How to open the Memory drilldown
From the Spotlight Client
- Select the connection from the left Connections pane.
- Click Monitor | Memory from the ribbon.
About the Memory drilldown
Investigate how Azure SQL Managed Instance is using physical memory.
Memory Areas chart
Shows the total amount of memory being used by Azure SQL Managed Instance’s caches over time.
Hit Rates chart
Shows the Hit Rates for the main Azure SQL Managed Instance caches.
A Hit Rate indicates the amount of work (I/O or compilations) that is being saved by caching information in memory.
Hit rates are shown for the following caches:
- Buffer Cache
- Procedure Cache - The hit rate for this cache will vary widely depending on how the application is written. This figure is averaged for all procedure cache object types except ad hoc SQL.
Spotlight calculates its hit rates using a differential sampling method. Unlike most Azure SQL Managed Instance monitors, it is not reporting the average hit rate since Azure SQL Managed Instance started.
Server Memory chart
Shows the total memory that Azure SQL Managed Instance is using, scaled against the target amount of memory it could use.
Cache chart
Shows the amount of memory allocated to the Buffer Cache and Procedure Cache over time.
The buffer cache is normally the largest memory cache used by Azure SQL Managed Instance.
It also shows the amount of memory allocated to Free Pages and Stolen Pages over time.
Buffer Cache Page Life Expectancy chart
This shows the current Page Life Expectancy.
Azure SQL Managed Instance holds recently accessed database pages in a memory area called the Buffer Cache. If a SQL process needs to access a database page and that page is already in the buffer cache, then Azure SQL Managed Instance does not need to read the page from disk. This can save a significant amount of disk I/O and can speed up queries significantly.
Page Life Expectancy is the length of time in seconds that a database page will stay in the buffer cache without references. Large values mean that pages are staying in the buffer cache longer and that the buffer cache is behaving efficiently. Small values mean that pages are being flushed out of the cache within a small period of time and that the buffer cache is not being effective. Microsoft recommends 300 seconds as the minimum value for this; any less is indicative of a shortage of memory.