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Recent questions tagged korth
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31
DBMS Korth Edition 4 Exercise 15 Question 11 (Page No. 589)
What is a recoverable schedule ? Why is recoverability of schedules desirable? Are there any circumstances under which it would be desirable to allow nonrecoverable schedules ? Explain your answer.
What is a recoverable schedule ? Why is recoverability of schedules desirable? Are there any circumstances under which it would be desirable to allow nonrecoverable sched...
akash.dinkar12
285
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akash.dinkar12
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Apr 1, 2019
Databases
korth
databases
transaction-and-concurrency
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32
DBMS Korth Edition 4 Exercise 15 Question 10 (Page No. 589)
Consider the precedence graph of Figure 15.18. Is the corresponding schedule conflict serializable ? Explain your answer.
Consider the precedence graph of Figure 15.18. Is the corresponding schedule conflict serializable ? Explain your answer.
akash.dinkar12
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akash.dinkar12
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Apr 1, 2019
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korth
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33
DBMS Korth Edition 4 Exercise 15 Question 9 (Page No. 589)
Since every conflict-serializable schedule is view serializable, why do we emphasize conflict serializability rather than view serializability?
Since every conflict-serializable schedule is view serializable, why do we emphasize conflict serializability rather than view serializability?
akash.dinkar12
813
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akash.dinkar12
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Apr 1, 2019
Databases
korth
databases
transaction-and-concurrency
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34
DBMS Korth Edition 4 Exercise 15 Question 8 (Page No. 589)
Consider the following two transactions: $T_1:$ $read(A);$ $read(B);$ $if A = 0$ $then$ $B := B + 1;$ $write(B);$ $T_2:$ $read(B);$ $read(A);$ $if B = 0$ $then$ $A := A + 1;$ ... $T_1$ and $T_2$ that produces a nonserializable schedule. $c$. Is there a concurrent execution of $T_1$ and $T_2$ that produces a serializable schedule ?
Consider the following two transactions:$T_1:$ $read(A);$ $read(B);$ $if A = 0$ $then$ $B := B + 1;$ $write(B);$$T_2:$ $read(B);$ ...
akash.dinkar12
331
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akash.dinkar12
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Apr 1, 2019
Databases
korth
databases
transaction-and-concurrency
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35
DBMS Korth Edition 4 Exercise 15 Question 7 (Page No. 589)
Explain the distinction between the terms $serial$ schedule and $serializable$ schedule.
Explain the distinction between the terms $serial$ schedule and $serializable$ schedule.
akash.dinkar12
189
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akash.dinkar12
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Apr 1, 2019
Databases
korth
databases
transaction-and-concurrency
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36
DBMS Korth Edition 4 Exercise 15 Question 6 (Page No. 589)
Justify the following statement: Concurrent execution of transactions is more important when data must be fetched from (slow) disk or when transactions are long, and is less important when data is in memory and transactions are very short.
Justify the following statement: Concurrent execution of transactions is more important when data must be fetched from (slow) disk or when transactions are long, and is l...
akash.dinkar12
709
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akash.dinkar12
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Apr 1, 2019
Databases
korth
databases
transaction-and-concurrency
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37
DBMS Korth Edition 4 Exercise 15 Question 5 (Page No. 588)
During its execution, a transaction passes through several states, until it finally commits or aborts. List all possible sequences of states through which a transaction may pass. Explain why each state transition may occur.
During its execution, a transaction passes through several states, until it finally commits or aborts. List all possible sequences of states through which a transaction m...
akash.dinkar12
2.6k
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akash.dinkar12
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Apr 1, 2019
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korth
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38
DBMS Korth Edition 4 Exercise 15 Question 4 (Page No. 588)
Database-system implementers have paid much more attention to the ACID properties than have file-system implementers. Why might this be the case ?
Database-system implementers have paid much more attention to the ACID properties than have file-system implementers. Why might this be the case ?
akash.dinkar12
853
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akash.dinkar12
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Apr 1, 2019
Databases
korth
databases
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39
DBMS Korth Edition 4 Exercise 15 Question 3 (Page No. 588)
Consider a file system such as the one on your favorite operating system. a. What are the steps involved in creation and deletion of files, and in writing data to a file ? b. Explain how the issues of atomicity and durability are relevant to the creation and deletion of files, and to writing data to files.
