What join type should you use to include all rows from the primary pipeline, even without a match in the imported pipeline?

The left outer join is the appropriate choice to include all rows from the primary pipeline while allowing for matches to be made with the imported pipeline. This type of join returns all records from the left table (the primary pipeline) and the matched records from the right table (the imported pipeline). If there is no match found in the imported pipeline, the result will still include the row from the primary pipeline, with NULL values for the columns from the imported pipeline. This ensures that you maintain all the information from your primary source, even when there are discrepancies or lack of matches in the imported data.

In contrast, the inner join only returns rows when there is a match in both tables, excluding any rows from the primary pipeline that do not have corresponding matches in the imported pipeline. The right outer join would include all rows from the imported pipeline, which is not suitable since the primary pipeline is the focus. Lastly, the full outer join would return all rows from both pipelines regardless of whether they match, which provides more data than required in this case where the priority is to keep all entries from the primary pipeline.