Classplus Software Engineer Interview Questions and Answers

Developed a mobile app for tracking personal fitness goals

• Used React Native to create a cross-platform app

• Implemented features such as goal setting, progress tracking, and workout logging

• Integrated with wearable devices like Fitbit for automatic data syncing

Ways to speed up SQL queries in increasing order of complexity

• Use indexes on columns frequently used in WHERE clauses

• Optimize queries by avoiding unnecessary joins and subqueries

• Use stored procedures to reduce network traffic and improve performance

• Consider denormalizing tables for frequently accessed data

• Use query optimization techniques like query caching and query hints

Redis is single-threaded.

• Redis is single-threaded, meaning it can only execute one command at a time.

• This design choice allows Redis to be extremely fast and efficient for certain use cases.

• However, it also means that Redis may not be the best choice for highly concurrent workloads.

Data types that can be used as keys in Python include strings, integers, floats, tuples, and custom objects.

• Strings are commonly used as keys in Python dictionaries.

• Integers and floats can also be used as keys.

• Tuples can be used as keys if they only contain immutable elements.

• Custom objects can be used as keys if they are hashable.

• Examples: {'name': 'John'}, {1: 'apple'}, {(1, 2): 'tuple'}

Types of indexing in SQL include clustered, non-clustered, unique, and composite indexes.

• Clustered index physically reorders the table based on the index key

• Non-clustered index creates a separate structure for the index

• Unique index ensures that all values in the index column are unique

• Composite index uses multiple columns for indexing