Atlas Limitations¶

Atlas limits how many of each kind of component you can create, and the number of connections allowed to a cluster 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.

Cluster Limits¶

Component	Limit
Shards in Multi-Region Clusters	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`

Connection Limits and Cluster Tier¶

Atlas sets the limits for concurrent incoming connections based on the cluster tier and class:

Cluster Tier	Maximum Connections
`M0`	500
`M2`	500
`M5`	500
`M10`	1500
`M20`	3000
`M30`	3000
`M40`	6000
`M50`	16000
`M60`	32000
`M80`	64000
`M140`	96000
`M200`	128000
`M300`	128000

Note

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

Collection and Index Limits¶

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

Organization and Project Limits¶

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

Label Limits¶

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

Database User Privilege Limits¶

Atlas limits the privilege actions available from the built-in database user privileges.

Example

The killAllSessions command requires the killAnySession privilege. The built-in database user privileges do not include killAnySession.

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

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