Question 42

You are tuning a large, fast-growing Unity Catalog Delta table. Queries frequently filter on a **high-cardinality** `customer_id` column, the query patterns change over time, and the table receives **frequent small `MERGE`/`UPDATE`/`DELETE`** operations from an upsert pipeline. You want to avoid the small-file problems of partitioning, avoid having to re-specify columns on every `OPTIMIZE`, and accelerate row-level modifications. Which **two** actions best meet these goals? (Choose TWO.)

• AEnable **liquid clustering** with `CLUSTER BY (customer_id)`, which supports high-cardinality keys and lets you redefine clustering keys later without rewriting existing data.
• BEnable **deletion vectors** (`delta.enableDeletionVectors = true`) so `MERGE`, `UPDATE`, and `DELETE` mark rows as removed without rewriting whole Parquet files.
• CUse **Z-ordering** (`OPTIMIZE ... ZORDER BY (customer_id)`) and combine it on the same table with liquid clustering for additive benefits.
• DUse **Hive-style partitioning** on `customer_id` to physically isolate each customer's data.
• EDisable deletion vectors and rely on full-file rewrites to keep older non-DV readers compatible.