server-side error: There is already an object named DataExtract...

[wjchulme]

I ran a cohort extraction action on the server, but it returned an error. I checked the error log and it said _tds.ProgrammingError: There is already an object named 'DataExtract_<hash>' in the database (hash is the unique id of the data extract).

I re-ran the action and it worked.

[wjchulme]

This can happen when two identical data extracts are running at the same time. This happens when two identical data extraction queries are running at the same time, for instance because:

• Two different cohortextractor generate_cohort actions are actually pointing to the same study definition
• Two people are running the same action at the same time in different workspaces
• Two study definitions have different dummy data speifications but are identical with respect to the data extraction query

[wjchulme]

An issue for handling this more gracefully is here: opensafely-core/cohort-extractor#447