MIJI DApp Server Docs

Atlas M0 (Free Cluster) Limits

Configuration Limits

The following table lists the configuration limits of Atlas M0 Free clusters:

Configuration Option	Limit
Cloud Service Provider and Region	You can deploy `M0` Free clusters only in a subset of regions on AWS (Amazon Web Services), Google Cloud, and Azure (Microsoft Azure). To learn more about supported cloud provider regions for Free clusters, see: - [Amazon Web Services (AWS)](https://mongodbcom-cdn.staging.corp.mongodb.com/docs/atlas/reference/amazon-aws/#std-label-amazon-aws) - [Google Cloud Platform (GCP)](https://mongodbcom-cdn.staging.corp.mongodb.com/docs/atlas/reference/google-gcp/#std-label-google-gcp) - [Microsoft Azure](https://mongodbcom-cdn.staging.corp.mongodb.com/docs/atlas/reference/microsoft-azure/#std-label-microsoft-azure)
MongoDB Version and Storage Engine	Atlas uses MongoDB 8.0 for `M0` clusters.
MongoDB Version Upgrade	You can't upgrade the MongoDB version that `M0` clusters run. Atlas upgrades `M0` Free clusters to the newest MongoDB version after several patch versions become available for that version. To learn more, see [MongoDB Versioning](https://www.mongodb.com/docs/manual/reference/versioning/).
Cluster Tier	You must select the `M0` cluster tier to deploy a Free cluster. You can deploy only one `M0` cluster per project. However if you have sales contracts with MongoDB, you might be able to deploy more `M0` clusters per project. To learn more, contact a MongoDB sales representative.
Cluster Memory	You can't configure memory for `M0` Free clusters.
Cluster Storage	You can't configure storage size for `M0` Free clusters.
Replication Factor	Replication Factor is set to `3 Nodes` and you can't modify it for `M0` Free clusters.
Replica Set Tags	`M0` Free clusters don't have pre-defined [replica set tags](https://mongodbcom-cdn.staging.corp.mongodb.com/docs/atlas/reference/replica-set-tags/#std-label-replica-set-tags).
Do You Want A Sharded Cluster	You can't deploy a `M0` Free cluster as a Sharded Cluster.
Do You Want To Enable Backup	You can't enable backups on `M0` Free clusters. As an alternative to enabling backups, you can use [`mongodump`](https://www.mongodb.com/docs/database-tools/mongodump/#mongodb-binary-bin.mongodump) to back up your data and [`mongorestore`](https://www.mongodb.com/docs/database-tools/mongorestore/#mongodb-binary-bin.mongorestore) to restore that data. To learn how to use these MongoDB command line tools to manually back up your data, see [Connect to a Cluster using Command Line Tools](https://mongodbcom-cdn.staging.corp.mongodb.com/docs/atlas/command-line-tools/).
Test Primary Failovers	You can't perform primary failover testing on `M0` Free clusters.
Simulate Regional Outage	You can't perform regional outage testing on `M0` Free clusters.
Database Auditing	You can't configure [database auditing](https://mongodbcom-cdn.staging.corp.mongodb.com/docs/atlas/database-auditing/#std-label-set-up-database-auditing) on `M0` Free clusters.
Encryption at Rest using your Key Management	You can't configure [encryption at Rest using Customer Key Management](https://mongodbcom-cdn.staging.corp.mongodb.com/docs/atlas/security-kms-encryption/#std-label-security-kms-encryption) on `M0` Free clusters.
Network Peering Connections	You can't configure [network peering connections](https://mongodbcom-cdn.staging.corp.mongodb.com/docs/atlas/security-vpc-peering/#std-label-vpc-peering) on `M0` Free clusters.
Private endpoints	`M0` Free clusters don't support [private endpoints](https://mongodbcom-cdn.staging.corp.mongodb.com/docs/atlas/security-configure-private-endpoints/#std-label-private-endpoint).
Access Tracking	You can't view the database access history for `M0` Free clusters.

