Realm vs SQLite: Key Differences Quiz Quiz

Discover essential distinctions between Realm and SQLite with this quick quiz. Enhance your understanding of how these two popular mobile database solutions differ in architecture, data handling, and performance.

1. Database Architecture

   Which statement best describes the underlying architecture of Realm compared to SQLite?

   1. Realm relies on flat files whereas SQLite only works with cloud storage.
   2. Realm uses an object-oriented model while SQLite uses a relational model.
   3. Realm is a relational database, and SQLite is a graph database.
   4. Realm uses key-value pairs exclusively unlike SQLite.

   Explanation: Realm is based on an object-oriented design, allowing data to be stored as objects, whereas SQLite uses a traditional relational model with tables, rows, and columns. Flat files and cloud storage are not defining traits that separate the two. SQLite is not a graph database, and both databases are more than just key-value stores.

2. Data Access Methods

   When fetching data, how does Realm's query mechanism mainly differ from that of SQLite?

   1. Realm does not allow querying at all, unlike SQLite.
   2. Realm needs command-line queries, but SQLite uses visual tools exclusively.
   3. Realm offers object-based queries, while SQLite uses SQL statements.
   4. Realm only supports NoSQL queries, while SQLite requires XML.

   Explanation: Realm allows queries to be performed using its object-based API, making it convenient for object-oriented languages. SQLite, on the other hand, utilizes standard SQL statements for data access. Realm does not use NoSQL or XML queries, and both provide visual tools and support query functionality.

3. Schema Definition

   How is schema management typically handled in Realm compared to SQLite?

   1. Realm does not require a schema, whereas SQLite does.
   2. Realm updates schemas with HTML files only, while SQLite uses JSON.
   3. Realm and SQLite both use only CSV files for schema.
   4. Realm manages schemas through classes, while SQLite uses SQL schema scripts.

   Explanation: With Realm, schemas are usually defined by creating classes that represent data models, while SQLite's schema is set up and managed through SQL statements such as CREATE TABLE scripts. Realm does not use HTML or JSON files by default for schema, and neither database manages schema with only CSV files.

4. Data Relationships

   Which of the following describes how relationships between data entities are typically handled in Realm compared to SQLite?

   1. Realm uses only array indexes; SQLite uses document links.
   2. Realm uses direct object references; SQLite uses foreign keys.
   3. Realm relies on primary keys alone; SQLite uses secondary keys.
   4. Both use exactly the same relationship mechanism.

   Explanation: Realm allows direct object references to establish relationships, making navigation simple, while SQLite utilizes foreign keys to represent relationships between tables. Arrays and document links are not exclusive features here, and while both use keys, their approach to relationships is quite different.

5. Performance Considerations

   In terms of general performance for read and write operations, how is Realm often compared to SQLite when handling complex queries in mobile apps?

   1. Both have identical performance as they use the same engine.
   2. Realm is slower because it only supports batch processing.
   3. SQLite is always faster because it stores data in plain text.
   4. Realm often demonstrates faster read/write speed due to its object storage engine.

   Explanation: Realm's underlying engine allows for efficient object storage and faster access in many scenarios. SQLite, while efficient, stores data in a relational format and does not use plain text, so it is not always faster. Batch processing is not a requirement unique to Realm, and the engines are distinct, so performance is not identical.

6. Transactions and Threading

   How does transaction support and threading in Realm differ from that in SQLite?

   1. Realm does not support transactions but SQLite does.
   2. Realm and SQLite both prohibit transactions entirely.
   3. Realm includes built-in support for multithreaded transactions, while SQLite offers more manual transaction control.
   4. SQLite automatically runs all operations in separate threads unlike Realm.

   Explanation: Realm is designed to handle multithreaded operations smoothly, supporting object-based transactions natively. SQLite supports transactions but usually requires more explicit management by the developer. Both databases support transactions, and neither prohibits them or runs everything automatically in separate threads.

7. Use Case Suitability

   For which usage scenario is SQLite typically preferred over Realm?

   1. When storing media files directly in the database.
   2. When only key-value data needs to be stored.
   3. When compatibility with existing SQL-based systems and migration scripts is important.
   4. When the primary need is for document-based storage.

   Explanation: SQLite's widespread adoption and SQL compatibility make it preferable for use cases involving existing scripts or integration with other SQL-based systems. Key-value storage and document-based storage are not the main strengths of SQLite or Realm, and neither database is designed for storing large media files directly.

8. Mobile Platform Support

   What is a primary difference in mobile platform support between Realm and SQLite?

   1. Realm offers built-in support for object models on both iOS and Android.
   2. SQLite is exclusive to web-based applications.
   3. Realm does not support Android devices at all.
   4. SQLite only works on desktop platforms.

   Explanation: Realm offers native object model support, making it easy to use in both major mobile operating systems. SQLite works well on mobile platforms and is not limited to desktops, nor is it exclusive to web applications. Realm does indeed support Android, so the incorrect options are not accurate.

9. Migration Complexity

   How does the process of migrating database structures generally compare between Realm and SQLite?

   1. Realm migrations need binary patching; SQLite does not support migrations.
   2. SQLite automates all migrations seamlessly, Realm does not allow migrations.
   3. Both only support exporting to Excel for migration.
   4. Realm usually automates migrations, while SQLite requires manual SQL migration scripts.

   Explanation: Realm provides automated migration tools to ease the schema evolution process, while SQLite often needs you to write SQL migration scripts manually. Neither database is restricted to Excel for migrations or relies on binary patching. Realm and SQLite both support structured migrations, but their methods differ.

10. Data Size Limitation

    Regarding maximum database file size, which option best describes the typical limitation for both Realm and SQLite?

    1. Both can handle large files, with limits generally beyond typical mobile needs.
    2. Realm and SQLite only support in-memory storage, not files.
    3. SQLite does not permit files larger than 1GB, Realm only 512MB.
    4. Realm files are limited to less than 10MB, while SQLite can be unlimited.

    Explanation: Both database systems can handle files much larger than what most mobile apps require. Specific file size limits are high enough (often in terabytes) that they rarely become a mobile bottleneck. The other options exaggerate the limitations or are incorrect about storage modes.