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Query Optimization for High Volume
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Query Optimization for High Volume

MediumSQL · PostgreSQL

Problem

How would you approach query optimization for high-volume datasets?

For this exercise, write an optimized PostgreSQL query over the supplied tables. Include only active accounts, active usage event types, processed events, and events occurring during January 2026.

Output

  1. One row per qualifying account and event date.
  2. Columns: event_date, account_id, account_name, event_count, and total_duration_seconds.
  3. Sort by event_date ascending, then account_id ascending.

Schema

accounts
ColumnTypeDescription
account_idPKINTAccount identifier
account_nameVARCHAR(100)Account display name
account_statusVARCHAR(20)Current account status
event_types
ColumnTypeDescription
event_type_idPKINTEvent type identifier
event_type_nameVARCHAR(80)Event type name
categoryVARCHAR(40)Event type category
is_activeBOOLEANWhether the event type is active
activity_events
ColumnTypeDescription
event_idPKBIGINTEvent identifier
account_idINTRelated account identifier
event_type_idINTRelated event type identifier
occurred_atTIMESTAMPTZEvent timestamp
event_statusVARCHAR(20)Processing status
duration_secondsINTEvent duration in seconds
Tablesaccountsevent_typesactivity_events
Interviewer

Your question is Query Optimization for High Volume. Start with the requirements and the three tables in the Question tab.

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