Operational Limits

The following table lists the operational limits of Atlas M0 Free clusters:

</table> ## Driver Minimum Requirements

Operation	Limits
[Aggregation](https://www.mongodb.com/docs/manual/aggregation/) and [Queries](https://www.mongodb.com/docs/manual/tutorial/query-documents/)	Atlas `M0` Free clusters and Flex clusters don't support writing temporary files to disk. Atlas ignores the `allowDiskUse` option and the corresponding commands behave as if the `allowDiskUse` option is set to `false`. Aggregation pipelines on `M0` Free clusters can have a maximum of 50 stages. These aggregation pipelines don't support: - [`$currentOp`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/currentOp/#mongodb-pipeline-pipe.-currentOp), [`$listLocalSessions`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/listLocalSessions/#mongodb-pipeline-pipe.-listLocalSessions), [`$listSessions`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/listSessions/#mongodb-pipeline-pipe.-listSessions), and [`$planCacheStats`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/planCacheStats/#mongodb-pipeline-pipe.-planCacheStats) stages. - The [$$USER_ROLES](https://www.mongodb.com/docs/manual/reference/aggregation-variables/#mongodb-variable-variable.USER_ROLES) system variable.
API (Application Programming Interface) Access	While you can create an `M0` Free cluster using the [Clusters](https://www.mongodb.com/docs/api/doc/atlas-admin-api-v2/group/endpoint-clusters) API (Application Programming Interface) resource, you cannot modify an `M0` Free cluster using the [Clusters](https://www.mongodb.com/docs/api/doc/atlas-admin-api-v2/group/endpoint-clusters) API (Application Programming Interface) resource. You can create an `M0` Free cluster using the [Clusters](https://www.mongodb.com/docs/api/doc/atlas-admin-api-v2/group/endpoint-clusters) API (Application Programming Interface) resource. You can create one `M0` Free cluster per project. However if you have sales contracts with MongoDB, you might be able to deploy more `M0` clusters per project. To learn more, contact a MongoDB sales representative.
Atlas Alerts	`M0` Free clusters can only trigger alerts configured with one of the following [alert conditions](https://mongodbcom-cdn.staging.corp.mongodb.com/docs/atlas/reference/alert-conditions/): - Connections - Logical Size - Network - Opscounter
Atlas Monitoring	The Metrics view of an `M0` Free cluster displays only the following metrics: - Connections - Logical Size - Network - Opscounter To learn more, see [Real Time Metrics](https://mongodbcom-cdn.staging.corp.mongodb.com/docs/atlas/real-time-performance-panel/#std-label-real-time-metrics-status-tab).
Authentication	`M0` Free clusters support the following authentication methods only: - Password (SCRAM-SHA1) - X.509 Certificates - AWS IAM
Auto-Expand Storage	`M0` Free clusters don't provide [automatically scaling storage](https://mongodbcom-cdn.staging.corp.mongodb.com/docs/atlas/cluster-autoscaling/#std-label-cluster-autoscaling).
BSON (Binary Javascript Object Notation) Nested Object Depth	`M0` Free clusters can store documents with a maximum of 50 nested levels.
Build Index with Rolling Build	`M0` Free clusters don't support [building indexes with a rolling build](https://www.mongodb.com/docs/manual/tutorial/build-indexes-on-replica-sets/).
Change Streams Filtering	For `M0` Free clusters, you can use only strings and regular expressions in filters on database names (namespace `ns` fields) in [change streams](https://www.mongodb.com/docs/manual/changeStreams/). You can't use commands, such as `$in`, in database namespace filters. This limit doesn't apply to filtering on collection names in change streams.
Cluster Persistence	Atlas may deactivate idle `M0` Free clusters as per the [Terms of Service](https://www.mongodb.com/cloud-terms-and-conditions?tck=docs).
Command Line Tools	M0 Free clusters and Flex clusters don't support the following command line tool options: Command Line Tool Unsupported Options [`mongorestore`](https://www.mongodb.com/docs/database-tools/mongorestore/#mongodb-binary-bin.mongorestore) - [--restoreDbUsersAndRoles](https://www.mongodb.com/docs/database-tools/mongorestore/#std-option-mongorestore.--restoreDbUsersAndRoles) - [--oplogReplay](https://www.mongodb.com/docs/database-tools/mongorestore/#std-option-mongorestore.--oplogReplay) - [--preserveUUID](https://www.mongodb.com/docs/database-tools/mongorestore/#std-option-mongorestore.--preserveUUID) [`mongodump`](https://www.mongodb.com/docs/database-tools/mongodump/#mongodb-binary-bin.mongodump) - [--dumpDbUsersAndRoles](https://www.mongodb.com/docs/database-tools/mongodump/#std-option-mongodump.--dumpDbUsersAndRoles) - [--oplog](https://www.mongodb.com/docs/database-tools/mongodump/#std-option-mongodump.--oplog) For `M0` Free clusters, you can't run [`mongorestore`](https://www.mongodb.com/docs/database-tools/mongorestore/#mongodb-binary-bin.mongorestore) or [`mongodump`](https://www.mongodb.com/docs/database-tools/mongodump/#mongodb-binary-bin.mongodump) on the `admin` database. If you use the `--db` option to set the destination database to `admin`, the program returns an error.
Connections	`M0` Free clusters can only have a maximum of 500 connections.
Cursors	Free clusters can't use the [noTimeout cursor option](https://www.mongodb.com/docs/manual/reference/method/cursor.addOption/#flags).
