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Atlas Limitations

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  • Cluster Limits
  • Connection Limits and Cluster Tier
  • Collection and Index Limits
  • Organization and Project Limits
  • Label Limits
  • Database User Privilege Limits
  • Serverless Instance Limits

Atlas limits how many of each kind of component you can create, and the number of connections allowed to a database deployments. For clusters, the number of connections allowed is based on cluster tier. These tables outline component and connection limits.

Important

If any of these limits present a problem for your organization, please contact Atlas support.

Component
Limit
12
Shards in Single-region clusters
50
Total Nodes per Region of a Multi-Region Cluster
40
Electable Nodes per Region
7
Config Server Tier (minimum and maximum)
M30

Atlas sets the limits for concurrent incoming connections based on the cluster tier and class. Atlas connection limits apply per node. For sharded clusters, Atlas connection limits apply per mongos router. The number of mongos routers is equal to the number of replica set nodes across all shards.

Your read preference also contributes to the total number of connections Atlas can allocate for a given query.

Example

Your M2 cluster has three nodes with a 500 connection limit per node. Atlas reserves 10 connections per node. If you set your read preference to secondary, Atlas can read from the two secondary nodes for a combined 980 connection limit.

Note

Atlas reserves a small number of connections to each Atlas cluster for supporting Atlas services. Contact Atlas support for more information on Atlas reserved connections.

While there is no hard limit on the number of collections in a single cluster, the performance of a cluster might degrade if it serves a large number of collections and indexes. Larger collections have a greater impact on performance.

The recommended maximum combined number of collections and indexes by Atlas cluster tier are as follows:

Cluster tier
Recommended maximum
M10
5,000 collections and indexes
M20 / M30
10,000 collections and indexes
M40+
100,000 collections and indexes
Component
Limit
Database Users per Atlas Project
100
Atlas Users per Atlas Project
500
Atlas Users per Atlas Organization
500
API Keys per Atlas Organization
500
Access List Entries per Atlas Project
200
Users per Atlas Team
250
Teams per Atlas Project
100
Teams per Atlas Organization
250
Teams per Atlas User
100
Organizations per Atlas User
250
Clusters per Atlas Project
25
Projects per Atlas Organization
250
Custom MongoDB roles per Atlas Project
100
Assigned Roles per Database User
100
Hourly Billing per Atlas Project

$50

Note

A Technical Account Manager or Billing Admin can raise this limit.

Data Lake Tenants per Atlas User
25
Total Network Peering Connections per Atlas Project

50

Note

Atlas limits the number of nodes per Network Peering connection based on the CIDR block and the region selected for the project.

Pending Network Peering Connections per Atlas Project
25
AWS PrivateLink Addressable Targets per Region
50
Azure Private Link Addressable Targets per Region
150

Atlas also limits how long particular labels of components can be.

Component
Character Length Limit
Cluster Name

64

Important

Atlas truncates the cluster name to 23 characters in its internal interactions. In practice, this means:

  • Cluster names shorter than 23 characters can't end with hyphen or dash (-).
  • Cluster names 23 characters or longer can't use a hyphen or dash (-) as its 23rd character.
  • The first 23 characters in a cluster name must be unique within a project.
Project Name
64
Organization Name

64

Latin alphanumeric characters only.

API Key Description
250

To learn more about unsupported commands, see the unsupported commands for free or shared clusers, paid clusters, and serverless instances

Serverless instances have different limitations. To learn more, see Serverless Instance Limitations.

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