quorum based solution to do failover

For RDBMS viz. MySql, PostgreSql a common solution for scalability and high availability is to run a primary instance as master that is a read-write instance and one or more read replicas. If the ...
Saptarshi Basu's user avatar
2 votes
0 answers
266 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: ...
Dan Czarnecki's user avatar
2 votes
0 answers
63 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, ...
wvxvw's user avatar
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2 votes
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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. However,...
false_azure's user avatar
2 votes
0 answers
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Algorithm for query comparison

Lets say I have a global dataset and I run queries over those data set. For example my dataset would be #id, #Name, #Employee, #Birthdate, #number_of_children 1, Nick, Nasa, 1982, 1 2, Jack, Exon, ...
yilmazhuseyin's user avatar
1 vote
0 answers
36 views

Relational calculus: "Find all X with at least y amount of Z"

Assuming I have two relations: Supplier [ID (PK), Name, City, Country] and Item [ID (PK), Name, Department, Price, Stock, Supplier_ID (FK)] What would be the easiest way to determine the following ...
T.E.'s user avatar
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1 vote
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Advantages to create Male and Female entities separate from User rather than making gender a property in a database?

The screenshot is from Georgia Tech's CS-6400. The instructor was talking about inheritance of Sub-Types and Super-Types. My question is, why are Male and ...
Erin's user avatar
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1 vote
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First normal form

I am confused about an aspect of the definition of first normal form in relational database model. Codd 1970 ("A Relational Model of Data for Large Shared Data Banks") defines normalization (...
JacquesB's user avatar
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constant relation in the base case of relational algebra

in the base case of the inductive definition of the operations of the relational algebra there is also the so called "constant relation" (as for example found in the definition here https://...
sorry's user avatar
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1 vote
0 answers
38 views

Which of the query approaches are more efficient?

There are two relations, registered(participant,topic) and fee(participant,amount). The primary key for registered is (participant, topic) and the primary key for fee is participant. The premise is ...
Swarnabja Bhaumik's user avatar
1 vote
0 answers
35 views

Is Neo4J computationally equivalent to relational algebra

I am wondering whether Neo4j and the associated Cypher query language is computationally equivalent to relational algebra? Any ideas or papers on that topic?
dan b's user avatar
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What does mean by the independent columns in 4NF normalization?

For a table to satisfy the Fourth Normal Form, it should satisfy the following two conditions: It should be in the Boyce-Codd Normal Form. And, the table should not have any Multi-valued Dependency. ...
A Paul's user avatar
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112 views

In index allocation scheme, what parameters does the maximum size of a file depends on?

My understanding is as follows: ...
Tushar Bhatt's user avatar
1 vote
0 answers
51 views

What does the three schema architecture of DBMS refer to?

This architecture contains three layers or levels of the database management system: External level Conceptual level Internal level Can some one explain to me with a practical real example so that ...
smraj's user avatar
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1 vote
0 answers
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Number of tables required to decompose a function into BCNF

I know this is not a question answer posting site, but for sake of explaining my doubt I will like to post a question Say you are given table like R(A,B,C,D,E,F)= {AB→C, BC → A, AC→ B , B → D , D→...
Turing101's user avatar
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1 vote
0 answers
388 views

Using relational algebra to express all with a condition

I encountered this question while revising for my finals exam on database theory. The following database contains information about car repair workshops. The following tables are used: $$Workshop(\...
Iwan Widargo's user avatar
1 vote
0 answers
70 views

How do I implement fixed block storage file system in database from typical file-level file system?

I've a typical parent ID based file system in database and files are physically stored on disks. What I want is to store files in blocks (4096K) of fixed size. Chunking can be used I found, but how ...
Abhigyan Tiwari's user avatar
1 vote
0 answers
61 views

Understanding connection between different database concurrency control protocol

I have came across following diagram related to timestamp based concurrency control protocols in database systems: I don't know whether its correct or not. As per my interpretation, it means all ...
RajS's user avatar
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1 vote
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134 views

Understanding validation based database concurrency control protocol

Database book by Korth explains validation protocol as follows : To perform the validation test, we need to know when the various phases of transactions took place. We shall, therefore, associate ...
RajS's user avatar
  • 1,677
1 vote
1 answer
380 views

Is my decomposition of R into 3NF is lossless and preserving all dependencies?

I have a schema R = {A,B,C,D,E} and the set F of FDs: F = {A --> BCDE, CD --> E, EC --> B}. Candidate key = A Non - Prime Attributes = BCDE Prime Attributes = A According to me, there is no partial ...
Aamir Nawab's user avatar
1 vote
0 answers
55 views

Merge unstructured with structured data

We have a database with well-formated and structured data. From time to time we get Excel - files from our clients. This Excel Files have to be imported to the database. It it very important that we ...
OPunktSchmidt's user avatar
1 vote
0 answers
814 views

Question regarding ER Diagram design

I'm working through a Database Design textbook, and one of the problems involving ER Diagram design is giving me some trouble. The diagram is for a UNIVERSITY database with the following rules: 1) ...
enharmonics's user avatar
1 vote
0 answers
68 views

Need help with functional dependencies (Database Theory)

I'm trying to understand functional dependencies in databases. Let's say, there are 3 tuples in an instance of a certain relation S as shown below. I'm trying to determine if a certain functional ...
El Dj's user avatar
  • 151
1 vote
0 answers
53 views

Advantages of using a RDBMS

Apologies if this isn't the correct forum but I thought it would be too academic for the DBA forum. In my work I'm looking to research some of the benefits of using an RDBMS product over traditional ...
user5495269's user avatar
1 vote
0 answers
236 views

