View source for PartitionKeyStatistics (Diagnostic Log)

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'''Category:''' Maintenance & Security

'''Summary:''' Estimated storage size (KB) per logical partition key; flags storage skew.

== Overview ==
PartitionKeyStatistics is a diagnostic log table that logs logical partition key statistics in estimated KB, showing the approximate storage size consumed by each partition key value. It is the primary tool for troubleshooting storage skew — where one or a few partition key values approach the 20 GB logical partition storage limit while others remain nearly empty.

== More Info & Links ==
* [https://learn.microsoft.com/en-us/azure/cosmos-db/monitor-resource-logs Microsoft Learn: Monitor and troubleshoot using diagnostic logs]

== DP-420 Style Practice Questions ==
'''Q1.''' What does the PartitionKeyStatistics diagnostic log table report?
* A. Estimated storage size (in KB) consumed by each logical partition key value
* B. Per-second RU/s consumption per partition key
* C. The account's consistency level history
* D. The list of regions enabled for multi-region writes

'''Q2.''' What problem is PartitionKeyStatistics most useful for troubleshooting?
* A. Storage skew, where some partition key values approach the logical partition storage limit
* B. Query RU cost estimation
* C. Change feed processor lag
* D. 429 throttling error rates

== Answer Key ==
''Answers are listed at the very end so you can attempt the questions first.''

* '''Q1 (PartitionKeyStatistics (Diagnostic Log)):''' A. Estimated storage size (in KB) consumed by each logical partition key value — PartitionKeyStatistics reports estimated storage size per partition key, in KB.
* '''Q2 (PartitionKeyStatistics (Diagnostic Log)):''' A. Storage skew, where some partition key values approach the logical partition storage limit — This table helps identify storage skew by showing which partition key values are approaching the 20 GB logical partition limit.

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''DP-420: Designing and Implementing Cloud-Native Applications Using Microsoft Azure Cosmos DB — term detail page''

[[Category:DP-420 Terminology]]
[[Category:Maintenance & Security]]