Use Delta Lake's Time Travel to Access and Query Historical Data Versions. DATA-ANALYST-ASSOCIATE Practice Questions (Page 4)

Questions 16–20

1. 16application · medium

   A data analyst created a view `v_orders_2024` that filters the `orders` table for orders placed in 2024. The analyst needs to query this view as of version 12. Which statement is correct?

   • AThe analyst should recreate the view with a WHERE clause that filters by a version column.
   • BThe analyst must apply time travel to the underlying `orders` table, not the view.
   • CThe analyst can use `SELECT * FROM v_orders_2024 VERSION AS OF 12`.
   • DThe analyst can use `SELECT * FROM v_orders_2024 TIMESTAMP AS OF '2024-01-01'`.
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2. 17expert · hard

   A data analyst needs to query the `orders` table as it existed at 12:00 UTC on June 1, 2024. The analyst runs the query with `TIMESTAMP AS OF '2024-06-01T12:00:00.000+00:00'` but receives an error. The analyst checks `DESCRIBE HISTORY orders` and sees that the table was created on June 2, 2024. What is the most likely cause of the error?

   • AThe VACUUM command was run, removing the data files for that time.
   • BThe timestamp format is incorrect.
   • CThe analyst is using the wrong table name.
   • DThe timestamp is before the table was created, so there is no version available at that time.
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4. 18foundation · easy

   What is the effect of running VACUUM on a Delta table?

   • AIt restores the table to its previous version.
   • BIt cleans up the transaction log by removing old entries.
   • CIt removes data files that are no longer needed, potentially making older versions unavailable for time travel.
   • DIt compacts small files to improve query performance.
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5. 19application · medium

   A financial analyst needs to audit the `transactions` table as it appeared at 09:30 UTC on March 3, 2024. The analyst knows the table had several updates throughout the day but does not know the exact version numbers. Which query should the analyst run?

   • ASELECT * FROM transactions VERSION AS OF 5
   • BSELECT * FROM transactions TIMESTAMP AS OF '2024-03-03T09:30:00.000+00:00'
   • CSELECT * FROM transactions FOR TIMESTAMP AS OF '2024-03-03 09:30:00'
   • DSELECT * FROM transactions AS OF TIMESTAMP '2024-03-03T09:30:00'
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6. 20foundation · easy

   What is the primary purpose of Delta Lake time travel?

   • ATo permanently delete old data versions from storage to reduce costs.
   • BTo create a new table that contains only the most recent changes since the last commit.
   • CTo enable querying a table's historical data as it existed at a previous version or point in time.
   • DTo automatically synchronize a Delta table with an external database in real time.
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