Mastering Database Fundamentals for Product-Based Companies

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You Should Know:

1. Database Fundamentals & Architecture:

  • Understand the types of databases: Relational (SQL) and NoSQL.
  • Learn about ACID properties and the CAP theorem.
  • Differentiate between DBMS, RDBMS, and NoSQL.
  • Explore storage engines like InnoDB and MyISAM.
  • Study database architectures: Single-tier, Two-tier, and Three-tier.

Commands:

SHOW ENGINES; -- Displays storage engines available in MySQL.
SELECT * FROM information_schema.engines; -- Lists all storage engines.

2. Indexing & Query Optimization:

  • Learn about different types of indexes: Clustered, Non-clustered, Composite, Unique, Full-text, and Bitmap.
  • Understand how indexing works using B-Trees and Hash Indexing.
  • Use `EXPLAIN ANALYZE` to understand query execution plans.
  • Optimize joins, sorting, and aggregations.

Commands:

CREATE INDEX idx_name ON table_name(column_name); -- Creates an index.
EXPLAIN SELECT * FROM table_name WHERE condition; -- Analyzes query execution.

3. Transactions & Concurrency Control:

  • Ensure data consistency with ACID properties.
  • Understand transaction isolation levels: READ COMMITTED, REPEATABLE READ, and SERIALIZABLE.
  • Learn about locking mechanisms: Pessimistic vs. Optimistic.
  • Prevent deadlocks and understand Multi-Version Concurrency Control (MVCC).

Commands:

START TRANSACTION; -- Begins a transaction.
COMMIT; -- Commits the transaction.
ROLLBACK; -- Rolls back the transaction.

4. Database Partitioning & Sharding:

  • Scale databases using horizontal and vertical partitioning.
  • Implement range, list, hash, and composite partitioning.
  • Understand sharding strategies: Key-based, Range-based, and Directory-based.
  • Compare replication vs. sharding.

Commands:

CREATE TABLE partitioned_table (
id INT,
data VARCHAR(100)
PARTITION BY RANGE (id) (
PARTITION p0 VALUES LESS THAN (100),
PARTITION p1 VALUES LESS THAN (200)
); -- Creates a partitioned table.

5. Data Modeling & Normalization:

  • Design efficient schemas using Entity-Relationship (ER) Modeling.
  • Normalize databases up to 5NF.
  • Understand denormalization and when to use it.
  • Compare Star vs. Snowflake Schema in data warehousing.

Commands:

ALTER TABLE table_name ADD CONSTRAINT pk_name PRIMARY KEY (column_name); -- Adds a primary key.

6. SQL Query Performance Tuning:

  • Write efficient SQL queries.
  • Avoid full table scans by using proper indexing.
  • Use materialized views and caching for performance.

Commands:

CREATE MATERIALIZED VIEW mv_name AS SELECT * FROM table_name; -- Creates a materialized view.
  1. NoSQL vs. SQL – When to Use What?

– Choose between SQL and NoSQL based on use cases.
– Understand the CAP theorem and BASE properties in NoSQL.
– Explore NoSQL databases like MongoDB, Cassandra, and DynamoDB.

Commands:

mongo --host localhost --port 27017 --username user --password pass --authenticationDatabase admin

What Undercode Say:

Mastering database fundamentals is crucial for excelling in product-based company interviews. Focus on understanding database architecture, indexing, query optimization, transactions, and partitioning. Practice SQL and NoSQL commands to enhance your skills. Use tools like `EXPLAIN ANALYZE` for query optimization and explore different database engines and architectures. Strengthen your knowledge of data modeling and normalization to design efficient schemas. Finally, understand when to use SQL vs. NoSQL based on the specific requirements of your project.

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