Data Engineering Associate with Databricks Practice Exam

What does the complete output mode do in SQL streaming?

1. It appends data to existing results

2. It overwrites the table with complete results each time

3. It processes data without any output

4. It outputs summary statistics only

The correct answer is: It overwrites the table with complete results each time

The complete output mode in SQL streaming is designed to provide a complete view of the aggregated results every time there is a change in the data. This means that each time new data is processed, the entire result set is recalculated and written out, replacing any previous results. This is especially useful when the requirements call for a complete window of results, as opposed to just the latest updates. In this context, the complete mode ensures that the full summary is consistently up to date in the output, reflecting all the data that has been ingested up to that point. This differs from other modes, such as append mode, which would only add new records to the result without altering existing data. Additionally, some modes might skip outputs altogether, or only provide summary statistics, which would not fulfill the complete output capability of delivering comprehensive results.