How does QlikView treat joins when no prefix is specified?

In QlikView, when no prefix is specified, the default behavior is to perform an outer join. This means that when two tables are joined without explicit instructions on the type of join to apply, QlikView will include all records from both tables and match them where possible. If there are records in either table that do not have a corresponding match in the other table, those records will still be present in the result set with null values for fields from the table that lacks a corresponding record.

This default outer join behavior allows users to retain all possible data during the merging of datasets, which can be particularly useful for analysis that requires complete data visibility, ensuring no information is lost simply due to a lack of matching keys between datasets.

The other types of joins, such as inner and cross joins, would limit the resulting dataset in various ways, focusing on matched records or creating cartesian products respectively, which are not the defaults in QlikView without specified prefixes.