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Recent questions tagged joins
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Joins in Relational Algebra (Self Doubt) while reading Elmasri Navathe
asked
Jan 10
in
Databases
by
shubhojit1412
(
5
points)
|
15
views
joins
natural-join
0
votes
1
answer
Self Doubt (Nested Loop Join)
Can someone please clarify why we keep the smaller loop outer and the bigger loop inner? (i.e. why do we select the relation with smaller number of tuples as the outer relation)
asked
Aug 16, 2020
in
Databases
by
Mellophi
(
363
points)
|
30
views
databases
nested-loop-join
joins
+1
vote
1
answer
GATE2012-50 Video Solution
Consider the following relations $A, B$ and $C:$ ... is the same as that of $A$. $(A\cup B)\bowtie _{A.Id > 40 \vee C.Id < 15} C$ $7$ $4$ $5$ $9$
asked
Apr 18, 2020
in
Databases
by
admin
(
569
points)
|
9
views
gate2012
databases
joins
normal
video-solution
0
votes
0
answers
GATE2004-14 Video Solution
Consider the following relation schema pertaining to a students database: Students (rollno, name, address) Enroll (rollno, courseno, coursename) where the primary keys are shown underlined. The number of tuples in the student and Enroll tables are $120$ and $8$ respectively. What ... (Student * Enroll), where *' denotes natural join? $8, 8$ $120, 8$ $960, 8$ $960, 120$
asked
Apr 18, 2020
in
Databases
by
admin
(
569
points)
|
20
views
gate2004
databases
easy
joins
natural-join
video-solution
0
votes
0
answers
GATE2014-2-30 Video Solution
Consider a join (relation algebra) between relations $r(R)$ and $s(S)$ using the nested loop method. There are 3 buffers each of size equal to disk block size, out of which one buffer is reserved for intermediate results. Assuming size(r(R))<size(s(S)) , the join ... $s(S)$ is more than 0.5. join selection factor between $r(R)$ and $s(S)$ is less than 0.5.
asked
Apr 18, 2020
in
Databases
by
admin
(
569
points)
|
10
views
gate2014-2
databases
normal
joins
video-solution
+1
vote
1
answer
GATE2005-IT-82b Video Solution
A database table $T_1$ has $2000$ records and occupies $80$ disk blocks. Another table $T_2$ has $400$ records and occupies $20$ disk blocks. These two tables have to be joined as per a specified join condition that needs to be evaluated for ... outer loop, the reduction in number of block accesses required for reading the data will be $0$ $30400$ $38400$ $798400$
asked
Apr 18, 2020
in
Databases
by
admin
(
569
points)
|
11
views
gate2005-it
databases
normal
joins
video-solution
0
votes
0
answers
GATE2007-IT-68 Video Solution
Consider the following relation schemas : b-Schema = (b-name, b-city, assets) a-Schema = (a-num, b-name, bal) d-Schema = (c-name, a-number) Let branch, account and depositor be respectively instances of the above schemas. Assume that account and ... depositor) Пc-name (σb-city = "Agra" branch ⋈ (σb-city = "Agra" ⋀ bal < 0 account ⋈ depositor))
asked
Apr 18, 2020
in
Databases
by
admin
(
569
points)
|
12
views
gate2007-it
databases
joins
relational-algebra
normal
video-solution
0
votes
0
answers
GATE2006-IT-14 Video Solution
Consider the relations r1(P, Q, R) and r2(R, S, T) with primary keys P and R respectively. The relation r1 contains 2000 tuples and r2 contains 2500 tuples. The maximum size of the join r1⋈ r2 is : 2000 2500 4500 5000
asked
Apr 18, 2020
in
Databases
by
admin
(
569
points)
|
7
views
gate2006-it
databases
joins
natural-join
normal
video-solution
0
votes
0
answers
GATE2005-IT-82a Video Solution
A database table $T_1$ has $2000$ records and occupies $80$ disk blocks. Another table $T_2$ has $400$ records and occupies $20$ disk blocks. These two tables have to be joined as per a specified join condition that needs to be evaluated for every ... be used in outer loop, the number of block accesses required for reading the data are $800000$ $40080$ $32020$ $100$
asked
Apr 18, 2020
in
Databases
by
admin
(
569
points)
|
11
views
gate2005-it
databases
normal
joins
video-solution
0
votes
0
answers
Self Doubt - Nested Loop Join (No. of Seeks)
What do you mean by Seek? For Natural Loop Join, we calculate No. of Seeks are (nr + br). Assume that, Relation r is called the Outer Relation and Relation s is called the Inner Relation. (ni,bj) – ni represents total no. of tuples and bj represents no. of blocks in that relation. Reference (Korth) – For Block Nested-Loop Join –
asked
Sep 10, 2019
in
Databases
by
ayushsomani
(
-1
points)
|
33
views
databases
joins
nested-loop-join
0
votes
0
answers
Doubts Regarding join algorithm
What is the number of block access in Indexed Nested Loop join & Sort-merge Join??? given, No. of blocks in relation R = $B_{r}$ No. of blocks in relation S = $B_{s}$ No. of records in relation i = $r_{i}$ Join is like R x S & size of R is less than size of S
asked
Jul 10, 2019
in
Databases
by
mrinmoyh
(
23
points)
|
12
views
databases
joins
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