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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.
If any of these limits present a problem for your organization, please contact Atlas support.
Shards in Single-region clusters
Total Nodes per Region of a Multi-Region Cluster
Electable Nodes per Region
Config Server Tier (minimum and maximum)
Connection Limits and Cluster Tier¶
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.
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.
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.
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:
5,000 collections and indexes
M20 / M30
10,000 collections and indexes
100,000 collections and indexes
Organization and Project Limits¶
Database Users per Atlas Project
Atlas Users per Atlas Project
Atlas Users per Atlas Organization
API Keys per Atlas Organization
Access List Entries per Atlas Project
Users per Atlas Team
Teams per Atlas Project
Teams per Atlas Organization
Teams per Atlas User
Organizations per Atlas User
Clusters per Atlas Project
Projects per Atlas Organization
Custom MongoDB roles per Atlas Project
Assigned Roles per Database User
Hourly Billing per Atlas Project
A Technical Account Manager or Billing Admin can raise this limit.
Data Lake Tenants per Atlas User
Total Network Peering Connections per Atlas Project
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
AWS PrivateLink Addressable Targets per Region
Azure Private Link Addressable Targets per Region
Atlas also limits how long particular labels of components can be.
Character Length Limit
Atlas truncates the cluster name to 23 characters in its internal interactions. In practice, this means:
Latin alphanumeric characters only.
API Key Description
Database User Privilege Limits¶
To learn more about unsupported commands, see the unsupported commands for free or shared clusers, paid clusters, and serverless instances
Serverless Instance Limits¶
Serverless instances have different limitations. To learn more, see Serverless Instance Limitations.