Slow Extract Creation and Large Extract Size When Data Source Contains a Join

When creating or refreshing an extract of a data source that contains tables combined using a join, the process may take much longer than creating or refreshing an extract of the individual tables, and the extract may also be much larger than extracts of the individual tables, or the extract creation or refresh may not complete.

This can manifest in several different ways. Some symptoms you may encounter during extract creation:

1. The "Extracting Data" dialog is stuck on "Importing data".
2. An error indicates "There is not enough space on the disk".

Cause

The "Logical Tables" data storage option creates a denormalized extract. If this option is used with a data source containing a join, the join is applied when the extract is created, and this results in an extract containing more records.