MariaDB Interview Questions and Answers for 7 years experience

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MariaDB Interview Questions and Answers (7 Years Experience)

  1. What is the difference between InnoDB and MyISAM storage engines?

    • Answer: InnoDB supports transactions, row-level locking, and foreign keys, making it suitable for applications requiring data integrity. MyISAM is faster for read operations but lacks these features, making it better for read-heavy workloads where data integrity is less critical. InnoDB uses clustered indexes, while MyISAM uses non-clustered indexes. InnoDB has better support for concurrent access and recovery from crashes.

  2. Explain the concept of indexing in MariaDB. What are different types of indexes?

    • Answer: Indexing speeds up data retrieval by creating a separate data structure that points to rows in the table. Different types include B-tree (most common, for equality and range searches), fulltext (for searching text), hash (for equality searches only), spatial (for geographic data), and unique indexes (ensuring uniqueness of values).

  3. How do you optimize MariaDB queries for performance?

    • Answer: Optimization involves using appropriate indexes, writing efficient SQL queries (avoiding `SELECT *`), analyzing query execution plans using `EXPLAIN`, optimizing table structures, using query caching, and tuning server parameters like buffer pool size and innodb_buffer_pool_size.

  4. What are transactions and their ACID properties?

    • Answer: Transactions are a sequence of operations treated 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), and Durability (changes persist even after crashes).

  5. Explain different transaction isolation levels.

    • Answer: Read Uncommitted (dirty reads possible), Read Committed (prevents dirty reads), Repeatable Read (prevents dirty reads and non-repeatable reads), Serializable (highest isolation, prevents phantom reads).

  6. How do you handle deadlocks in MariaDB?

    • Answer: Deadlocks occur when two or more transactions are blocked indefinitely, waiting for each other. Solutions involve optimizing queries to minimize locking time, using shorter transactions, and adjusting the transaction isolation level. MariaDB provides tools to detect and resolve deadlocks, often automatically rolling back one of the transactions.

  7. What are stored procedures and their benefits?

    • Answer: Stored procedures are pre-compiled SQL code stored in the database. Benefits include improved performance, reduced network traffic, enhanced security (by controlling access), and improved code reusability.

  8. Explain the use of triggers in MariaDB.

    • Answer: Triggers are stored procedures automatically executed in response to certain events on a particular table (like INSERT, UPDATE, DELETE). They are used for enforcing data integrity, auditing changes, and implementing complex business logic.

  9. How do you manage user accounts and permissions in MariaDB?

    • Answer: Using the `CREATE USER`, `GRANT`, and `REVOKE` statements. Users are assigned privileges to specific databases and tables (SELECT, INSERT, UPDATE, DELETE, etc.). Role-based access control can simplify permission management.

  10. What are views in MariaDB and how are they useful?

    • Answer: Views are virtual tables based on the result-set of an SQL statement. They simplify complex queries, provide a customized view of data, and enhance security by restricting access to underlying tables.

  11. Explain MariaDB's replication mechanism.

    • Answer: MariaDB supports various replication methods, including master-slave (one master, multiple slaves), and more complex setups like multi-source replication and group replication. Replication ensures high availability and data redundancy.

  12. How do you perform backups and restores in MariaDB?

    • Answer: Methods include logical backups (using `mysqldump`), physical backups (copying data files), and using point-in-time recovery with binary logs. The choice depends on requirements for recovery time and data consistency.

  13. Describe your experience with MariaDB performance tuning and optimization. Give specific examples.

    • Answer: [Provide a detailed answer based on personal experience. This should include specific examples of performance bottlenecks encountered, the methods used to identify the root cause, and the solutions implemented. Mention tools used like `pt-query-digest`, `percona-toolkit`, etc.]

  14. What are your experiences with MariaDB clustering?

    • Answer: [Describe experience with MariaDB Galera Cluster or other clustering solutions. Mention setup, configuration, and challenges faced. This should demonstrate a solid understanding of high availability concepts.]

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