Choosing Index Types | Dataford Interview Questions

Explain the concept of database indexing and when you would use a composite index versus a single-column index.

Discuss the trade-offs involving query predicates, column order, selectivity, sorting, and write overhead. Use the provided PostgreSQL tables to demonstrate appropriate index definitions and a representative filtered query.

Output

Return organization_id, response_id, and submitted_at.
Include completed responses for organization 101 during January 2025.
Order by submitted_at ascending, then response_id ascending.

Schema

organizations

Column	Type	Description
organization_idPK	INT	Unique organization identifier
organization_name	VARCHAR(100)	Organization display name

survey_responses

Column	Type	Description
response_idPK	INT	Unique survey response identifier
organization_id	INT	Organization associated with the response
submitted_at	TIMESTAMP	Response submission timestamp
response_status	VARCHAR(20)	Processing status of the response
channel	VARCHAR(30)	Submission channel

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Problem