Apply Liquid Clustering to Improve Query Speed When Filtering Large Tables on Specific Columns. DATA-ANALYST-ASSOCIATE Practice Questions (Page 4)

Questions 16–20

1. 16expert · hard

   A team has a Delta table clustered on `country` and `device_type`. A query filters on `device_type = 'mobile'` and `country = 'US'`. How does Liquid Clustering help this query?

   • AIt compresses the data files to reduce I/O.
   • BIt caches the query results so subsequent runs are faster.
   • CIt allows the query engine to skip files that do not contain US mobile data, reducing the amount of data scanned.
   • DIt creates an index on `country` and `device_type` for faster lookups.
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2. 17expert · hard

   A company has a large Delta table with columns `tenant_id` (about 1,000 distinct values), `event_date` (high cardinality), and `event_type` (about 50 distinct values). Analysts run two types of queries: (1) filters on `tenant_id` and `event_date` to get daily summaries, and (2) filters on `event_type` to get cross-tenant aggregations. The team wants to enable Liquid Clustering. Which clustering columns should they choose to balance performance for both query patterns?

   • A`event_type` only
   • B`tenant_id` and `event_date`
   • C`tenant_id` only
   • D`tenant_id`, `event_date`, and `event_type`
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4. 18application · medium

   A retail analytics team has a Delta table of 2 billion sales transactions. Analysts frequently run queries filtering on `order_date` (a high-cardinality date column) and `store_id` (a low-cardinality column with about 500 distinct values). The team wants to enable Liquid Clustering to reduce the amount of data scanned. Which column configuration should they choose?

   • ACluster on `order_date` only, because high-cardinality columns are the only valid clustering keys.
   • BCluster on both `order_date` and `store_id`.
   • CCluster on `store_id` only, because low-cardinality columns are always the best clustering keys.
   • DDo not enable Liquid Clustering; instead, create a separate table for each store.
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5. 19expert · hard

   A team has a Delta table that is currently not clustered. They want to enable Liquid Clustering on `department` and `employee_id`. They run `ALTER TABLE employees CLUSTER BY (department, employee_id);` and then immediately run a query that filters on `department = 'Engineering'`. What is the expected behavior?

   • AThe query will scan the entire table because clustering is not effective until the table is recreated.
   • BThe query will run, but it may not see the full performance benefit until `OPTIMIZE` is run to physically reorganize the data.
   • CThe query will fail because the table is not yet optimized.
   • DThe query will be immediately faster because the data is reorganized on the fly.
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6. 20foundation · easy

   Which SQL clause is used to enable Liquid Clustering when creating a new Delta table?

   • ASORT BY
   • BPARTITIONED BY
   • CCLUSTER BY
   • DORDER BY
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