In Cosmos DB Monitoring Insights (Preview) what is the __empty collection?

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In Cosmos DB Monitoring Insights (Preview) what is the __empty collection?

JIS-4881 21

I have a Cosmos DB database with multiple containers using shared throughput autoscaling, 400 to max 4000.

In the Monitoring Insights (preview) I noticed higher throughput every hour. I tried finding the container this is for by selecting the throughput tab and setting the database and then trying each container, but I can't see the same pattern as when it is set to unset.

Then at the bottom of the screen I noticed that under Provisioned Throughput (Max) by Collection, it specifies the __empty collection and that has a value of 800.
What is the __empty collection?

Anurag Sharma 17,631 Reputation points

2021-05-25T05:27:19.297+00:00

Hi @JIS-4881 , welcome to Microsoft Q&A forum.

I have reached out to product group for more details on this and will keep the response posted here.
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Anurag Sharma 17,631 Reputation points

2021-05-25T05:27:19.297+00:00

Hi @JIS-4881 , welcome to Microsoft Q&A forum.

I have reached out to product group for more details on this and will keep the response posted here.
Deleted

This comment has been deleted due to a violation of our Code of Conduct. The comment was manually reported or identified through automated detection before action was taken. Please refer to our Code of Conduct for more information.

Answer 1

Anurag Sharma 17,631

Hi @JIS-4881 , thanks for your patience. I have received the reply from the product group. Please find the verbatim below:

"The collection name is set to the empty value when the throughput is shared among collections in a database, i.e. SharedThroughputOffer. When a database is set with the shared throughput offer the metric (i.e. ProvisionedThroughput) is not emitted in the collection level but in the database level, so that the collection name is not available (i.e. “__empty” ) when the customer tries to filter the metric data by collection."

Please let me know if this helps.

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If answer helps, please mark it 'Accept Answer'

Anurag Sharma 17,631 Reputation points

2021-05-28T06:01:44.19+00:00

Hi @JIS-4881 , just wanted to follow up on this thread. Please let us know if you have any follow up questions or the above answer helped.
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Jack Riggle 0 Reputation points

2024-07-31T18:31:09.6833333+00:00

Will the throughput set at a collection level override the throughput set at a database level? In this example __Empty is the database level throughput (according to answer above) and my-collection-1 is the collection level throughput, will my-collection-1 be limited to 1k RUs even though the database is set to 5.4K?
Jack Riggle 0 Reputation points

2024-07-31T19:15:41.7566667+00:00

Follow up
according to this documentation it appears the collection level throughput will override the database level throughput https://learn.microsoft.com/en-us/azure/cosmos-db/set-throughput#set-throughput-on-a-container

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In Cosmos DB Monitoring Insights (Preview) what is the __empty collection?

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