Develop data processing →hardMultiple ChoiceObjective-mapped

DP-203 Develop data processing Practice Question

Exhibit

Refer to the exhibit.

{
  "type": "MappingDataFlow",
  "typeProperties": {
    "sources": [
      {
        "dataset": {
          "referenceName": "DelimitedTextSource",
          "type": "DatasetReference"
        },
        "script": "source(\n  output() as (\n    col1 string,\n    col2 string\n  ),\n  allowSchemaDrift: true,\n  validateSchema: false\n) ~> Source1"
      }
    ],
    "sinks": [
      {
        "dataset": {
          "referenceName": "AzureSynapseTableSink",
          "type": "DatasetReference"
        },
        "script": "Source1 sink(\n  input() as (\n    col1 string,\n    col2 string\n  ),\n  allowSchemaDrift: true,\n  validateSchema: false\n) ~> Sink1"
      }
    ]
  }
}

You are reviewing a Mapping Data Flow in Azure Data Factory that copies data from a CSV file to an Azure Synapse table. The data flow uses 'allowSchemaDrift: true' and 'validateSchema: false'. After running the pipeline, you notice that the target table does not have the expected columns. The CSV file sometimes has extra columns. What is the most likely reason?

⚠ Common exam trap

Many candidates assume enabling 'allowSchemaDrift' on the source automatically writes all columns to the sink, but they overlook that explicit sink mappings override auto-mapping and exclude drifted columns.

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

The sink mapping is explicitly defined and does not include auto-mapping for drifted columns.

When 'allowSchemaDrift' is enabled on the source, drifted columns are detected but will only be written to the sink if auto-mapping is used. If the sink mapping is explicitly defined (e.g., column-by-column mappings), it overrides auto-mapping and drifted columns are ignored. Since the target table is missing expected columns, the explicit mapping likely excludes the drifted columns.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
Schema drift is not enabled on the source.
Why it's wrong here
The source has allowSchemaDrift: true.
✓
The sink mapping is explicitly defined and does not include auto-mapping for drifted columns.
Why this is correct
The sink script defines input columns, so extra columns are not mapped.
✗
The sink dataset has a fixed schema that does not allow drift.
Why it's wrong here
The sink has allowSchemaDrift: true.
✗
The source dataset has a fixed schema that does not include extra columns.
Why it's wrong here
The source dataset is DelimitedText without schema.

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DP-203 Develop data processing Practice Question

Exhibit

Why each option matters

Option-by-option breakdown

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