Finding smallest canonical cover from given set of functional dependencies

I did not find any book discussing this but I came across the problem. The given set of FD was: $F=\{B\rightarrow A,D\rightarrow AC,B\rightarrow C,AB\rightarrow D,BC\rightarrow D\}$ Surprisingly the ...
Mahesha999's user avatar
  • 1,763
1 vote
1 answer
251 views

Lookup complexity in B-trees [Database]

Given that: B = n/R blocks in the file 2d index records per block (blocking factor): 2d > R an extra block access from the index to the datafile I am not able ...
letsBeePolite's user avatar
1 vote
0 answers
7k 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 ...
aste123's user avatar
  • 445
1 vote
0 answers
117 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 ...
M. holi's user avatar
  • 139
1 vote
0 answers
78 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 $1$-$\text{SR}$. ...
hengxin's user avatar
  • 9,561
1 vote
0 answers
27 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 ...
qazwsx's user avatar
  • 131
0 votes
0 answers
8 views

How can I optimize the performance of a large React application with multiple state updates?

I'm working on a large React application that has several components with frequent state updates. I've noticed that the performance is starting to degrade, especially when there are multiple ...
Salman Mehmood's user avatar
0 votes
0 answers
13 views

Datastore supporting TTL with range queries

We have a data access pattern in which we need to get users added in the time range say timestamp-1 to timestamp-2 and we don't want to keep older data say max 1 day, so DB should have an inbuilt ...
tusharRawat's user avatar
0 votes
0 answers
8 views

Can a candidate key for a composite attribute be called a composite key?

Let's take an example of student entity type Name Class Section Address (Line1, Line2, City, State, Country, PinCode) Since composite attribute holds multiple atomic attributes, such that the group ...
tbhaxor's user avatar
  • 208
0 votes
0 answers
46 views

Sensibility analysis for a discrete output data

I have a dataset with 1055 samples and 168 features. I want to remove some features in order to train a model on my dataset. The model should output a binary field (either 0 or 1 that is known). Some ...
mle's user avatar
  • 101
0 votes
0 answers
11 views

How can I anonymize/ de-identify clinical data present in tabular format

So I have been tasked to anonymize clinical data that..most of the time would be present in the form of tables. I've looked into algorithms like generalization,redaction,K-anonymity, l-diversity,t-...
S1000's user avatar
  • 1
0 votes
0 answers
25 views

How does waiting 7ms and atomic clock help GCP spanner create external consistency?

My understanding why distributed transaction need synchronized clock is the following Assume NTP max drift is 250ms ...
olaf's user avatar
  • 101
0 votes
0 answers
49 views

The Green500 ranks supercomputer energy efficiency. Is there such a ranking of energy efficiency for data centers?

The Green500 is a biannual ranking of the world's most energy-efficient supercomputers. It was first measured in millions of floating-point operations per second per watt of power consumed, and is now ...
KEY_ABRADE's user avatar
0 votes
0 answers
61 views

Help understand Z order curve range searching

After "speaking" with ChatGPT, I decided to test Z Order Curve. The code interleaves 2D data, then search for range x: [2..4], y: [2..4] Programming code using C/C++ should be as follows: <...
Nick's user avatar
  • 105
0 votes
0 answers
19 views

How can Amazon Aurora gain higher read-only throughput?

I read the Amazon Aurora paper and in the performance result section (i.e. 6.1.1), it says The results are shown in Figure 7 and Figure 6, and measure the performance in terms of write and read ...
hikky36's user avatar
  • 101
0 votes
0 answers
32 views

Lock upgradation in Two Phase Locking

Is lock conversion (upgradation) from $Shared$ to $Exclusive$ allowed in Basic Conservative Strict Rigorous types of 2PL techniques. Following is an example of disallowed attempt of lock conversion ...
Ajit Kumar's user avatar
0 votes
0 answers
11 views

In SSTables, why is it possible to group records and compress them?

I am currently reading 'Designing Data Intensive Applications' by Kleppman. In the SSTables and LSM Trees section, it is mentioned that one of the advantage of SSTables is: "Since read requests ...
Udeshya D.'s user avatar
0 votes
0 answers
17 views

This diagram serves to determine the components of a data entry in my database. What is the name of this type of diagram?

To properly insert a data entry in my database, I have to reach the last box in this diagram. A box represents either a flag or a data structure that participates in determining a single entry. What ...
shintuku's user avatar
  • 101
0 votes
0 answers
47 views

Is there an algorithm for finding rows that have same sum of column values up to a threshold value?

I have a table like this (more specifically a nested dictionary) img a b c d e img1 0 0 1 0 1 img2 3 1 0 0 2 img3 4 0 0 0 1 img4 2 2 0 0 0 img5 0 0 0 0 2 img6 2 2 0 0 0 img7 1 0 0 1 0 img8 0 ...
Jeni's user avatar
  • 1
0 votes
0 answers
88 views

Is there a sorting program or formula to sort and place individuals in classes based on preferences

I am looking for a formula or program to help place people in classes based on their preferences. The elements of the problem are: There are 30 class choices a student can pick from. There are 400 ...
Nick B. 's user avatar
0 votes
1 answer
82 views

Check whether a decomposition is in 3nf

In a database systems course, we have been presented with the following definition for third normal form (3NF): A relation $R$ is in 3NF means: a nontrivial dependency $A_1,\dots,A_n\to B_1,\dots B_m$...
MiddleEasternPrince's user avatar
0 votes
0 answers
25 views

Implement this as Attribute or Entity Set?

I am creating a database on students' interests using the Entity-Relationship Model for a University assignment. Should I implement the circled stuff as attribute, or an entity set?
Suchet Saxena's user avatar