Which of the following functions is NOT available in USQL for user session data?

In USQL, which is used for querying user session data, the function that is not available is the AVERAGE function. This is significant because USQL is specifically designed to analyze user behavior and session data where typical aggregation functions like DISTINCT, TOP, and SUM are commonly used to summarize and manage data.

DISTINCT is used in USQL to ensure unique values are returned from a set of data, while TOP allows for retrieving a specified number of rows from the result set, which is essential for performance tuning and reporting. Similarly, SUM is a basic aggregate function that enables users to calculate total values across a dataset, making it particularly useful for analyzing metrics such as total engagement or page views.

The absence of an AVERAGE function highlights a limitation in USQL when it comes to calculating mean values, which would typically help in assessing the central tendency of data. Instead, to derive average-like insights, users may need to use a combination of SUM and COUNT functions to compute averages manually or utilize other data processing methods. Understanding these functions' roles is crucial for effectively leveraging USQL in analyzing user session data.