Memory utilization shown on DMV sys.dm_db_resource_stats

  • salamlemon

    SSC-Addicted

    Points: 429

    Hi Guys,

    Can anyone please bit more details on what is this metric "avg_memory_usage_percent"exactly tell us in AzureSQL database?

    https://docs.microsoft.com/en-us/sql/relational-databases/system-dynamic-management-views/sys-dm-db-resource-stats-azure-sql-database?view=azuresqldb-current

    Documentation above says this.

    avg_memory_usage_percent

    decimal (5,2)

    Average memory utilization in percentage of the limit of the service tier.

    This includes memory used for buffer pool pages and storage of In-Memory OLTP objects.

     

    However, when I look at PLE counters on the server it's always giving more than lower expected value. Minimum value I'm expecting

    (Allocated Memory/4)*300   --I would expect on allocated 17GB memory it will be around 1200)

    The value is always way way over (9000+ ) than what should be minimum making me think there's no memory pressure. But avg_memory_usage_percent is telling me memory utilization is more than 97%.

    Any idea if the metric "avg_memory_usage_percent" is a good metric to look at memory utilization? If not is there anything else you guys are aware of?

     

     

    Regards,

    Salam

  • Grant Fritchey

    SSC Guru

    Points: 396247

    Memory use within Azure is pretty much the same as within SQL Server. Over time, it's going to go to near 100% allocation, always. It includes the cache, so your queries are going to load that up over time and, as you say, without any memory pressure, they'll stay there. I'd be surprised only if I saw memory percentages were lower than, say, 85% on a regular basis (ballpark figure, don't take that as some magical target).

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