Difference between serial and non-serial schedule?

Answer 1

Serial Schedule

Non-Serial Schedule

A serial schedule is a sequence of operation by a set of concurrent transaction that preserves the order of operations in each of the individual transactions.

A non-serial schedule is a schedule where the operations of a group of concurrent transactions are interleaved.

Transactions are performed in serial order.

Transactions are performed in non-serial order, but result should be same as serial.

No interference between transactions

Concurrency problem can arise here.

It does not matter which transaction is executed first, as long as every transaction is executed in its entirely from the beginning to end.

The problem we have seen earlier lost update, uncommitted data, inconsistent analysis is arise if scheduling is not proper.

A serial schedule gives the benefits of concurrent execution without any problem

In this schedule there is no any benefit of concurrent execution.

Serial schedule that does interleaved the actions of different transactions.

Where non-serial schedule has no only fix actions of any transaction.

EXAMPLE:

If some transaction T is long, the other transaction must wait for T to complete all its operations.

EXAMPLE:

In this schedule the execution of other transaction goes on without waiting the completion of T.

If we consider transaction to be independent serial schedule is correct based on (property ACID) above assumption is valid.

The objective behind serializability is to find the non-serial schedule that allows transactions to execute concurrently without interfering one another.