Understand Delta Optimization Techniques, Such as Deletion Vectors and Liquid Clustering. DATA-ENGINEER-PROFESSIONAL Practice Questions (Page 4)

Questions 16–20

1. 16expert · hard

   A company has a Delta table that is used for both transactional updates and analytical queries. The table has frequent small deletes and updates, and queries often filter on a `category` column. The team wants to minimize storage cost and query latency. What is the best approach?

   • APartition the table by `category` and enable deletion vectors.
   • BUse liquid clustering only and perform full table rewrites for deletes.
   • CEnable deletion vectors only and rely on them for query performance.
   • DEnable deletion vectors and liquid clustering on `category`, and schedule periodic OPTIMIZE runs.
   Reveal Solution Discussion Select an answer first
2. 17expert · hard

   A company has a Delta table that is queried by different teams with different filter columns. The table is updated frequently, and the team wants to avoid manual maintenance. They are considering liquid clustering. What is a key consideration they should evaluate?

   • ALiquid clustering is only useful for tables with a single clustering key.
   • BLiquid clustering automatically optimizes for all possible query filters.
   • CLiquid clustering works best when the clustering keys align with the most common query filters, so they should analyze query patterns first.
   • DLiquid clustering eliminates the need for any file compaction.
   Reveal Solution Discussion Select an answer first
4. 18expert · hard

   A company has a large Delta table that is used for both real-time dashboards and nightly batch analytics. The table experiences frequent small deletes and updates, and queries often filter on a `region` column. The team wants to minimize query latency and storage costs. What should they do?

   • AUse liquid clustering only, and perform full table rewrites for deletes.
   • BPartition the table by `region` and enable deletion vectors.
   • CEnable deletion vectors for efficient deletes and liquid clustering on `region` for query performance.
   • DEnable deletion vectors only, and rely on them to improve query performance.
   Reveal Solution Discussion Select an answer first
5. 19expert · hard

   A data engineer is troubleshooting a Delta table with deletion vectors enabled. A `DELETE` operation removed 5% of the rows, but the table size did not decrease. What is the reason for this?

   • AThe table is not optimized, so the delete operation rewrote all files.
   • BDeletion vectors mark rows as deleted without rewriting the data files, so the physical files remain unchanged.
   • CThe delete operation created new files and left the old files in place.
   • DThe delete operation failed and did not actually remove any rows.
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6. 20foundation · easy

   Which Delta Lake operation is most directly optimized by the use of deletion vectors?

   • AMERGE operations that update all rows in a table
   • BSELECT queries that read the entire table
   • CDELETE operations that remove a small subset of rows
   • DINSERT operations that add new rows
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