---
title: Time series aggregation
description: The time series aggregation queries data created using a Time series data stream (TSDS). This is typically data such as metrics or other data streams...
url: https://docs-v3-preview.elastic.dev/elastic/elasticsearch/pull/139618/reference/aggregations/search-aggregations-bucket-time-series-aggregation
---

# Time series aggregation
<warning>
  This functionality is in technical preview and may be changed or removed in a future release. Elastic will work to fix any issues, but features in technical preview are not subject to the support SLA of official GA features.
</warning>

The time series aggregation queries data created using a [Time series data stream (TSDS)](https://docs-v3-preview.elastic.dev/elastic/docs-content/tree/main/manage-data/data-store/data-streams/time-series-data-stream-tsds). This is typically data such as metrics or other data streams with a time component, and requires creating an index using the time series mode.
<note>
  Refer to the [TSDS documentation](https://docs-v3-preview.elastic.dev/elastic/docs-content/tree/main/manage-data/data-store/data-streams/time-series-data-stream-tsds#differences-from-regular-data-stream) to learn more about the key differences from regular data streams.
</note>

Data can be added to the time series index like other indices:
```js
PUT /my-time-series-index-0/_bulk
{ "index": {} }
{ "key": "a", "val": 1, "@timestamp": "2022-01-01T00:00:10Z" }
{ "index": {}}
{ "key": "a", "val": 2, "@timestamp": "2022-01-02T00:00:00Z" }
{ "index": {} }
{ "key": "b", "val": 2, "@timestamp": "2022-01-01T00:00:10Z" }
{ "index": {}}
{ "key": "b", "val": 3, "@timestamp": "2022-01-02T00:00:00Z" }
```

To perform a time series aggregation, specify "time_series" as the aggregation type. When the boolean "keyed" is true, each bucket is given a unique key.

```js
GET /_search
{
  "aggs": {
    "ts": {
      "time_series": { "keyed": false }
    }
  }
}
```

This will return all results in the time series, however a more typical query will use sub aggregations to reduce the date returned to something more relevant.

## Size

By default, `time series` aggregations return 10000 results. The "size" parameter can be used to limit the results further. Alternatively, using sub aggregations can limit the amount of values returned as a time series aggregation.

## Keyed

The `keyed` parameter determines if buckets are returned as a map with unique keys per bucket. By default with `keyed` set to false, buckets are returned as an array.

## Limitations

The `time_series` aggregation has many limitations. Many aggregation performance optimizations are disabled when using the `time_series` aggregation. For example the filter by filter optimization or collect mode breath first (`terms` and `multi_terms` aggregation forcefully use the depth first collect mode).
The following aggregations also fail to work if used in combination with the `time_series` aggregation: `auto_date_histogram`, `variable_width_histogram`, `rare_terms`, `global`, `composite`, `sampler`, `random_sampler` and `diversified_sampler`.