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 when the data point was recorded.
- Metadata (sometimes referred to as source), which is a label or tag that uniquely identifies a series and rarely changes.
- Measurements (sometimes referred to as metrics or values), which are the data points tracked at increments in time. Generally these are key-value pairs that change over time.
This table shows examples of time series data:
Stock ticker, exchange
Sensor identifier, location
For efficient time series data storage, MongoDB provides 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.
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.
Time series collections use an underlying columnar storage format and store data in time-order with an automatically created clustered index. The columnar storage 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
Time series collections behave like normal collections. You can insert and query your data as you normally would.
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.
When you query time series collections, you operate on one document per measurement. Queries on time series collections take advantage of the optimized internal storage format and return results faster.
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.
When you create a time series collection, MongoDB automatically creates an internal clustered index on the time field. The internal index provides several performance benefits including improved query efficiency and reduced disk usage. To learn more about the performance benefits of clustered indexes, see Clustered Collections.
The internal index for a time series collection is not displayed by
To improve query performance, you can manually add secondary indexes on measurement fields or any field in your time series collection.
To get started with time series collections, see Create and Query a Time Series Collection.