Skip to main content

Schedule in DBMS

Schedule

A series of operation from one transaction to another transaction is known as schedule. It is used to preserve the order of the operation in each of the individual transaction.

Schedule in DBMS


1. Serial Schedule
The serial schedule is a type of schedule where one transaction is executed completely before starting another transaction. In the serial schedule, when the first transaction completes its cycle, then the next transaction is executed.

For example: Suppose there are two transactions T1 and T2 which have some operations. If it has no interleaving of operations, then there are the following two possible outcomes:
  1. Execute all the operations of T1 which was followed by all the operations of T2. 
  2. Execute all the operations of T1 which was followed by all the operations of T2. 

  • In the given (a) figure, Schedule A shows the serial schedule where T1 followed by T2.
  • In the given (b) figure, Schedule B shows the serial schedule where T2 followed by T1.

2. Non-serial Schedule
  • If interleaving of operations is allowed, then there will be non-serial schedule.
  • It contains many possible orders in which the system can execute the individual operations of the transactions.
  • In the given figure (c) and (d), Schedule C and Schedule D are the non-serial schedules. It has interleaving of operations.

3. Serializable Schedule
  • The serializability of schedules is used to find non-serial schedules that allow the transaction to execute concurrently without interfering with one another. 
  • It identifies which schedules are correct when executions of the transaction have interleaving of their operations.
  • A non-serial schedule will be serializable if its result is equal to the result of its transactions executed serially.

Schedule in DBMS

Schedule in DBMS

Schedule in DBMS

Schedule in DBMS



Here,

Schedule A and Schedule B are serial schedule.

Schedule C and Schedule D are Non-serial schedule.
Labels:

Comments

Post a Comment

Please do not enter any spam link in the comment box.

Popular posts from this blog

DBMS Keys

DBMS Keys KEYS in DBMS is an attribute or set of attributes which helps you to identify a row (tuple) uniquely in a relation(table). They allow you to find the relation between two tables. Keys help you uniquely identify a row in a table by a combination of one or more columns in that table. Key is also helpful for finding unique record or row from the table. Database key is also helpful for finding unique record or row from the table. Example: Employee ID FirstName LastName 11 Andrew Johnson 22 Tom Wood 33 Alex Hale In the above-given example, employee ID is a primary key because it uniquely identifies an employee record. In this table, no other employee can have the same employee ID. Here are some reasons for using sql key in the DBMS system. Keys help you to identify any row of data in a table. In a real-world application, a table could contain thousands of records. Moreover, the records could be duplicated. Keys in RDBMS ensure that you can uniquely identify a table record despite ...
Post a Comment
Read more

Implement Echo client and Echo server using TCP Sockets

Implement Echo client and Echo server using TCP Sockets EchoServer.java import java.net.*; import java.io.*; public class EServer { public static void main(String args[]) { ServerSocket s=null; String line; DataInputStream is; PrintStream ps; Socket c=null; try { s=new ServerSocket(9000); } catch(IOException e) {} try { System.out.println(e); c=s.accept(); is=new DataInputStream(c.getInputStream()); ps=new PrintStream(c.getOutputStream()); while(true) { line=is.readLine(); ps.println(line); }} catch(IOException e) { System.out.println(e); }}} EchoClient.java import java.net.*; import java.io.*; public class EClient { public static void main(String arg[]) { Socket c=null; String line; DataInputStream is,is1; PrintStream os; try { InetAddress ia = InetAddress.getLocalHost(); c=new Socket(ia,9000); } catch(IOException e) {} try { System.out.println(e); os=new PrintStream(c.getOutputStream()); is=new DataInputStream(System.in); is1=new DataInputStream(c.getInputStream()); while(true) { Sys...
Post a Comment
Read more

four methods overload these methods

Write a program in java which has the following classes and methods:  Class : OverloadDemo Methods : test() Declare four methods with the same name “test()” and overload these methods class OverloadDemo{  public void test(){  System.out.println("It's a test method for null.");  }  public void test(int n){  System.out.println("It's a test method for displaying the int value "+n);  }  public void test(double d){  System.out.println("It's a test method for displaying the double value "+d);  }  public void test(String s){  System.out.println("It's a test method for displaying the String "+s);  }  }  class overClass{  public static void main(String[] args) {  OverloadDemo old = new OverloadDemo();  old.test();  old.test(12);  old.test(25.35);  old.test("Subham");  }  } OUTPUT: It's a test method for null. It's a test method for displaying the int value 12 It's a test method for ...
Post a Comment
Read more