You Need a Persistent and Durable Storage to Trace Call

question 610

Multiple Choice

You need a persistent and durable storage to trace call activity of an IVR (Interactive Voice Response) system. Call duration is mostly in the 2-3 minutes timeframe. Each traced call can be either active or terminated. An external application needs to know each minute the list of currently active calls. Usually there are a few calls/second, but once per month there is a periodic peak up to 1000 calls/second for a few hours. The system is open 24/7 and any downtime should be avoided. Historical data is periodically archived to files. Cost saving is a priority for this project. What database implementation would better fit this scenario, keeping costs as low as possible?

• A) Use DynamoDB with a "Calls" table and a Global Secondary Index on a "State" attribute that can equal to "active" or "terminated". In this way the Global Secondary Index can be used for all items in the table.
• B) Use RDS Multi-AZ with a "CALLS" table and an indexed "STATE" field that can be equal to "ACTIVE" or 'TERMINATED". In this way the SQL query is optimized by the use of the Index.
• C) Use RDS Multi-AZ with two tables, one for "ACTIVE_CALLS" and one for "TERMINATED_CALLS". In this way the "ACTIVE_CALLS" table is always small and effective to access.
• D) Use DynamoDB with a "Calls" table and a Global Secondary Index on a "IsActive" attribute that is present for active calls only. In this way the Global Secondary Index is sparse and more effective.

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