Consider a file system such as the one on your favorite operating system.a. What are the steps involved in creation and deletion of files, and in writing data to a file ?...
akash.dinkar12
407
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akash.dinkar12
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Apr 1, 2019
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korth
databases
transaction-and-concurrency
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40
DBMS Korth Edition 4 Exercise 15 Question 2 (Page No. 588)
Suppose that there is a database system that never fails. Is a recovery manager required for this system ?
Suppose that there is a database system that never fails. Is a recovery manager required for this system ?
akash.dinkar12
338
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akash.dinkar12
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Apr 1, 2019
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41
DBMS Korth Edition 4 Exercise 15 Question 1 (Page No. 588)
List the $ACID$ properties. Explain the usefulness of each.
List the $ACID$ properties. Explain the usefulness of each.
akash.dinkar12
283
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akash.dinkar12
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Apr 1, 2019
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42
DBMS Korth Edition 4 Exercise 11 Question 20 (Page No. 491)
How does data encryption affect index schemes ? In particular, how might it affect schemes that attempt to store data in sorted order ?
How does data encryption affect index schemes ? In particular, how might it affect schemes that attempt to store data in sorted order ?
akash.dinkar12
283
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akash.dinkar12
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Apr 1, 2019
Databases
korth
databases
hashing
descriptive
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43
DBMS Korth Edition 4 Exercise 12 Question 16 (Page No. 491)
Why is a hash structure not the best choice for a search key on which range queries are likely ?
Why is a hash structure not the best choice for a search key on which range queries are likely ?
akash.dinkar12
1.6k
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akash.dinkar12
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Apr 1, 2019
Databases
korth
databases
hashing
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1
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44
DBMS Korth Edition 4 Exercise 12 Question 12 (Page No. 490)
Suppose that we are using extendable hashing on a file that contains records with the following search-key values: $2, 3, 5, 7, 11, 17, 19, 23, 29, 31$ Show the extendable hash structure for this file if the hash function is $h(x)$ $=$ $x$ $mod$ $8$ and buckets can hold three records.
Suppose that we are using extendable hashing on a file that contains records with the following search-key values:$2, 3, 5, 7, 11, 17, 19, 23, 29, 31$Show the extendable ...
akash.dinkar12
2.4k
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akash.dinkar12
asked
Apr 1, 2019
Databases
korth
databases
hashing
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45
DBMS Korth Edition 4 Exercise 12 Question 11 (Page No. 491)
What are the causes of bucket overflow in a hash file organization ? What can be done to reduce the occurrence of bucket overflows ?
What are the causes of bucket overflow in a hash file organization ? What can be done to reduce the occurrence of bucket overflows ?
akash.dinkar12
636
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akash.dinkar12
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Apr 1, 2019
Databases
korth
databases
hashing
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0
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46
DBMS Korth Edition 4 Exercise 12 Question 10 (Page No. 491)
Explain the distinction between closed and open hashing. Discuss the relative merits of each technique in database applications.
Explain the distinction between closed and open hashing. Discuss the relative merits of each technique in database applications.
akash.dinkar12
1.1k
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akash.dinkar12
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Apr 1, 2019
Databases
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databases
hashing
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47
DBMS Korth Edition 4 Exercise 12 Question 5 (Page No. 490)
Construct a $B^+$-tree for the following set of key values: $(2, 3, 5, 7, 11, 17, 19, 23, 29, 31)$ Assume that the tree is initially empty and values are added in ascending order. Construct B+-trees for the cases where the number of pointers that will fit in one node is as follows: a. Four b. Six c. Eight
Construct a $B^+$-tree for the following set of key values:$(2, 3, 5, 7, 11, 17, 19, 23, 29, 31)$Assume that the tree is initially empty and values are added in ascending...
akash.dinkar12
1.5k
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akash.dinkar12
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Apr 1, 2019
Databases
korth
databases
indexing
b-tree
descriptive
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4
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48
DBMS Korth Edition 4 Exercise 12 Question 4 (Page No. 489)
Is it possible in general to have two primary indices on the same relation for different search keys ? Explain your answer.
Is it possible in general to have two primary indices on the same relation for different search keys ? Explain your answer.
akash.dinkar12
1.4k
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akash.dinkar12
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Apr 1, 2019
Databases
korth
databases
indexing
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49
DBMS Korth Edition 4 Exercise 12 Question 3 (Page No. 489)
What is the difference between a primary index and a secondary index ?
