Unused DynamoDB GSI costs: what engineering teams should review
A short technical guide to unused DynamoDB GSI costs, index review workflows, and safe optimization steps.
Short answer
Unused DynamoDB GSIs can cost money through storage and write maintenance even when application reads no longer use them. Review usage, dependencies, projections, and write paths before changing indexes.
- Review read activity and dependency risk.
- Check write-heavy tables and projection size.
- Treat deletion as an engineering change, not an automatic cleanup.
Why unused GSIs happen
Feature changes, migrations, and emergency fixes can leave old access paths behind. A GSI that once mattered may become stale while still adding cost.
What to check before removing an index
Review read activity, application dependencies, scheduled jobs, backfills, dashboards, and rollback paths before removing a global secondary index.
How Dynasight helps
Dynasight flags unused and underused GSI candidates with table context so teams can prioritize index reviews.
FAQ
Common questions
Can I delete an unused GSI immediately?
Not safely without dependency review. Dynasight identifies candidates, but your team should verify application usage first.
Do GSIs affect write cost?
Yes. DynamoDB maintains index data as table data changes, so write-heavy tables can pay for GSI maintenance.
What is the safest first step?
Create an index review ticket with usage evidence, owners, dependencies, and rollback considerations.
Keep exploring
Related DynamoDB optimization topics
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