So far, you have seen how to bucket (or segment, or slice) your data on different types of columns/fields. The analysis of data across the time dimension is another very common requirement. We may have questions such as the following, which require the aggregation of data on the time dimension:

• How are sales volumes growing over a period of time?
• How is profit changing from month to month?

In the context of the network traffic example that we are going through, the following questions can be answered through time series analysis of the data:

• How are the bandwidth requirements changing for my organization over a period of time?
• Which are the top applications, over a period of time, in terms of bandwidth usage?

Elasticsearch has a very powerful Date Histogram aggregation that can answer questions like these. Let's look at how we can get answers to these questions.