MAP data type for key-value pairs

Concepts covered: sqlMapBasic

Creating Maps Accessing Map Values When to Use Maps Bracket notation on a MAP column provides O(1) hash-based access, making it fast regardless of how many keys the map contains. Maps are ideal for sparse data where each row may have different attributes, avoiding the need for many nullable columns.

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This section is part of the Data Types: Advanced lesson on DataDriven, a free data engineering interview prep platform. Each section includes explanations, worked examples, and hands-on code challenges that execute in real time. SQL queries run against a live PostgreSQL database. Python runs in a sandboxed Docker container. Data modeling problems validate against interactive schema canvases. All content is framed around what data engineering interviewers actually test at companies like Meta, Google, Amazon, Netflix, Stripe, and Databricks.

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