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Database Articles
Page 147 of 547
Difference between Centralized Data Storage and Distributed Data Storage
The capacity to retain data is rapidly emerging as one of the most crucial features of contemporary business, government, and even personal life. Most successful companies have data storage systems that are properly organized, secure, and easy to access when necessary. Accounting records, policy documents, and human resources information, to mention a few examples, must be kept in a safe system that provides security against data loss and theft and has a reliable recovery method in place. Saving space and money through effective data storage is preferable to maintaining data in files or on a computer. Centralized data storage ...
Read MoreDifference between Bit Rate and Baud Rate
In telecommunication and electronics engineering, Bit Rate and Baud Rate are two commonly used terms in the context of data communication. Both these terms represent the speed of data transmission in the computer networks. The basic difference between Bit Rate and Baud Rate is that the Bit Rate is defined as the number of bits (binary 0s and 1s) transmitted over a network in unit time, whereas Baud Rate is defined as the number of signal units transmitted over a network in unit time. Thus, bit rate and baud rate both the related terms, and the relationship between these ...
Read MoreHow to customize the Result of JPA Queries with Aggregation Functions?
Most of the time when we use JPA queries, the result obtained is mapped to an object/particular data type. But When we use aggregate function in queries, handling the result sometimes require us to customize our JPA query. Let’s understand this with help of an example (Department, Employee) − Dept.java @Entity public class Dept { @Id private Long id; private String name; @OneToMany(mappedBy = "dep") private List emp; //Getters //Setters } A department can have one or more ...
Read MoreHow to connect hibernate with MySQL Database?
In this article, we will see how we can connect to MySQL database using an ORM (object relational mapping) framework like hibernate. First of all, we need to add maven dependency for hibernate in our pom.xml file − org.hibernate hibernate-core 5.6.2.Final Now, let us define an entity class that will be mapped to a database table using hibernate. @Entity @Table( name = " Employee") public class Employee { @Id @GeneratedValue(strategy = GenerationType.AUTO) Long id; @Column(name = ...
Read MoreHow does Hibernate Second Level Cache Works?
Caching helps to reduce database network call, for executing queries. First level cache is linked with a session. It is implemented implicitly. First level cache exist only till the session object is there. Once session object is terminated/closed, there will be no cache objects. Second level cache works across multiple sessions objects. It is linked with a session factory. Second level cache objects are available to all the session in a single session factory. These cache objects are terminated when that particular session factory is closed. Implementing second level caching We need to add the following dependencies in order to ...
Read MoreWhat is Bucketing in Hive?
Bucketing is a method in Hive which is used for organizing the data. It is a concept of separating data into ranges known as buckets. Bucketing in hives comes helpful when the use of partitioning becomes hard. A user can determine the range of a specific bucket by the hash value. Partitioned tables can be bucketed to separate the data further to perform queries more efficiently. Every bucket is stored as a file within the table or the partition’s directories on HDFS. The records having a similar value within a column are always stored in the same bucket. Bucketing can ...
Read MoreRDD Shared Variables In Spark
The full name of the RDD is a distributed database. Spark performance is based on this ambiguous set, enabling it to consistently cope with major data processing conditions, including MapReduce, streaming, SQL, machine learning, graphs, etc. Spark supports many programming languages, including Scala, Python, and R. RDD also supports the maintenance of material in these languages. How to create RDD Spark supports RDDS architecture in many areas, including local file systems, HDFS file systems, memory, and HBase. For the local file system, we can create RDD through the following way − val distFile = sc.textFile("file:///user/root/rddData.txt") By default, Spark takes ...
Read MoreSqoop Integration with Hadoop Ecosystem
Data was previously stored in relational data management systems when Hadoop and big data concepts were not available. After introducing Big Data concepts, it was essential to store the data more concisely and efficiently. However all data stored in the related data management system needs to be transferred to the Hadoop archive. With Sqoop, we can transfer this amount of personal data. Sqoop transfers data from a related database management system to a Hadoop server. Thus, it facilitates the transfer of large volumes of data from one source to another. Here are the basic features of Sqoop − Sqoop ...
Read MoreDifference between Sync and Backup
The act of copying data from one area to another, typically from one hard drive to another, is what we normally call as "backing up." This can be done manually or automatically. Synchronization is the process of ensuring that two different sites have the same collection of files by manually or automatically copying or deleting them as required. Syncing is a faster option, but it comes with a risk. Read through this article to find out more about Sync and Backup and how they are different from each other. What is Sync? Synchronization (sync) is the process of ensuring that ...
Read MoreDifference between Delete and truncate in sql query
Both the TRUNCATE statement and the DELETE statement are included in the category of SQL queries for deleting the data stored in a table. They carry out deletion operations on records or rows of a table that are no longer needed. A condition is applied before each entry in the table that is being deleted when using the DELETE command. To put it another way, it is possible to delete one or more rows all at once. However, with the TRUNCATE command, each row is removed from the table simultaneously. When we delete something using the DELETE query, a log ...
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