Explore key principles of CouchDB architecture and its foundational concepts through this quiz designed to reinforce your understanding of document-oriented databases, replication, and data consistency. Test your foundational knowledge of distributed database systems and their practical applications.
Which of the following best describes how CouchDB stores data within its database system?
Explanation: CouchDB stores data in the form of JSON documents, which allows for flexible and schema-less storage. Tables and structured columns are typical of relational databases, not document databases. Storing text files as CSV or using unstructured binary blobs would not exploit the document-oriented nature of CouchDB.
What protocol does CouchDB primarily use to interact with database clients and perform operations, such as reading or writing data?
Explanation: CouchDB implements a RESTful HTTP API, making it accessible with standard web protocols and simple tools like browsers or HTTP clients. FTP is used for file transfers, SMTP is for email, and RPC is for remote procedure calls, which are not CouchDB's interface methods.
In CouchDB, which feature allows users to build custom queryable indexes by defining map and reduce functions?
Explanation: MapReduce Views in CouchDB are used to create custom indexes and aggregate data using user-defined functions. Triggers and foreign keys are features found in some relational databases, not in document-oriented databases. Schedulers are used for managing tasks rather than querying data.
Which ACID property does CouchDB guarantee at the document level?
Explanation: CouchDB provides atomicity at the individual document level, ensuring that each document update is atomic and fully applied or not at all. It does not offer database-level isolation or support consistency for operations like joins, which are more typical of relational systems. Durability is part of ACID, but only guaranteeing it during replication is inaccurate.
What is the primary purpose of replication in CouchDB's architecture?
Explanation: Replication in CouchDB is mainly used to synchronize data between databases located on different servers or devices, supporting distributed data consistency. While security and backups are important, they are not the main goals of replication. Memory optimization is also unrelated.
Which consistency model does CouchDB primarily employ in a distributed environment?
Explanation: CouchDB uses eventual consistency by default, meaning all replicas will eventuallly synchronize but may show temporary differences. Strong and immediate consistency guarantee up-to-date reads, which is not default for CouchDB. Strict two-phase commit is not a part of its design.
Which of the following describes CouchDB's replication model?
Explanation: CouchDB supports master-master replication, which allows any database node to accept writes and synchronize those changes. Single-master setups have only one writable node. Sharding and centralized replication describe other architectures and do not match CouchDB's multi-node write capability.
When two different updates are made to the same document on different CouchDB nodes before synchronization, what is this situation called?
Explanation: This scenario is called a conflict, which occurs because CouchDB allows updates on multiple nodes and synchronizes them later. Joins relate to combining data from multiple tables, which does not apply here. Triggers and checkpoints have different meanings in database systems.
How does CouchDB track changes made to each document?
Explanation: CouchDB tracks each change to a document using revision numbers, allowing the system to manage versions and resolve conflicts. File timestamps and user session states are not part of CouchDB’s versioning mechanism. Primary keys are used for identification, not for tracking changes.
Which statement best describes how CouchDB handles document schemas?
Explanation: CouchDB is schema-less, allowing each document to have its own structure based on application needs. It does not enforce strict or unchanging schemas across all documents. Documents sharing a single fixed schema is a feature of traditional relational databases, not document-based ones.