What is the limit of collection in Azure Cosmos DB for MongoDB (vCore) ?

Question

What is the limit of collection in Azure Cosmos DB for MongoDB (vCore) ?

Hugo MENDES ADMAZ 0

According to the official documentation for Azure Cosmos DB for MongoDB vCore (https://learn.microsoft.com/en-us/azure/cosmos-db/mongodb/vcore/limits), there is a stated limit of 1000 collection per cluster. However, in my current setup (Cluster tier : M30 tier, 2 vCores, 8 GiB RAM), I have successfully created 1500 collections, and the system has not raised any errors or performance issues (so far).

This seems to contradict the documented limitation, so I’m wondering:

What is the actual limit on the number of collections per cluster in MongoDB vCore?

Is the 1000 collection limit outdated or lifted dynamically ?

And should I expect any performance or stability issues if I continue creating more collections?

Saraswathi Devadula 1,945 Reputation points Microsoft External Staff

2025-04-10T09:03:21.8366667+00:00

Hello Hugo MENDES ADMAZ

I understand that you want to know about the collections of the Azure CosmosDB for MongoDB(vCore) per cluster.

We are reaching out to the internal team to get more information related to your query and will get back to you as soon as we have an update.

Appreciate your time and patience while working with us on this request.
Oury Ba-MSFT 20,716 Reputation points Microsoft Employee

2025-04-21T22:33:46.5366667+00:00

@Hugo MENDES ADMAZ Thank you for reaching out.

This makes sense since the collection count limit in Mongo vCore is a best practice recommendation, not a hard limit. We will reevaluate this to avoid confusion.

1 answer

Your answer

Saraswathi Devadula 1,945 Reputation points Microsoft External Staff

2025-04-10T09:03:21.8366667+00:00

Hello Hugo MENDES ADMAZ

I understand that you want to know about the collections of the Azure CosmosDB for MongoDB(vCore) per cluster.

We are reaching out to the internal team to get more information related to your query and will get back to you as soon as we have an update.

Appreciate your time and patience while working with us on this request.
Oury Ba-MSFT 20,716 Reputation points Microsoft Employee

2025-04-21T22:33:46.5366667+00:00

@Hugo MENDES ADMAZ Thank you for reaching out.

This makes sense since the collection count limit in Mongo vCore is a best practice recommendation, not a hard limit. We will reevaluate this to avoid confusion.

Answer 1

HI Hugo MENDES ADMAZ,
The documented limit of 1000 collections per cluster in Azure Cosmos DB for MongoDB vCore is a general guideline rather than a strict enforcement. Here's what you need to know:

1. Actual Limit

While the documentation states a limit of 1000 collections, your ability to create 1500 collections without errors suggests that the limit may be dynamically adjusted based on your cluster tier and workload.
- Azure Cosmos DB is designed to be flexible, and some limits may evolve over time as the service improves.

2. Outdated or Dynamic Limit

The 1000 collection limit might be outdated or not strictly enforced for certain configurations. It's possible that higher-tier clusters (like M30) allow more collections due to increased resources.

3. Performance and Stability Considerations

Exceeding the recommended limit could lead to:
- Increased latency for queries and operations.
- Higher memory and CPU usage, especially if collections have large indexes or frequent transactions.
- Challenges with scaling or managing the cluster.
Monitor your cluster's metrics (e.g., CPU, memory, and throughput) to ensure stability as you add more collections.

Recommendations:

Monitor Performance: Use Azure Monitor to track resource utilization and identify bottlenecks.
Plan for Scaling: If you anticipate needing more collections, consider upgrading to a higher-tier cluster or exploring sharding strategies.

I would request you to refer the below mentioned links for more information
1.Service Limits in Azure Cosmos DB for MongoDB vCore
2.Azure Cosmos DB service quotas
3.MicrososftDoc
I hope this information helps. Please do let us know if you have any further queries. 

Adithya Prasad K 740 Reputation points Microsoft External Staff

2025-04-11T17:36:21.5466667+00:00

Hi Hugo MENDES ADMAZ,
Hope this helps. Do let us know if you any further queries. -If this answers your query, do click Accept Answer and Yes for was this answer helpful. And, if you have any further query do let us know.
Adithya Prasad K 740 Reputation points Microsoft External Staff

2025-04-12T01:09:49.65+00:00

Hi Hugo MENDES ADMAZ, Hope this helps. Do let us know if you any further queries. -If this answers your query, do click Accept Answer and Yes for was this answer helpful. And, if you have any further query do let us know.

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What is the limit of collection in Azure Cosmos DB for MongoDB (vCore) ?

1 answer

1. Actual Limit

2. Outdated or Dynamic Limit

3. Performance and Stability Considerations

Recommendations:

Your answer