Time Series

Time series data is a sequence of data points in which insights are gained by analyzing changes over time.

Time series data is generally composed of these components:

Time: Indicates when the data point was recorded.
Metadata: A label or tag that identifies a data series and rarely changes. Metadata is stored in a metaField. You cannot add a metaField field to a time series document after you create it. Metadata is also known as source. For more information, see metaFields.
Metrics: Individual data points tracked at increments in time, often displayed as key-value pairs that change over time. Metrics are also known as values.
Measurements: Documents that contain data for all metrics at a specific point in time. A measurement includes the time, metadata, and all metrics recorded at that moment.

This table shows examples of time series data:

Example	Metrics	Metadata
Stock data	Stock price	Stock ticker, exchange
Weather data	Temperature	Sensor identifier, location
Website visitors	View count	URL

For efficient time series data storage, MongoDB provides time series collections.

The following example shows a measurement document for weather data:

{
  "timestamp": ISODate("2025-08-19T12:00:00Z"),
  "metaField": {
    "sensorId": "A1234",
    "location": {
      "city": "New York",
      "state": "NY"
    }
  },
  "temperature": 25.4,
  "humidity": 48.2,
  "pressure": 1012.5,
  "windSpeed": 5.2,
  "windDirection": "NW"
}

In this example, the measurement contains:

A timestamp showing when the data was recorded.
Metadata identifying the sensor and its location.
Multiple metrics, including temperature, humidity, pressure, wind speed, and direction, collected at the given time.

Time Series Collections

New in version 5.0.

Time series collections efficiently store time series data. In time series collections, writes are organized so that data from the same source is stored alongside other data points from a similar point in time.

You can create time series collections in the UI for deployments hosted in MongoDB Atlas.

Important

Backwards-Incompatible Feature

You must drop time series collections before downgrading:

MongoDB 6.0 or later to MongoDB 5.0.7 or earlier.
MongoDB 5.3 to MongoDB 5.0.5 or earlier.

Benefits

Compared to normal collections, storing time series data in time series collections improves query efficiency and reduces the disk usage for time series data and secondary indexes. MongoDB 6.3 and later automatically creates a compound index on the time and metadata fields for new time series collections.

Time series collections use an underlying columnar storage format and store data in time-order. This format provides the following benefits:

Reduced complexity for working with time series data
Improved query efficiency
Reduced disk usage
Reduced I/O for read operations
Increased WiredTiger cache usage

Example Use Cases

Time Series collections are optimal for analyzing data over time. The following table illustrates use cases for time series data:

Industry	Examples
Internet of Things (IoT)	Sensor data (for example, smart home devices or fleet logistics) Machine learning and artificial intelligence scraping
Financial Services	High frequency trading Financial quantitative analysis Banking data (for example, accounting of banking transactions over time) Stock market data
Retail and E-Commerce	Transaction, sales, and price analysis Inventory management
DevOps	Application logging Infrastructure and network monitoring

Time Series collections are not intended for the following types of data:

Unordered data
Data that is not time-dependent

Behavior

Time series collections generally behave like other MongoDB collections. You insert and query data as usual.

Warning

Match expressions in update commands can only specify the metaField. You can't update other fields in a time series document. For more details, see Time Series Update Limitations.

MongoDB treats time series collections as writable non-materialized views backed by an internal collection. When you insert data, the internal collection automatically organizes time series data into an optimized storage format.

Starting in MongoDB 6.3: if you create a new time series collection, MongoDB also generates a compound index on the metaField and timeField fields. To improve query performance, queries on time series collections use the new compound index. The compound index also uses the optimized storage format.

Warning

Starting in MongoDB 8.0, use of the timeField as a shard key in a time series collection is deprecated.

Also, starting in MongoDB 8.0, if you create a time series collection with a shard key containing the timeField, a log message is added to the log file on the primary shard. In addition, a log message is added every 12 hours on the primary node of the config server replica set. The log messages state that using the timeField as a shard key in a time series collection is deprecated and you must reshard your collection using the metaField.

metaFields

Time series documents can contain a metaField with metadata about each document. MongoDB uses the metaField to group sets of documents, both for internal storage optimization and query efficiency. For more information about the metaField, see metaField Considerations.

Indexes

MongoDB automatically creates a compound index on both the metaField and timeField of a time series collection.

Zone Sharding

Zone sharding does not support time series collections. The balancer always distributes data in sharded time series collections evenly across all shards in the cluster.

Next Steps

To get started with time series collections, see the tutorials on the following pages:

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