How to monitor the memory consumption used by the cold data (paged attributes)?

Thursday, July 12th, 2018

On table level the monitoring capabilities allow to only show how much data is loaded into memory per partition/per column. As technically Data Aging in SAP HANA is using Paged Attributes for cold partitions only during the access of these data it needs to be loaded to Memory. There is a dedicated Cache area with configurable size, which allows improving the performance of consecutive accesses to same data.

  • The System Views M_MEMORY_OBJECT_DISPOSITIONS and M_MEMORY_OBJECTS are available to globally monitor the memory consumption of the paged attributes.
  • M_MEMORY_OBJECT_DISPOSITIONS shows how much memory is currently consumed by the paged attributes (PAGE_LOADABLE_COLUMNS_OBJECT_SIZE) and how many paged attributes are currently loaded into memory (PAGE_LOADABLE_COLUMNS_OBJECT_COUNT).
  • M_MEMORY_OBJECTS shows how many paged attributes (PAGE_LOADABLE_COLUMNS_LIMIT_SHRINK_COUNT) were unloaded from the memory since the last restart and their size (PAGE_LOADABLE_COLUMNS_LIMIT_SHRINK_SIZE) e.g. due to configured limit reached. This view shows mainly the turnaround of the cold data in memory.