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DBMS Articles
Page 5 of 27
Evolution of Distributed Computing Systems
Introduction Distributed computing systems refer to a network of interconnected devices that share resources and work together to achieve a common goal. evolution of distributed computing systems has been rapid, and it has transformed way we use technology in our daily lives. From simple file sharing systems to advanced cloud computing, distributed computing systems have come a long way. In this article, we will discuss evolution of distributed computing systems and explore some of examples. Early Days of Distributed Computing The early days of distributed computing can be traced back to 1960s, where researchers began experimenting with idea of sharing ...
Read MoreEvent Ordering in Distributed System
Introduction Distributed systems have become an integral part of our modern-day technological infrastructure. They have made it possible to deliver services at scale, provide better resilience, and enable better fault tolerance. However, designing distributed systems is a challenging task, and one of most significant challenges is maintaining ordering of events in system. This article will discuss event ordering in distributed systems and provide examples of different techniques used to achieve it. Event Ordering Event ordering is essential in distributed systems because it determines order in which events occur. In a distributed system, events can happen concurrently on different nodes, and ...
Read MoreDifference between Static and Dynamic Hashing
Hashing is a computation technique in which hashing functions take variable-length data as input and issue a shortened fixed-length data as output. The output data is often called a "Hash Code", "Key", or simply "Hash". The data on which hashing works is called a "Data Bucket". Characteristics of Hashing Technique Hashing techniques come with the following characteristics − The first characteristic is, hashing technique is deterministic. Means, whatever number of times you invoke the function on the same test variable, it delivers the same fixed-length result. The second characteristic is its unidirectional action. There is no way you can ...
Read MoreWhat are different types of DBMS languages?
Once data is stored or filled it requires manipulation like insertion, deletion, updating, and modification of data. For these operations a set of languages are provided by the database management system (DBMS). So, the database languages are used to read, update and store data in the database.The different types of DBMS languages are as follows −Data Definition Language (DDL) − Create, Drop, Truncate, Rename.Data Manipulation language (DML) − Select, Insert, Delete, Update.Data Control Language (DCL) − Revoke, Grant.Transaction Control Language (TCL) − Rollback, Commit.The DBMS languages are pictorially represented as follows −Data Definition Language (DDL)It is a language that allows ...
Read MoreExplain about nested queries in DBMS
A nested query is a query that has another query embedded within it. The embedded query is called a subquery.A subquery typically appears within the WHERE clause of a query. It can sometimes appear in the FROM clause or HAVING clause.ExampleLet’s learn about nested queries with the help of an example.Find the names of employee who have regno=103The query is as follows −select E.ename from employee E where E.eid IN (select S.eid from salary S where S.regno=103);Student tableThe student table is created as follows −create table student(id number(10), name varchar2(20), classID number(10), marks varchar2(20)); Insert into student values(1, 'pinky', 3, ...
Read MoreWhat is tier-3 architecture in DBMS?
The overall design of the Database Management System (DBMS) depends on its architecture. A large amount of data on web servers, Personal Computers (PC) and other elements are linked with networks with the help of basic client or server architecture.PCs and workstations are part of Client architecture that are connected over the network. The architecture of DBMS depends on how the users are linked to the database.There are three kinds of DBMS Architecture, which are as follows −Tier-1 Architecture.Tier-2 Architecture.Tier-3 Architecture.Tier-3 ArchitectureThe 3-tier architecture contains one more layer between the client and the server.In this architecture, there is no direct ...
Read MoreDifference between DDL and DML in DBMS
Anybody dealing with databases must comprehend the distinction between DDL and DML commands because it has an impact on how data is saved, accessed, and modified. A collection of commands called DDL are used to specify a database's structure. Database objects including tables, views, indexes, and constraints can be created, modified, and deleted using these commands. DDL statements specify how the data is arranged and accessed rather than altering the data that is stored in the database. DML, on the other hand, is a set of instructions used to work with the data that is kept in the ...
Read MoreWhat are the applications of DBMS?
The Database Management System (DBMS) is defined as a software system that allows the user to define, create and maintain the database and provide control access to the data.It is a collection of programs used for managing data and simultaneously it supports different types of users to create, manage, retrieve, update and store information.Applications of DBMSIn so many fields, we will use a database management system.Let’s see some of the applications where database management system uses −Railway Reservation System − The railway reservation system database plays a very important role by keeping record of ticket booking, train’s departure time and ...
Read MoreWhat are the DCL commands in DBMS?
Data control language (DCL) is used to access the stored data. It is mainly used for revoke and to grant the user the required access to a database. In the database, this language does not have the feature of rollback.It is a part of the structured query language (SQL).It helps in controlling access to information stored in a database. It complements the data manipulation language (DML) and the data definition language (DDL).It is the simplest among three commands.It provides the administrators, to remove and set database permissions to desired users as needed.These commands are employed to grant, remove and deny ...
Read MoreThe concept of indexing in Apache Cassandra
Indexing in Apache Cassandra is a way to improve the efficiency and performance of queries on non-primary key columns. In Cassandra, data is organized in tables and each table has a primary key, which consists of one or more columns that uniquely identify each row in the table. Queries that use the primary key to retrieve data are very efficient, but queries that use other columns in the WHERE clause can be slower. Cassandra has secondary indexes that enable querying on columns other than the main key columns to solve this problem. A secondary index is built on a table's ...
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