Tableau Prep essentials

What does the profile pane show?

A distribution of values for every field, including null counts — data quality visible without writing a query.

While building, what data does Prep use?

A sample, so rare values may not appear until you run the flow on the full data.

What makes the Prep join step better than a SQL inner join for data prep?

It shows matched and unmatched counts, and clicking the unmatched section reveals exactly which values failed.

A join produces more rows than the left input. Cause and fix?

Duplicate keys on the right caused a fan-out. Add an aggregate step on that branch, grouped by the join key.

Which grouping method merges "Houston, TX" with "TX Houston"?

Common Characters — it ignores order and punctuation.

What is the risk of automatic value grouping?

It merges values that are genuinely different, and the mistake disappears silently into one row.

Why split names from the right?

The last token is reliably the surname, so an optional middle name does not shift the columns.

Which Tableau feature is NOT supported in Prep?

Table calculations — they need view context, so they belong in Desktop.

What does a wildcard pivot do?

Pivots any column matching a pattern, including columns that do not exist yet, so the flow survives new months.

Aggregate step versus FIXED LOD?

The aggregate step changes the grain; a FIXED LOD keeps every row and attaches the group value to each.

Why rename Pivot1 Names and Pivot1 Values immediately?

The defaults are meaningless a few steps later and end up in the output.

Your output table doubled on the second run. Why?

The write option was set to Append rather than create/replace.

Which output gives a team one shared refreshed source?

A published data source on Server or Cloud.

What is needed to schedule flows on Server?

Tableau Prep Conductor, or driving the command line from an external scheduler.

Where is the cheapest place to filter rows?

The input step — excluded rows never enter the flow.