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Development Checklist

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  • Data Durability
  • Schema Design
  • Replication
  • Sharding
  • Drivers

The following checklist, along with the Operations Checklist, provides recommendations to help you avoid issues in your production MongoDB deployment.

  • Ensure that your replica set includes at least three data-bearing nodes with w:majority write concern. Three data-bearing nodes are required for replica-set wide data durability.
  • Ensure that all instances use journaling.

Data in MongoDB has a dynamic schema. Collections do not enforce document structure. This facilitates iterative development and polymorphism. Nevertheless, collections often hold documents with highly homogeneous structures. See Data Modeling Concepts for more information.

  • Determine the set of collections that you will need and the indexes required to support your queries. With the exception of the _id index, you must create all indexes explicitly: MongoDB does not automatically create any indexes other than _id.
  • Ensure that your schema design supports your deployment type: if you are planning to use sharded clusters for horizontal scaling, design your schema to include a strong shard key. While you can change your shard key later, it is important to carefully consider your shard key choice to avoid scalability and perfomance issues.
  • Ensure that your schema design does not rely on indexed arrays that grow in length without bound. Typically, best performance can be achieved when such indexed arrays have fewer than 1000 elements.
  • Consider the document size limits when designing your schema. The BSON Document Size limit is 16MB per document. If you require larger documents, use GridFS.
  • Use an odd number of voting members to ensure that elections proceed successfully. You can have up to 7 voting members. If you have an even number of voting members, and constraints, such as cost, prohibit adding another secondary to be a voting member, you can add an arbiter to ensure an odd number of votes. For additional considerations when using an arbiter for a 3-member replica set (P-S-A), see Replica Set Arbiter.

    Note

    For the following MongoDB versions, pv1 increases the likelihood of w:1 rollbacks compared to pv0 (no longer supported in MongoDB 4.0+) for replica sets with arbiters:

    • MongoDB 3.4.1
    • MongoDB 3.4.0
    • MongoDB 3.2.11 or earlier

    See Replica Set Protocol Version.

  • Ensure that your secondaries remain up-to-date by using monitoring tools and by specifying appropriate write concern.
  • Do not use secondary reads to scale overall read throughput. See: Can I use more replica nodes to scale for an overview of read scaling. For information about secondary reads, see: Read Preference.

  • Make use of connection pooling. Most MongoDB drivers support connection pooling. Adjust the connection pool size to suit your use case, beginning at 110-115% of the typical number of concurrent database requests.
  • Ensure that your applications handle transient write and read errors during replica set elections.
  • Ensure that your applications handle failed requests and retry them if applicable. Drivers do not automatically retry failed requests.
  • Use exponential backoff logic for database request retries.
  • Use cursor.maxTimeMS() for reads and wtimeout for writes if you need to cap execution time for database operations.
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On this page

  • Data Durability
  • Schema Design
  • Replication
  • Sharding
  • Drivers