unit 5+6: query processing + Transactions Mang.

Question 1

what topics are included in this unit

Answer 1

1. query processing problem
2. objectives of query processing
3. complexities of relational algebra operations
4. characterization of query processing
5. layers of query processing
6. brief introduction of each layer of query processing

Question 2

what happens when we run any query
what is first step

Answer 2

first query gets optimized
then query gets executed

Question 3

when query processing is done, there are how many steps

Answer 3

there are 3 steps to query, internally

Question 4

what are three steps of query processing

Answer 4

Query processing involves 3 basic steps
1. parsing and translation
2. optimization
3. evaluation

Question 5

in first step of query processing, parsing. what does happen here

Answer 5

• query’s syntax is checked, that is known as parsing

Question 6

for parsing internally one thing get created, what do we call it.

Answer 6

for parsing parsing tree is generated

Question 7

after parsing what is next step

Answer 7

translation is next step after parsing

Question 8

what happens in translation

Answer 8

in translation process, query is converted in relational form

Question 9

does query gets translated in Relational Algebra from SQL query

Answer 9

yes

Question 10

what is next step after parsing and translation

Answer 10

optimization of query is next step after parsing and translation

Question 11

what is next step after optimization

Answer 11

evaluation of query is next step after optimization

Question 12

draw flow chart for 3 steps of query processing

Question 13

Example of Query processing

Question 14

definition o ftransaction

Answer 14

action or series of actions, carried out by single user or application program, which reads or updated the contents of the database

Question 15

is transaction logical unit of work

Answer 15

yes, transaction is logical unit of work

Question 16

more points on transaction

Answer 16

it may be an entire or a part of program or a command (SQL for INSERT or UPDATE) and it may involve a large number of operations on a database

Question 17

what happens after transaction is committed

Answer 17

after a transaction is committed, database reaches to a new consistent state

Question 18

can a transaction is roll back or undone after its execution

Answer 18

yes, a transaction may be rolled back or undone after its execution

Question 19

what is compensating transaction

Answer 19

A compensating transaction can reverse the effect of a transaction

Question 20

what is “ state transition of a transaction “

Draw diagram

Question 21

what is meaning of state’s of transaction

Answer 21

when program is in transaction state, from how many steps / processes it goes

this is known as state of transaction

Question 22

Explain Active states of transaction

Answer 22

Database before execution starts

[ read or write operation ]

1. Active state

• pahile DB khali baslela hota, aapan read kiva write operation kel
• mag database active state made aala
• active state made yeun DB read kiva write operation operation perform karel
• manje program kiva transaction, execution state made aala ahe

Active State: It is the initial state of transaction, during execution of statements, a transaction is in Active State

Question 23

Active state madun transaction kuth jate

Answer 23

Active state nantr transaction la don options astat

1. Partially committed
2. Failed

Question 24

Explain failed state of transaction

Answer 24

Partially committed state nantr pan Failed state yeu shekte ani Active state nantr pan failed state yeu shakte

Failed state nanter Aborted state aste, jith DB transaction la kill karto

Question 25

Explain Aborted state of transaction

Answer 25

Aborted state, failed state nantr yete Failed [ kill ] Aborted [ Rollback ] Database before execution starts

Question 26

Jar active state nantr transaction fail nahi zali tr kontya state made jate

Answer 26

Jar transaction fail nahi zali Active State nantr tr, ti partially committed state made jate

Question 27

partially committed state cha kay meaning hoto

Answer 27

transaction la je kam karycha hot te kam transction ne compelte kel, he partially committed state cha meaning hoto R( A ) A = A - 700 W = ( A ) R( B ) B = B + 700 W( B ) -> till here, partially committed Transaction la je kam krycha hot te zal complete, fakt te commit nahi kel azun commit manje kama la save karna

Question 28

what is next step after partially committed state

Answer 28

5:00

Question 29

partially committed main memory [ RAM ] me execute hota he ya primary memory me

Answer 29

5:20

Question 30

After committed state which is the next state

Answer 30

teminated

Question 30

jab committed state perform hogi tab kis memory ka use hoga

Answer 30

5:40

Question 31

what are states of transaction write one be one

Answer 31

active partially committed committed failed aborted

Question 31

committed state ka kya matlab hota he

Answer 31

committed state ka matlab hota he, transaction complete hone ke baad, usse primary memory ya hard disk me update kiya jata he

Question 32

explain each state of transaction in detail

Question 33

when partially committed state takes place

Answer 33

a transaction is partially committed if it has violated serializability or integrity constraint or secondary storage failure for record updation, then the transaction has to be aborted.

Question 34

what if transaction has been successful,

Answer 34

any updates can be safely recorded and the transaction can go to the committed state

Question 35

when does the failed state occurs

Answer 35

it occurs if the transaction can not be committed or the transaction is aborted while in the active state. perhaps due to the user aborting the transaction or as a result of the concurrency control protocol aborting the transaction to ensure the serializability

Question 36

due to user aborting the transaction or as a result of the concurrency control protocol aborting the transaction ensures what

Answer 36

serializability

Question 37

ACID properties of a transaction

Answer 37

Atomicity consistency Isolation Durability

Question 38

Explain Atomicity

Question 39

Explain Consistency

Question 40

Explain Isolation

Question 41

Explain Durability

Question 42

explain architecture of database transaction

Question 43

explain transaction manager

Question 44

what does transaction manger do

Question 45

what is another name of schedular

Question 46

what does recovery manager do

Question 47

what does buffer manager do

Question 49

explain failed state

Answer 49

in any case if transaction cannot be proceeded further then transaction is in failed state

Question 50

rollback kya hota he

Answer 50

rollback ka matlab hota he, transaction apne initial state me aa jata he agar wo fail ho jata h, ya koi error aa jata he

Question 51

definition of committed state

Answer 51

after completion of transaction, it comes in committed state