MariaDB Interview Questions and Answers for 5 years experience

1. What is MariaDB and how does it differ from MySQL?

   • Answer: MariaDB is a community-developed, open-source relational database management system (RDBMS). It's a fork of MySQL, offering many of the same features but with some key differences. These include improved performance in certain areas, enhanced storage engines (like Aria and InnoDB), and support for newer features faster than MySQL sometimes does. It generally boasts better compatibility with various platforms and often includes additional functionalities.

2. Explain different storage engines in MariaDB and their use cases.

   • Answer: MariaDB offers several storage engines, each with strengths and weaknesses: InnoDB (supports transactions, ACID properties, row-level locking – ideal for most applications), MyISAM (faster for read-heavy workloads but doesn't support transactions – suitable for data warehousing or read-only applications), Aria (a transactional engine that's a blend of InnoDB and MyISAM, a good alternative to InnoDB), and Memory (stores data in RAM, very fast but volatile – suitable for caching).

3. What are indexes in MariaDB and why are they important?

   • Answer: Indexes are special lookup tables that the database search engine can use to speed up data retrieval. Simply put, an index in MariaDB is a pointer to data in a table. They significantly improve query performance by reducing the time it takes to locate specific rows. Different types of indexes exist (B-tree, hash, fulltext), each optimized for various query patterns.

4. Explain the concept of transactions in MariaDB and ACID properties.

   • Answer: A transaction is a sequence of database operations performed as a single logical unit of work. ACID properties ensure data integrity: Atomicity (all or nothing), Consistency (data remains valid), Isolation (concurrent transactions don't interfere), Durability (committed transactions survive crashes).

5. How do you handle deadlocks in MariaDB?

   • Answer: Deadlocks occur when two or more transactions are blocked indefinitely, waiting for each other to release locks. Strategies for handling deadlocks include: proper database design to minimize contention, using shorter transactions, setting a timeout for transactions, and using appropriate isolation levels (e.g., repeatable read).

6. Describe different types of joins in MariaDB with examples.

   • Answer: MariaDB supports various JOIN types: INNER JOIN (returns rows only when there is a match in both tables), LEFT JOIN (returns all rows from the left table, even if there's no match in the right), RIGHT JOIN (returns all rows from the right table, even if there's no match in the left), FULL OUTER JOIN (returns all rows from both tables), and CROSS JOIN (returns the Cartesian product of the tables).

7. Explain the use of stored procedures in MariaDB.

   • Answer: Stored procedures are pre-compiled SQL code stored in the database. They improve performance by reducing network traffic and offer better security by encapsulating business logic. They promote code reusability and maintainability.

8. What are triggers in MariaDB and how are they used?

   • Answer: Triggers are stored programs automatically executed in response to certain events on a particular table or view (e.g., INSERT, UPDATE, DELETE). They're useful for enforcing data integrity, auditing changes, and implementing complex business rules.

9. How do you optimize queries in MariaDB?

   • Answer: Query optimization involves several techniques: using appropriate indexes, avoiding `SELECT *`, writing efficient SQL (using joins effectively, minimizing subqueries), analyzing query execution plans using `EXPLAIN`, and optimizing database design.

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