This document discusses transaction system concepts including: - A transaction is a collection of operations that form a single logical unit of work accessing and modifying data items. - Transactions have four main properties: atomicity, consistency, isolation, and durability (ACID). - A transaction system state includes active, partially committed, aborted, committed, and failed states. - Recovery from transaction failures involves techniques like log-based recovery and checkpointing to restore data after failures like power outages or disk crashes.

1. Class : MCA 2nd (2014 - 2015)
Topics : Transection System Concepts
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By : Mr Jitendra Thakur

2. TRANSECTION
SYSTEM CONCEPTS

3. » Introduction :
» Operation of Transaction :
» Properties of Transaction :
» Transaction System State :
» Explanation :
» Transaction Process System :
» Recovery from Transaction Failure :
» Types of Failure :
» Recovery Method :
» Example :
» Recoverably Schedule :
» Example :
» Thank you :

4. » Collection of operation that from a single
logical unit of work is called transection
» A transection is a unit of program
execution that access and possibly obtain
various data item

5. » Main operation of transection :
I. Read (X) ; -which transfer the data item X
from the data base to a logical buffer
belonging to a transection that execute the
read operation
II. Write (x); -which transfer the data item from
the logical buffer of the transection that
executed if write back to the data base

6. » Transection have 4 properties : likely
» ACID TEST
I. Atomicity
II. Consistency
III. Isolation
IV.Durability –after commit it will be stable

7. Partially
committ
ed
Failed
Commi
tted
Aborted
Active

8. » Active – it’s the initial state ,the transection stay
in this state while its executed .
» Partially(not permanent save ) committed – after
the final statement has been executed .
» Aborted – after the transection has been role
back and the data base has been restored .
» Committed – a transection that complete its
execution successfully is said to be committed .
» Failed – after the discovery that normal
execution can be longer processed .

9. TPS are the system which include large size data base and
allow many users to use same data base concurrently
Example 1-railway reservation system
2-credit card system
Other similar system is called TPS .

10. » Computer like any other device to subject to
failure include power failure disk crash software
error etc
» In this case the database patterning the database
is lost

11. » Lose of volatize storage –log based recovery ,
buffered management , check points and
pshadaw paging techniques.
» Non volatize storage lose – hard disk ,magnetic
disk and tape ,if a failure occur the data is used
in restoring concept in the data base

12. » Cascading recovery (roll back )- a single
transaction failure follow a series of transaction
roll back is called cascading roll back .
» If T1 is failure then the all series of transaction
will be failed because hare in this ex T3 is
depend on T2 and T2 depend on T1.

13. » T1 T2 T3
» Read (x);
» Read(y);
» Z=x+y;
» Write(z);
--------------------------------------------------------------
» Read (z);
» Write(z);
---------------------------------
Read(z)
Depend Depend

14. » In this schedule T3 transaction perform only one
transaction read(z)
» T3 is not dependent to transaction T1 and T2
» All transaction work as a separately .
» Not depend with each others.
» Consider following example .

15. » T1 T2 T3
Independent Independent
» Read(x);
» Write(x);
» ----------------------------------------------------------------
» Read(x);
------------------------------------------
Read(x);
(committed)