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Time Series

Shard a Time Series Collection

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  • Limitations
  • Prerequisites
  • Procedures
  • Additional Information

New in version 5.1.

Use this tutorial to shard a new or existing time series collection.

Important

Before completing this tutorial, review the sharding limitations for time series collections.

Limitations

You can't reshard a sharded time series collection. However, you can refine its shard key.

Prerequisites

To shard a time series collection, you must deploy a sharded cluster to host the database that contains your time series collection.

Procedures

Shard a New Time Series Collection

1

Connect to your sharded cluster.

Connect mongosh to the mongos for your sharded cluster. Specify the host and port on which the mongos is running:

mongosh --host <hostname> --port <port>
2

Confirm that sharding is enabled on your database.

Run sh.status() to confirm that sharding is enabled on your database:

sh.status()

The command returns the sharding information:

--- Sharding Status ---
   sharding version: {
      "_id" : 1,
      "minCompatibleVersion" : 5,
      "currentVersion" : 6,
...
3

Create the collection.

Use the shardCollection() method with the timeseries option.

For example:

sh.shardCollection(
   "test.weather",
   { "metadata.sensorId": 1 },
   {
      timeseries: {
         timeField: "timestamp",
         metaField: "metadata",
         granularity: "hours"
      }
   }
)

In this example, sh.shardCollection():

  • Shards a new time series collection named weather on the test database.

  • Specifies the metadata.sensorId field as the shard key.

  • Specifies a granularity of hours.

The following document contains the appropriate metadata for the collection:

db.weather.insertOne( {
   "metadata": { "sensorId": 5578, "type": "temperature" },
   "timestamp": ISODate("2021-05-18T00:00:00.000Z"),
   "temp": 12
} )

Shard an Existing Time Series Collection

1

Connect to your sharded cluster.

Connect mongosh to the mongos for your sharded cluster. Specify the host and port on which the mongos is running:

mongosh --host <hostname> --port <port>
2

Confirm that sharding is enabled on your database.

Run sh.status() to confirm that sharding is enabled on your database:

sh.status()

The command returns the sharding information:

--- Sharding Status ---
   sharding version: {
      "_id" : 1,
      "minCompatibleVersion" : 5,
      "currentVersion" : 6,
...
3

Shard the collection.

Use the shardCollection() method to shard the collection.

Consider a time series collection with the following properties:

db.createCollection(
   "deliverySensor",
   {
      timeseries: {
         timeField: "timestamp",
         metaField: "metadata",
         granularity: "minutes"
      }
   }
)

A sample document from the collection resembles:

db.deliverySensor.insertOne( {
   "metadata": { "location": "USA", "vehicle": "truck" },
   "timestamp": ISODate("2021-08-21T00:00:10.000Z"),
   "speed": 50
} )

To shard the collection, run the following command:

sh.shardCollection( "test.deliverySensor", { "metadata.location": 1 } )

In this example, sh.shardCollection():

  • Shards an existing time series collection named deliverySensor on the test database.

  • Specifies the metadata.location field as the shard key. location is a sub-field of the collection's metaField.

When the collection you specify to sh.shardCollection() is a time series collection, you do not need to specify the timeseries option.

Additional Information

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