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DP-700 · Question #35

You have a Fabric workspace that contains a lakehouse named Lakehouse1. Lakehouse1 contains a Delta table named Table1. You analyze Table1 and discover that Table1 contains 2,000 Parquet files of 1…

The correct answer is C. Run the OPTIMIZE and VACUUM commands. To minimize query time on a Delta table with many small Parquet files, you should consolidate them into larger files and then remove the obsolete ones.

Monitor and optimize an analytics solution

Question

You have a Fabric workspace that contains a lakehouse named Lakehouse1. Lakehouse1 contains a Delta table named Table1. You analyze Table1 and discover that Table1 contains 2,000 Parquet files of 1 MB each. You need to minimize how long it takes to query Table1. What should you do?

Options

  • ADisable V-Order and run the OPTIMIZE command.
  • BDisable V-Order and run the VACUUM command.
  • CRun the OPTIMIZE and VACUUM commands.
  • DEnable V-Order and run the OPTIMIZE command.

How the community answered

(30 responses)
  • A
    7% (2)
  • B
    3% (1)
  • C
    80% (24)
  • D
    10% (3)

Why each option

To minimize query time on a Delta table with many small Parquet files, you should consolidate them into larger files and then remove the obsolete ones.

ADisable V-Order and run the OPTIMIZE command.

Disabling V-Order is generally not recommended for performance, and while OPTIMIZE helps, VACUUM is also needed for cleanup.

BDisable V-Order and run the VACUUM command.

Disabling V-Order is generally not recommended, and VACUUM alone does not consolidate small files; it only removes unreferenced ones.

CRun the OPTIMIZE and VACUUM commands.Correct

Running the OPTIMIZE command on the Delta table will consolidate the 2,000 small 1 MB Parquet files into fewer, larger files, significantly reducing metadata overhead and improving scan performance. Subsequently, running the VACUUM command will remove the old, unreferenced 1 MB files, freeing up storage and further optimizing the table for quicker queries.

DEnable V-Order and run the OPTIMIZE command.

While OPTIMIZE is correct, V-Order should generally be enabled for performance, not disabled, and VACUUM is still necessary to clean up old files.

Concept tested: Delta Lake table optimization (OPTIMIZE, VACUUM)

Source: https://learn.microsoft.com/en-us/fabric/data-warehouse/delta-lake-overview#delta-table-maintenance

Topics

#Delta Lake Optimization#File Compaction#Query Performance Tuning#Fabric Lakehouse

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