Oddity With User Write Count In dm_db_index_usage_stats

Shaun J. Stuart looks at an oddity with the user_updates column on sys.dm_db_index_usage_stats:

This pulls both reads and writes from the sys.dm_db_index_usage_stats dynamic management view. A read is defined as either a seekscan, or lookup and a write is defined as an update. All seemed good until I noticed something strange. One of the top written to tables was, based on our naming convention, a lookup table. That seemed odd. A lookup table should have lots of reads, but only few writes. The query above showed my lookup table had almost twice as many writes as reads!

I dug around a bit and found two stored procedures that referenced that particular table. I checked them out, but nothing seemed out of the ordinary to me, so I dug a little deeper and discovered something strange: theuser_updates value of sys.dm_db_index_usage_stats can get incremented even when there is no actual update to the table!!

Read on for the explanation.

Related Posts

Sizing Azure SQL Database

Arun Sirpal takes us through finding the right size for Azure SQL Database: Do you want to identify the correct Service Tier and Compute Size ( was once known as performance level) for your Azure SQL Database? How would you go about it? Would you use the DTU (Database Transaction Unit) calculator? What about the […]

Read More

Cleaning Up After Yourself in Azure Data Factory

Rayis Imayev shows how you can automatically delete old files in Azure Data Factory: File management may not be at the top of my list of priorities during data integration projects. I assume that once I learn enough about sourcing data systems and target destination platform, I’m ready to design and build a data integration […]

Read More

Categories

October 2018
MTWTFSS
« Sep Nov »
1234567
891011121314
15161718192021
22232425262728
293031