Custom Roles	Changes to [custom roles](https://mongodbcom-cdn.staging.corp.mongodb.com/docs/atlas/security-add-mongodb-roles/) might take up to 30 seconds to deploy in `M0` Free clusters.
Database and Collections	`M0` Free clusters can have a maximum of 100 databases and 500 collections total.
Database Commands	Certain database commands are unsupported or behave differently in an `M0` Free cluster. To learn more, see [Command Limits in Free Clusters](https://mongodbcom-cdn.staging.corp.mongodb.com/docs/atlas/unsupported-commands/#std-label-unsupported-commands). For questions or comments related to restricted commands, [contact support](https://mongodbcom-cdn.staging.corp.mongodb.com/docs/atlas/support/#std-label-request-support).
Access to Collections in `local`, `admin`, and `config` Databases	`M0` Free clusters don't allow: - Read access to any collection in the `local` database with the exception of read access to the oplog. You must precede a [`$regex`](https://www.mongodb.com/docs/manual/reference/operator/query/regex/#mongodb-query-op.-regex) query on an [oplog](https://www.mongodb.com/docs/manual/reference/glossary/#std-term-oplog) in an `M0` Free cluster or a Flex cluster with a carat (`^`). Otherwise, the following error occurs: ```sh MongoServerError: Oplog ns RegEx queries must begin with ^ ``` - Write access to any collection in the `local` and `config` databases. - Read or write access to any collection in the `admin` database. Atlas issues an error similar to the following if you attempt to read or write to collections in these databases: ```none command is not allowed in this Atlas tier (Unauthorized) not authorized on to execute command ``` </td> </tr>
Database Logs	`M0` Free clusters don't allow you to download logs.
Data Transfer Limits	`M0` Free clusters limit the total data transferred into or out of the cluster in a rolling seven-day period. The rate limits vary by cluster tier as follows: - `M0`: 10 GB in and 10 GB out per period Atlas handles clusters that exceed the rate limit as follows: - Atlas throttles the network speed of the cluster. - Atlas triggers a one second cooldown period before resuming the cluster's operations on a given connection. If the queue is greater than the operations per second limit, operations might wait for more than a second in the queue. - If the amount of transferred data drops below the rate limit threshold, Atlas resumes processing of the queued data transfers on each connection before processing any new data transfers on that connection.
Data Storage	`M0` Free clusters limit the maximum total data storage space as follows: - `M0`: 0.5 GB Data storage space includes the number of bytes of all uncompressed BSON documents stored in all collections, plus the bytes stored in their associated indexes.
JavaScript	`M0` Free clusters don't support server-side JavaScript. For example, [$where](https://www.mongodb.com/docs/manual/reference/operator/query/where/) and [map-reduce](https://www.mongodb.com/docs/manual/core/map-reduce/) are unsupported.
Namespaces and Database Names	`M0` Free cluster namespaces are limited to 95 bytes. Database names are limited to 38 bytes.
Number of Free Clusters	You can deploy at most *one* `M0` Free cluster per Atlas project. However if you have sales contracts with MongoDB, you might be able to deploy more `M0` clusters per project. To learn more, contact a MongoDB sales representative.
Performance Advisor	`M0` Free clusters don't provide access to the [Performance Advisor](https://mongodbcom-cdn.staging.corp.mongodb.com/docs/atlas/performance-advisor/).
Query Utilization	The percentage of time that a query is running over any five minute period must remain under 100% on `M0` Free clusters.
Real-Time Performance Panel	`M0` Free clusters don't provide access to the [Real-Time Performance Panel](https://mongodbcom-cdn.staging.corp.mongodb.com/docs/atlas/real-time-performance-panel/).
Sort in Memory	`M0` Free clusters sort in memory limit is 32 MB.
Throughput	`M0` Free clusters limit the number of read and write operations per second. The rate limits vary by cluster tier as follows: - `M0`: 100 operations per second Atlas handles clusters that exceed the operations per second rate limit as follows: - Atlas throttles the network speed of the cluster. - Atlas triggers a one second cooldown period before resuming the cluster's operations on a given connection. If the queue is greater than the operations per second limit, operations might wait for more than a second in the queue. - If the number of operations per second drops below the rate limit threshold, Atlas resumes processing of the queued operations on each connection before processing any new operations on that connection.
Automatic Pause of Idle Clusters	Atlas automatically pauses `M0` Free clusters after 60 days of inactivity where there are zero connections to the cluster. You can [resume](https://mongodbcom-cdn.staging.corp.mongodb.com/docs/atlas/pause-terminate-cluster/#std-label-resume-cluster) the cluster at any time *unless* the paused cluster was running on an old version that Atlas can't restore to the current version. You should export a copy of your data if you don't plan to use your Free cluster for an extended period of time. To learn more, see [Restore Data From Paused M0 Cluster](https://mongodbcom-cdn.staging.corp.mongodb.com/docs/atlas/backup/restore-free-tier-cluster/#std-label-restore-free-tier-cluster).

