This article will provide an in-depth look at different databases, including relational, non-relational, analytical, in-memory, and transactional databases. By the end of this article, you’ll have a solid understanding of these databases, which will serve as a base to explore Azure’s data solution offerings.
1. Relational Databases:
A relational database is a type of database that allows administrators to manage data in a structured way by defining the kind of data to be stored. It uses a schema to define tables consisting of rows and columns, and data can be accessed or reassembled in different ways without needing to reorganize the tables. Examples of relational databases in Azure are Azure SQL Database, Azure Database for MySQL, PostgreSQL, and MariaDB.
2. Non-Relational Databases:
Non-relational databases, also known as NoSQL databases, are flexible as they allow admins to store and process data in ways not possible in relational databases. They can handle unstructured data at a large scale. There are several types of NoSQL databases, such as key-value (Azure Cosmos DB, Azure Cache for Redis), document (Azure Cosmos DB), graph (Azure Cosmos DB, Azure Digital Tokens), and columnar (Apache Cassandra, Azure Table Storage).
3. Analytical Databases:
Analytical databases are dedicated to data analysis and can deal with complex query processing requirements. They support tasks related to data warehousing and online analytical processing (OLAP). It’s typically useful for business intelligence (BI) activities like analytical reports, forecasting market trends, etc. Examples in Azure include Azure Synapse Analytics and Azure Analysis Services.
4. In-Memory Databases:
In-memory databases store data in main memory to provide faster response times. By storing data in memory as opposed to disk storage, they eliminate the need for disk IO and thus, offer improved performance. Azure offers Azure Cache for Redis, which is an in-memory database used to increase the performance and scalability of systems that rely heavily on backend data-stores.
5. Transactional Databases:
Transactional databases are used for real-time transactions. They rely on atomicity, consistency, isolation, and durability (ACID) rules to ensure that all transactions are completed successfully and ensure data integrity. If a transaction fails at any point, the system automatically reverts to its previous state. An example on Azure is Azure SQL Database.
Here’s a quick comparison table to sum up:
| Database Type | Azure Services | Key Characteristics |
|---|---|---|
| Relational | Azure SQL, MySQL, MariaDB | Structured, Schema Based |
| Non-Relational | Azure Cosmos DB, Redis | Flexible, Scalable |
| Analytical | Azure Synapse, Analysis Service | Complex data analysis |
| In-Memory | Azure Cache for Redis | Fast response, Reduced disk IO |
| Transactional | Azure SQL | ACID principles, Real-time transactions |
Understanding the key characteristics of each type of database will help you choose the one that best fits your data needs. Remember that in Azure, most of these database types are available as managed services, which means that Azure takes care of the maintenance, backup, scaling, and patching, allowing you to focus more on application development.
Remember, these types of databases are not mutually exclusive, and in practice, you might need to use more than one type depending on the specifics of your project.
To prepare for the DP-900 exam, make sure to practice these concepts in the Azure portal. Understanding these types of databases is fundamental for managing and operating with data on Azure. I hope this article provides some clarity and understanding about the types of databases required for the DP-900 Azure exam. Happy Studying!
Practice Test
Single Select: What type of database is used for online transaction processing?
- a. OLTP
- b. OLAP
- c. Data Warehouse
- d. NoSQL
Answer: a. OLTP
Explanation: OLTP (Online Transaction Processing) is a category of systems that manage transaction-oriented applications on the internet.
True/False: A NoSQL database provides less flexibility in accommodating and managing various data models.
Answer: False
Explanation: NoSQL databases are designed to expand the variety of data models, including key-value, document, columnar, and graph formats.
Single Select: Which database types does Microsoft Azure support?
- a. Relational
- b. NoSQL
- c. Both a and b
- d. None of the above
Answer: c. Both a and b
Explanation: Microsoft Azure supports a variety of databases including both relational and NoSQL.
Multiple Select: Which of the following are types of NoSQL databases?
- a. MongoDB
- b. Cassandra
- c. Oracle
- d. DynamoDB
Answer: a. MongoDB, b. Cassandra, d. DynamoDB
Explanation: MongoDB, Cassandra, and DynamoDB are types of NoSQL databases while Oracle is an SQL database.
True/False: Data collected in Operational databases can be used directly for decision-making tasks.
Answer: False
Explanation: Data in operational databases is primarily used for data transactions, not for decision-making tasks.
Single Select: Document databases, key-value databases, and graph databases all fall under which category?
- a. SQL
- b. NoSQL
- c. OLAP
- d. OLTP
Answer: b. NoSQL
Explanation: NoSQL databases can accommodate a wide array of data models, including key-value, document, columnar, and graph formats.
Multiple Select: Choose the names of types of relational databases.
- a. MySQL
- b. PostgreSQL
- c. Microsoft Access
- d. MongoDB
Answer: a. MySQL, b. PostgreSQL, c. Microsoft Access
Explanation: MySQL, PostgreSQL, and Microsoft Access are examples of Relational Database Systems. MongoDB is a NoSQL database.
