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 are states of transaction
write one be one

Answer 21

active
partially committed
committed
failed
aborted

Question 22

explain each state of transaction in detail

Question 23

when partially committed state takes place

Answer 23

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 24

what if transaction has been successful,

Answer 24

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

Question 25

when does the failed state occurs

Answer 25

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 26

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

Answer 26

serializability

Question 27

ACID properties of a transaction

Answer 27

Atomicity
consistency
Isolation
Durability

Question 28

Explain Atomicity

Question 29

Explain Consistency

Question 30

Explain Isolation

Question 31

Explain Durability

Question 32

explain architecture of database transaction

Question 33

explain transaction manager

Question 34

what does transaction manger do

Question 35

what is another name of schedular

Question 36

what does recovery manager do

Question 37

what does buffer manager do