The correct action is to re-create the partition function with a different boundary type, such as RIGHT instead of LEFT, to align with query patterns. When partition elimination is not working in Azure SQL Database, the most common cause is a mismatch between the partition function’s boundary alignment and the query’s predicate on the partitioning column. A LEFT-based partition function stores each boundary value in the left partition, which can cause queries filtering on a range like “OrderDate >= ‘2024-01-01’” to scan all partitions if the boundary values don’t cleanly separate the data into the queried months. On the DP-300 exam, this scenario tests your understanding of partition design and predicate sargability—a common trap is assuming statistics or indexes alone fix elimination. Remember the memory tip: “LEFT lags, RIGHT aligns”—LEFT boundaries include the boundary value in the prior partition, often breaking range scans, while RIGHT boundaries place it in the current partition, enabling precise partition pruning for monthly aggregates.
DP-300 Practice Question: Monitor, configure, and optimize database resources
This DP-300 practice question tests your understanding of monitor, configure, and optimize database resources. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
You are the database administrator for a large e-commerce application hosted on Azure SQL Database in the Business Critical tier (8 vCores). The database has a table named Orders with 500 million rows. The table is partitioned by OrderDate using a monthly partition function. The application frequently runs queries that aggregate sales by month for the current year. Users report that these queries are slow. You examine the query execution plans and notice that the queries are scanning all partitions, not just the relevant ones. You need to improve query performance without changing the application code. Which action should you take?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Re-create the partition function with a different boundary type (e.g., RIGHT instead of LEFT) to align with query patterns.
Option A is correct because partition elimination requires the predicate to be on the partitioning column. In this case, the queries likely do not filter on OrderDate, or the predicate is not sargable. Adding a clustered index on OrderDate would help if the queries filter on OrderDate, but the stem says the queries aggregate by month for the current year, so they likely have a WHERE clause on OrderDate. If partition elimination is not happening, the most common reason is that the partition function is not aligned with the query predicate. Re-creating the partition function with a different boundary may help if the current boundaries are not matching. However, the best action is to ensure the queries use the partition column in the WHERE clause. Since we cannot change the code, we can modify the partition function to align with the typical query pattern. Option B is wrong because creating views does not force partition elimination. Option C is wrong because columnstore indexes do not directly cause partition elimination. Option D is wrong because updating statistics does not fix partition elimination.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Update statistics for the Orders table.
Why it's wrong here
Does not affect partition elimination.
✗
Create a columnstore index on the Orders table.
Why it's wrong here
May improve scan performance but not partition elimination.
✓
Re-create the partition function with a different boundary type (e.g., RIGHT instead of LEFT) to align with query patterns.
Why this is correct
Changing boundary type can improve partition elimination for date range queries.
Related concept
Static NAT maps one inside address to one outside address.
✗
Create an indexed view that pre-aggregates sales by month.
Why it's wrong here
Does not address partition elimination.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this DP-300 question in full detail.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related DP-300 NAT questions on configuration and troubleshooting.
Monitor, configure, and optimize database resources — This question tests Monitor, configure, and optimize database resources — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Re-create the partition function with a different boundary type (e.g., RIGHT instead of LEFT) to align with query patterns. — Option A is correct because partition elimination requires the predicate to be on the partitioning column. In this case, the queries likely do not filter on OrderDate, or the predicate is not sargable. Adding a clustered index on OrderDate would help if the queries filter on OrderDate, but the stem says the queries aggregate by month for the current year, so they likely have a WHERE clause on OrderDate. If partition elimination is not happening, the most common reason is that the partition function is not aligned with the query predicate. Re-creating the partition function with a different boundary may help if the current boundaries are not matching. However, the best action is to ensure the queries use the partition column in the WHERE clause. Since we cannot change the code, we can modify the partition function to align with the typical query pattern. Option B is wrong because creating views does not force partition elimination. Option C is wrong because columnstore indexes do not directly cause partition elimination. Option D is wrong because updating statistics does not fix partition elimination.
What should I do if I get this DP-300 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related DP-300 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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