Driver

Description

Drivers that use a JRE (Java Runtime Environment) or JDK (Java Development Kit)'

Due to an issue with TLS (Transport Layer Security) 1.3 support in the Java JDK (Java Development Kit)' ([JDK-8236039](https://bugs.openjdk.java.net/browse/JDK-8236039)), upgrade the JDK (Java Development Kit)' that supports the driver you use to connect to Atlas. Minimum versions of the JDK (Java Development Kit)' include: 14u-cpu [JDK-8249107](https://bugs.openjdk.java.net/browse/JDK-8249107) 14.0.2 [JDK-8247954](https://bugs.openjdk.java.net/browse/JDK-8247954) 13.0.3 [JDK-8241515](https://bugs.openjdk.java.net/browse/JDK-8241515) 11.0.8-oracle [JDK-8238504](https://bugs.openjdk.java.net/browse/JDK-8238504) 11.0.7 [JDK-8237387](https://bugs.openjdk.java.net/browse/JDK-8237387) 8u261 [JDK-8243759](https://bugs.openjdk.java.net/browse/JDK-8243759) emb-8u261 [JDK-8247097](https://bugs.openjdk.java.net/browse/JDK-8247097) To learn more about support for TLS (Transport Layer Security) 1.3 in Java-based languages, libraries, and drivers, see: - [MongoDB Java, Reactive Streams, and Scala Drivers](https://mongodb.github.io/mongo-java-driver/) - [Scala](https://docs.scala-lang.org/overviews/jdk-compatibility/overview.html) - [Kafka](https://kafka.apache.org/documentation/#java)