What is page life expectancy in SAP BC-DB-MSS - Microsoft SQL Server?

SAP Term: page life expectancy

• Component: BC-DB-MSS

• Component Name: Microsoft SQL Server

• Description: A measure of the efficiency of SQL Server memory. SQL Server allocates a memory area called a buffer pool. This memory is allocated in units of 8k pages. These pages are used to make the data access more efficient. So if a user gets data from the database, it is copied to a memory page, in case another request comes in for the same data. But if there are not enough free pages available, SQL Server replaces flushes out some pages when necessary. The page life expectancy is the amount of time seconds that an average page will stay in memory before being flushed out.

Smart SAP Assistant

• Key Concepts: 
  Page Life Expectancy (PLE) is a metric used to measure the amount of time a page of data remains in the buffer pool of a Microsoft SQL Server database. It is an important metric for monitoring the performance of a database, as it indicates how often pages are being read from disk. A low PLE value can indicate that the buffer pool is not large enough to hold all the data that needs to be accessed, resulting in frequent disk reads.
  
  How to use it: 
  To measure PLE, you can use the sys.dm_os_performance_counters view in Microsoft SQL Server. This view contains a row for each performance counter, including PLE. The value of this counter is updated every second and can be used to monitor the performance of the database over time.
  
  Tips & Tricks: 
  If you find that your PLE is consistently low, it may be an indication that your buffer pool is too small and needs to be increased. Additionally, you can use the sys.dm_os_buffer_descriptors view to identify which pages are being read from disk most frequently and take steps to reduce their frequency of access.
  
  Related Information: 
  For more information on page life expectancy and other performance metrics, please refer to Microsoft's documentation on sys.dm_os_performance_counters and sys.dm_os_buffer_descriptors. Additionally, there are many third-party tools available for monitoring and analyzing database performance metrics such as PLE.