What is the difference between a primary index and a secondary index ?
akash.dinkar12
322
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akash.dinkar12
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Apr 1, 2019
Databases
korth
databases
indexing
descriptive
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50
DBMS Korth Edition 4 Exercise 12 Question 2 (Page No. 489)
Since indices speed query processing, why might they not be kept on several search keys ? List as many reasons as possible.
Since indices speed query processing, why might they not be kept on several search keys ? List as many reasons as possible.
akash.dinkar12
311
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akash.dinkar12
asked
Apr 1, 2019
Databases
korth
databases
indexing
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51
DBMS Korth Edition 4 Exercise 12 Question 1 (Page No. 489)
When is it preferable to use a dense index rather than a sparse index ? Explain your answer.
When is it preferable to use a dense index rather than a sparse index ? Explain your answer.
akash.dinkar12
252
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akash.dinkar12
asked
Apr 1, 2019
Databases
korth
databases
indexing
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DBMS Korth Edition 4 Exercise 11 Question 18 (Page No. 442)
Consider a relational database with two relations: $course (course-name, room, instructor)$ $enrollment (course-name, student-name, grade)$ Define instances of these relations for three courses, each of which enrolls five students. Give a file structure of these relations that uses clustering.
Consider a relational database with two relations:$course (course-name, room, instructor)$$enrollment (course-name, student-name, grade)$Define instances of these relatio...
akash.dinkar12
301
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akash.dinkar12
asked
Apr 1, 2019
Databases
korth
databases
file-organization
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53
DBMS Korth Edition 4 Exercise 11 Question 17 (Page No. 442)
List two advantages and two disadvantages of each of the following strategies for storing a relational database: $a$. Store each relation in one file. $b$. Store multiple relations (perhaps even the entire database) in one file.
List two advantages and two disadvantages of each of the following strategies for storing a relational database:$a$. Store each relation in one file.$b$. Store multiple r...
akash.dinkar12
270
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akash.dinkar12
asked
Apr 1, 2019
Databases
korth
databases
file-organization
descriptive
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54
DBMS Korth Edition 4 Exercise 11 Question 16 (Page No. 442)
In the sequential file organization, why is an overflow block used even if there is, at the moment, only one overflow record ?
In the sequential file organization, why is an overflow block used even if there is, at the moment, only one overflow record ?
akash.dinkar12
169
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akash.dinkar12
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Apr 1, 2019
Databases
korth
databases
file-organization
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55
DBMS Korth Edition 4 Exercise 11 Question 14 (Page No. 442)
Explain why the allocation of records to blocks affects database-system performance significantly.
Explain why the allocation of records to blocks affects database-system performance significantly.
akash.dinkar12
176
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akash.dinkar12
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Apr 1, 2019
Databases
korth
databases
file-organization
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56
DBMS Korth Edition 4 Exercise 11 Question 10 (Page No. 441)
Give an example of a database application in which the pointer method of representing variable-length records is preferable to the reserved-space method.Explain your answer.
Give an example of a database application in which the pointer method of representing variable-length records is preferable to the reserved-space method.Explain your answ...
akash.dinkar12
192
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akash.dinkar12
asked
Apr 1, 2019
Databases
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databases
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57
DBMS Korth Edition 4 Exercise 11 Question 9 (Page No. 441)
Give an example of a database application in which the reserved-space method of representing variable-length records is preferable to the pointer method. Explain your answer.
Give an example of a database application in which the reserved-space method of representing variable-length records is preferable to the pointer method. Explain your ans...
akash.dinkar12
126
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akash.dinkar12
asked
Apr 1, 2019
Databases
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databases
file-organization
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58
DBMS Korth Edition 4 Exercise 11 Question 2 (Page No. 440)
How does the remapping of bad sectors by disk controllers affect data-retrieval rates ?
How does the remapping of bad sectors by disk controllers affect data-retrieval rates ?
akash.dinkar12
254
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akash.dinkar12
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Apr 1, 2019
Databases
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databases
file-organization
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59
DBMS Korth Edition 4 Exercise 11 Question 1 (Page No. 440)
List the physical storage media available on the computers you use routinely.Give the speed with which data can be accessed on each medium.
List the physical storage media available on the computers you use routinely.Give the speed with which data can be accessed on each medium.
akash.dinkar12
263
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akash.dinkar12
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Apr 1, 2019
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60
SQL QUERY
shivanisrivarshini
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shivanisrivarshini
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May 16, 2016
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