How to copy Tableau Data Extract logic?

Question

Someone in my org created a Data Extract. There is an issue in one of the worksheets that uses it, and we suspect it's due to a mistake in how the Union was built.

But since it's a Data Extract, I can't see the UI for the data merge. Is there anyway to take a current Data Extract and view the logic that creates it?

Answer 1

Before going too deep into extract details, note that extracts are not intended to be permanent systems of record for data - just an efficient way to work with query results for optimized reporting. So in general, you should always be able to throw away the extract and look at the original source - or recreate the extract on command. But life isn't always perfect so ...

If you use Tableau Desktop to look at your worksheet, and look at the data source icon at the top of the data pane in the left sidebar, do you see an icon for your data source that looks like two databases with one on top of (shadowing) the other? If so, you can at right click on the data source icon and view its properties to see the source database table or file path. You can then even try disabling the extract to view the original source data.

If instead you see a single database icon, you have a "naked" extract where you've discarded the reference to the original source, (unless it is stored in the catalog mentioned below.)

If your organization purchased the Data Management Add-on for Tableau Server (strongly recommended), then if your data source is published to Tableau Server you can trace its history and origin by exploring the Tableau Catalog. That is especially valuable if the extract was built by a Tableau Prep Flow.

If instead, someone built the extract another way, say by writing a custom app using the Tableau Data Extract API, then the answer is to find that program.

One last point, in recent versions of Tableau, extracts are stored in an efficient relational type database file called Hyper. Hyper extracts can either be a single table (say serializing the results of a query joining multiple tables) or a Hyper extract can contain multiple tables (say serializing caching individual tables and deferring the join for later).

That may not be relevant to your question, but could turn out to matter as you reverse engineer how the extract was created.

Answer 2

Download the extract from the server (I'm assuming you're using server), then open that extract using desktop. You should be able to see the details of it.