Hello @Ashok Arumugam , Thank you for posting your question in the Microsoft Q&A forum.
We understand that you need help identifying heavily used databases and collections in Azure Cosmos DB using the Mongo API via the Azure Portal. To assist you, you can monitor the performance metrics and activity logs. I will walk you through a solution with step-by-step instructions, along with helpful documentation links for more detailed guidance.
- Sign in to the Azure portal and navigate to your Azure Cosmos DB account.
- You can view your account metrics either from the Metrics pane or the Insights pane.
- Metrics: This pane provides numerical metrics that are collected at regular intervals and describes some aspect of a system at a particular time. For example, you can view and monitor the server side latency metric, normalized request unit usage metric, etc.
- Insights: This pane provides a customized monitoring experience for Azure Cosmos DB. Insights use the same metrics and logs that are collected in Azure Monitor and show an aggregated view for your account.
- Open the Insights pane. By default, the Insights pane shows the throughput, requests, storage, availability, latency, system, and management operations metrics for every container in your account. You can select the Time Range, Database, and Container for which you want to view insights. The Overview tab shows RU/s usage, data usage, index usage, throttled requests, and normalized RU/s consumption for the selected database and container.
The following metrics are available from the Insights pane:
- Throughput. This tab shows the total number of request units consumed or failed (429 response code) because the throughput or storage capacity provisioned for the container has exceeded.
- Requests. This tab shows the total number of requests processed by status code, by operation type, and the count of failed requests (429 response code). Requests fail when the throughput or storage capacity provisioned for the container exceeds.
- Storage. This tab shows the size of data and index usage over the selected time period.
- Availability. This tab shows the percentage of successful requests over the total requests per hour. The Azure Cosmos DB SLAs defines the success rate.
- Latency. This tab shows the read and write latency observed by Azure Cosmos DB in the region where your account is operating. You can visualize latency across regions for a geo-replicated account. You can also view server-side latency by different operations. This metric doesn't represent the end-to-end request latency.
- System. This tab shows how many metadata requests that the primary partition serves. It also helps to identify the throttled requests.
- Management Operations. This tab shows the metrics for account management activities such as account creation, deletion, key updates, network and replication settings.
Please refer to the below mentioned links for more information. Monitor Azure Cosmos DB with Azure Monitor Azure Cosmos DB insights | Microsoft Learn
I hope this information helps. Please do let us know if you have any further queries.