True/False: Azure Synapse Analytics is a fully integrated, end-to-end data analytics solution.
Answer: True
Explanation: Azure Synapse blends big data and data warehousing into an analytics service, providing a fast, easy, and collaborative approach.
Single Select: Which type of database is primarily used for data analysis and reporting?
- a. OLAP
- b. OLTP
- c. NoSQL
- d. All of the above
Answer: a. OLAP
Explanation: OLAP (Online Analytical Processing) is a type of database used for data analysis and reporting.
True/False: Graph databases are best for dealing with highly interconnected datasets.
Answer: True
Explanation: Graph databases are designed to handle data that is interconnected in nature and can handle complex queries with multiple joins effectively.
Single Select: Which type of database is best suited for hierarchical data storage?
- a. Relational database
- b. NoSQL database
- c. Graph database
- d. None of the above
Answer: c. Graph database
Explanation: The graph database is most suited for use where data is highly interconnected and relationships among data are equally important, like hierarchical data.
Multiple Select: What are the capabilities of Azure Cosmos DB?
- a. It supports NoSQL
- b. It is a globally distributed service
- c. It can scale throughput
- d. It does not support multi-models
Answer: a. It supports NoSQL, b. It is a globally distributed service, c. It can scale throughput
Explanation: Azure Cosmos DB is a fully-managed NoSQL database service. It supports multi-models and can scale throughput and storage globally.
True/False: In a NoSQL database, the schema needs to be defined before you can store data.
Answer: False
Explanation: Unlike relational databases, most NoSQL databases are schema-less. This means the structure does not need to be defined in advance.
Single Select: Which type of database is designed for big data solutions?
- a. Columnar Database
- b. Graph Database
- c. Document Database
- d. All of the above
Answer: a. Columnar Database
Explanation: Columnar databases store data by columns rather than rows, leading to better performance for big data solutions like data warehouses.
True/False: A cloud database is a database that runs on a cloud computing platform and provides access to data from anywhere in the world.
Answer: True
Explanation: A cloud database is designed to deliver a range of functions across the internet, through a browser or a dedicated app, making the data accessible from anywhere.
Interview Questions
What is a relational database?
A relational database is a type of database that uses a structured query language (SQL) for defining and manipulating the data, which is stored in tables.
Describe a Non-relational database in the context of Microsoft Azure.
Non-relational databases in Azure, also known as NoSQL databases, are flexible and schema-less databases that are optimized for operations that require large amounts of data. Azure Cosmos DB is a globally distributed, multi-model database service for managing data at scale.
What advantage does a relational database have over non-relational databases?
Relational databases are typically more effective when handling structured data and complex queries, as the data is organized into columns and rows, providing an efficient way to manage and retrieve data.
What is a column-store index in Azure SQL Database?
Column-store index organizes the data in columns instead of rows which is much efficient for data warehousing and analytics workloads, which typically involve summarizing, aggregating, or browsing large sets of data.
What is an in-memory database?
An in-memory database (IMDB) is a type of database that primarily relies on main memory for computer data storage. Azure offers Azure Cache for Redis, a fully managed in-memory cache to power fast, scalable applications.
What is a Data Warehouse?
A Data Warehouse is a large store of data collected from a wide range of sources within a company and used to guide management decisions. Azure Synapse Analytics is an example of Data Warehouse service in Azure.
What is a graph database and how is it used in Azure?
A graph database is a type of NoSQL database that uses graph theory to store, map and query relationships. It’s used in Azure Cosmos DB’s Gremlin API, to model many-to-many relationships.
What are time-series databases and provide an example from Azure?
Time-series databases are optimized for handling time-series data, i.e., data that’s time-stamped. An example from Azure is Azure Time Series Insights, which is a fully managed analytics, storage, and visualization service for managing IoT-scale time-series data.
What is Azure Table Storage?
Azure Table storage is a service that stores structured NoSQL data in the cloud, providing a key/attribute store with a schema-less design.
In the context of Microsoft Azure, explain what is Azure SQL Database?
Azure SQL Database is a general-purpose relational database, provided as a managed service. With it, you can create a highly available and high-performance data storage layer for the applications and solutions in Azure.
What is a spatial database and provide an example from Azure?
A spatial database stores data related to objects in space, including points, lines and polygons. Azure Cosmos DB is an example of a spatial database within Azure, as it includes spatial functions.
How does Microsoft Azure define Data Lake?
Azure Data Lake is a highly scalable public cloud service that allows developers, scientists, business professionals, and other Microsoft customers to gain insight from large, complex data sets.
What is Azure Database for PostgreSQL?
Azure Database for PostgreSQL is a relational database service in the Microsoft cloud based on the open-source Postgres database engine. It’s a fully managed service providing power, flexibility, and scalability.
What could be the typical use-case for Azure Cosmos DB?
Azure Cosmos DB is ideal for globally distributed applications that require extremely low latency, elastic scalability and high availability.
Can you define Azure Stream Analytics?
Azure Stream Analytics is a real-time analytics and complex event-processing engine that is designed to analyze and visualize streaming data in real-time.
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