Podcast
Questions and Answers
What type of No-SQL database is optimized to retrieve columns of data?
What type of No-SQL database is optimized to retrieve columns of data?
Which No-SQL database type has the highest flexibility and complexity?
Which No-SQL database type has the highest flexibility and complexity?
In the context of caching, what is its primary function?
In the context of caching, what is its primary function?
For which use case would a Document Store be the most appropriate choice?
For which use case would a Document Store be the most appropriate choice?
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Which No-SQL database type is most suitable for managing session data or shopping cart details?
Which No-SQL database type is most suitable for managing session data or shopping cart details?
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Which of the following describes a characteristic of relational databases?
Which of the following describes a characteristic of relational databases?
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What is a primary focus of Online Transaction Processing (OLTP) systems?
What is a primary focus of Online Transaction Processing (OLTP) systems?
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What is an example of a non-relational database?
What is an example of a non-relational database?
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In what context are data warehouses typically used?
In what context are data warehouses typically used?
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Which of the following best describes the structure of data in OLAP systems?
Which of the following best describes the structure of data in OLAP systems?
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Which of the following is incorrect regarding ACID properties?
Which of the following is incorrect regarding ACID properties?
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What type of queries are typically processed in OLTP systems?
What type of queries are typically processed in OLTP systems?
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Which of the following databases is known for its use in big-data analytics?
Which of the following databases is known for its use in big-data analytics?
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What is a defining feature of Redis compared to Memcached?
What is a defining feature of Redis compared to Memcached?
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Which functionality is a characteristic of Memcached?
Which functionality is a characteristic of Memcached?
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What does ETL stand for in the context of data warehousing?
What does ETL stand for in the context of data warehousing?
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Which statement best describes the purpose of a data warehouse?
Which statement best describes the purpose of a data warehouse?
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Which of the following is a limitation of Memcached?
Which of the following is a limitation of Memcached?
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In the ELT approach for data warehousing, what is the correct order of processes?
In the ELT approach for data warehousing, what is the correct order of processes?
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Which caching system offers support for backup and restore operations?
Which caching system offers support for backup and restore operations?
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What type of data is typically found in a data warehouse?
What type of data is typically found in a data warehouse?
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Study Notes
Database Models
- Relational/SQL databases are highly structured, with data organized into tables, enforcing integrity and reducing anomalies.
- Non-relational/No-SQL databases offer flexible data models, supporting rapid changes and handling large, complex queries. Examples include MongoDB, Cassandra, CosmosDB, Redis, CouchDB, and Aurora.
- Relational Databases use SQL (Structured Query Language) to access data. Examples include MS SQL, MySQL, Oracle, and PostgreSQL.
Database Workloads
- OLTP (Online Transaction Processing) focuses on operational data, processing transactions with small, simple queries, aiming for millisecond responses.
- OLAP (Online Analytical Processing) focuses on historical data for analysis and reporting, using large, complex queries with response times ranging from seconds to hours.
Relational vs. Non-relational Databases
- Relational/OLTP: Examples include Oracle, PostgreSQL, MS SQL, and MySQL.
- Relational/OLAP: Examples include Oracle, PostgreSQL, MS SQL, and MySQL.
- Non-relational/OLAP: Examples include Hadoop and HDInsight for big-data analytics.
- Non-relational/OLTP: Examples include key-value stores, columnar databases, and document stores like MongoDB, Cassandra, and Riak.
NoSQL Database Types
- Key-Value Stores: Store data as key-value pairs, ideal for session data or shopping cart data.
- Document Stores: Store data in documents (XML, JSON, etc.), offering flexible schema-less designs and supporting complex documents with key-value pairs. Examples include e-commerce or analytics platforms.
- Columnar Databases: Optimized for retrieving columns of data, often used for content management systems (CMS) or blogging platforms.
- Graph Databases: Represent data as a network of interconnected nodes and relationships, ideal for data with strong connections and complex relationships.
NoSQL Database Comparison
- Key-Value Stores offer high flexibility, minimal complexity, high performance, and high scalability.
- Column Stores provide moderate flexibility, low complexity, high performance, and high scalability.
- Document Stores offer high flexibility, low complexity, high performance, and variable scalability (typically high).
- Graph Databases provide high flexibility, high complexity, variable performance, and variable scalability.
CAP Theorem
- The CAP theorem states that a distributed database system can only satisfy two of three properties: Consistency, Availability, and Partition Tolerance.
- Consistency ensures data is consistent across all nodes.
- Availability ensures the system remains available even if some nodes are down.
- Partition Tolerance ensures the system remains operational even with network partitions.
Database Caching
- Caching stores frequently accessed data in temporary memory to improve performance and reduce database workloads.
- Redis and Memcached are popular caching systems, both offering sub-millisecond response times.
- Redis supports various data structures (strings, lists, sets) and persists cache data even after reboots.
- Memcached supports strings and objects but does not persist data after reboots.
Redis vs. Memcached
- Redis is an open-source, in-memory, key-value data store offering sub-millisecond response times and supporting various data structures. It persists data across reboots.
- Memcached is an open-source, in-memory, object store offering sub-millisecond response times and supporting strings and objects. It does not persist data across reboots.
Data Warehousing
- Data Warehouses are repositories for structured, filtered data designed to facilitate business intelligence (BI) activities and support analytics.
- ETL (Extract, Transform, Load): A common approach to populate data warehouses, involving extracting data from multiple sources, transforming it into a consistent format, and loading it into the warehouse.
- ELT (Extract, Load, Transform): Another approach where data is first extracted and loaded into the warehouse, and transformation occurs later.
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