What is TDE file?

TDE stands for Tableau Data Extract — the old file format for extracted data, a columnar store designed for analytic queries rather than transactional ones.

Columnar storage is why extracts are fast: a query reads only the columns it needs, the data compresses well, and the engine is built around keeping hot data in memory.

Since version 10.5 the format is .hyper, backed by the Hyper engine, which is faster and handles larger extracts. Existing .tde files are upgraded when a workbook is opened and refreshed.

You will still see .tde in older documentation and in interview questions written a few years ago, so it is worth knowing both names and which superseded which.