Question

A data engineer runs OPTIMIZE on a Delta table daily to improve query performance. A colleague asks to be able to query the table as it existed 10 days ago using time travel. However, the engineer recently ran VACUUM my_table RETAIN 48 HOURS on the table. What is the outcome when the colleague attempts the 10-day-old time travel query?

Accepted Answer

The query fails because VACUUM removed the underlying data files older than 48 hours that the older version referenced.

Answer

The query succeeds because Delta always retains 30 days of history regardless of VACUUM settings.

Answer

The query succeeds because OPTIMIZE preserves all historical versions in the transaction log permanently.

Answer

The query fails because time travel is disabled once VACUUM is run on a table.