DP-300 Practice Question: Monitor, configure, and optimize database resources
You are optimizing an Azure SQL Database that has a large table with a clustered columnstore index. You notice that the index has been fragmented over time. You need to improve query performance. What should you do?
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
✓
Reorganize the columnstore index
REORGANIZE is the recommended maintenance operation for clustered columnstore indexes to defragment them by removing rows from deleted bitmaps without requiring a full rebuild. Option A (drop and recreate) is incorrect because it is disruptive and unnecessary for resolving fragmentation. Option C (update statistics) does not address index fragmentation directly. Option D (rebuild) is more resource-intensive and typically reserved for indexes with high fragmentation, whereas reorganize is optimal for regular maintenance.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Drop and recreate the columnstore index
Why it's wrong here
Dropping and recreating is disruptive and not recommended.
- ✓
Reorganize the columnstore index
Why this is correct
REORGANIZE removes rows from deleted bitmaps and is the recommended maintenance.
- ✗
Update statistics on the table
Why it's wrong here
Updating statistics helps query optimization but does not address fragmentation.
- ✗
Rebuild the columnstore index
Why it's wrong here
Rebuild is resource-intensive and may cause downtime.
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Related to this question
Learn chapter
Overview of Azure Data Platform Options
Key term
Azure SQL Indexes
Structures in Azure SQL Database that speed up data retrieval by providing quick access paths to rows, similar to a book index.
Key term
Azure SQL Performance Tuning
Azure SQL Performance Tuning is the process of optimizing the speed and efficiency of queries and database operations in Microsoft Azure SQL Database or SQL Managed Instance to reduce latency and improve throughput.
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