DP-750 Certification Practice Question #46

Question

You are designing several one-time and recurring load operations into Unity Catalog. For each requirement, you must select the single most appropriate command from a dropdown. The available options for every row are: **COPY INTO**, **CREATE TABLE AS SELECT (CTAS)**, and **CREATE OR REPLACE TABLE (CRAS)**. ```mermaid flowchart TD subgraph HOTSPOT["Select the command for each requirement"] R1["Row 1: Incrementally and idempotently load thousands of new
JSON files that arrive over time into an existing Delta table;
already-loaded files must be skipped on re-runs"] -->|dropdown| D1["[ COPY INTO | CTAS | CRAS ]"] R2["Row 2: Create a brand-new managed Delta table in one statement
by querying an existing Hive metastore table (full migration,
no incremental reload needed)"] -->|dropdown| D2["[ COPY INTO | CTAS | CRAS ]"] R3["Row 3: Fully overwrite an existing reporting table's schema
and data each night from a SELECT, atomically replacing it
while keeping the same table name and history"] -->|dropdown| D3["[ COPY INTO | CTAS | CRAS ]"] end ```

Accepted Answer

COPY INTO is purpose-built for incremental, idempotent, retriable file ingestion into an *existing* Delta table — it tracks which files were already loaded and skips them, giving exactly-once semantics. CTAS creates a *new* table in a single statement from a query, the canonical pattern for a one-time migration. CREATE OR REPLACE TABLE atomically rewrites a table that already exists (schema and data) while keeping its identity, which fits a nightly full-overwrite reporting refresh. Each row maps to exactly one command.

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