Found 1719 Articles for Big Data Analytics

A distributed database is the one where all the storage devices are not attached to a common CPU (central processing unit). It may be distributed over a network of interconnected computers, or it may be stored in multiple computers located in the same physical location.Distributed Database Management SystemA distributed database management system (DDBMS) manages the database as in if it is stored in the same computer.The DDBMS synchronizes all the data in a periodical manner and in situations when multiple users are accessing the same data and ensures that updation and deletion performed on the data at one location shall ... Read More

A Clustered index is one of the special types of index which reorders the way records in the table are physically stored on the disk. It sorts and stores the data rows in the table or view based on their key values. It is essentially a sorted copy of the data in the indexed columns.Sometimes we are asked to create an index on a non-unique key like dept-id in the below table. There could be several employees in each department. Here, all employees belonging to the same dept-id are considered to be within a single cluster, and the index pointers ... Read More

In the primary index there is a one-to-one relationship between the entries in the index table and records in the main table. Primary index is used on a primary key.Types of Primary IndexPrimary index are of two types, which are as follows −Dense Primary IndexIn a dense primary index an index record appears for every search key value in the main table that means each and every record in the main table has an entry in the index.ExampleGiven below is an example of dense primary index −A pointer stores the address of a record.Non-Dense / Sparse Primary indexAn index record ... Read More

A Database Management System (DBMS) is a mix of computer software, hardware, and data intended to electronically control information by means of computer preparation.Two sorts of database management systems are DBMS and FMS.In straightforward terms, a File Management System (FMS) is a Database Management System that enables access to single records or tables at once.FMS oblige level records that have no connection to different documents.The FMS was the ancestor for the Database Management System (DBMS), which enables access to various records or tables at once.We have to utilize circle stockpiling for the database, and to exchange pieces of information between ... Read More

File organization is the way of storing data in the file. It is very useful as it determines ways of accessing it, storing it while maintaining the flexibility of the system.Role of file organizationHence, the roles of file organization are as follows −It provides flexibility.Easy access of data in files.Easy storage.Decrease the complexity of the overall system and files are stored and well maintained.Provide security to data.Saves users time in searching for particular information / data in file as every data is arranged so nicely.MethodsThe methods of file organization are as follows −ContiguousData and files are arranged in contiguous address ... Read More

Let us begin by understanding the hashed file organisation.Hashed File OrganisationHashed file organisation is also called a direct file organisation.In this method, for storing the records a hash function is calculated, which provides the address of the block to store the record. Any type of mathematical function can be used as a hash function. It can be simple or complex.Hash function is applied to columns or attributes to get the block address. The records are stored randomly. So, it is also known as Direct or Random file organization.If the generated hash function is on the column which is considered as ... Read More

Indexing is one of the techniques used to optimize performance of a database by reducing the number of disk accesses that are required when a query is processed.A database index is a data structure that is helpful to quickly locate and access the data in a database table.Indexes are created using database columns.The first column is the Search key which contains a copy of the primary key or candidate key of the table.The second column is the data reference that contains a set of pointers which hold the address of the disk block where the key value can be found.Structure ... Read More

Database failure is a quite common problem of information technology. It can occur even with good database system software. There may be a simple error which can lead to loss of the complete database.Causes of database failureSome of the causes for database failure are as follows −Database file corruptionIf a file in the database is corrupted or damaged, it can lead to the database failure. The file can become corrupt due to the following reasons −Changes in the SQL Server account.Accidental data deletion.File header corruption.Errors in accessing the data.InterruptionWhen the server or computer is not shut down properly or during ... Read More

If any transaction that performs a dirty read operation from an uncommitted transaction and also its committed operation becomes delayed till the uncommitted transaction is either committed or rollback such type of schedules is called as Recoverable Schedules.Types of recoverable schedulesThere are three types of recoverable schedules which are explained below with relevant examples −Cascading schedulesCascadeless SchedulesStrict Schedules.The types of recoverable schedules are given below in form of a chart −Recoverable scheduleFirst, let us see an example of a recoverable schedule.T1T2R(X)W(X)W(X)R(X)commitCommitHere, transaction T2 is reading value written by transaction T1 and the commit of T2 occurs after the commit of ... Read More

OLAP represents online insightful handling and can be characterized as: "Online logical preparation alludes to an assortment of exercises typically performed by End-clients in the online framework."Online transaction processing, also known as OLTP, supports transaction-oriented applications in a 3-tier architecture. OLTP administers day to day transactions of an organization.DifferencesThe major differences between OLAP and OLTP are as follows −OLAPOLTPOLAP is abridged for Online Analytical handling.OLTP is truncated for online exchange handling.OLAP application upholds Management-basic errands.OLTP application underpins strategic undertakings.The reason for OLAP is to assist with arranging, critical thinking, and choice help.The information base plan is de-standardized.Few tables are available ... Read More