Measures reported by HanaCtlgMemTest

Memory is a fundamental resource of the SAP HANA database. Understanding how the SAP HANA database requests, uses, and manages this resource is crucial to the understanding of SAP HANA. SAP HANA, across its different processes, reserves a pool of memory before actual use. This pool of allocated memory is preallocated from the operating system over time, up to a predefined global allocation limit, and is then efficiently used by SAP HANA as needed.

SAP HANA preallocates and manages its own memory pool, used for storing in-memory table data, thread stacks, temporary results, and other system data structures. When more memory is required for table growth or temporary computations, the SAP HANA memory manager obtains it from the pool. When the pool can’t satisfy the request, the memory manager increases the pool size by requesting more memory from the operating system, up to a predefined allocation limit.

Memory is a finite resource. Once the allocation limit has been reached and the pool is exhausted, the memory manager only allocates memory for internal operations after first giving up something else. However, it’s still possible that the memory manager needs more memory than is available leading to an out-of-memory failure. This may happen, for example, when too many concurrent transactions use up all memory, or when a complex query performs a cross join on large tables and creates a huge intermediate result that exceeds the available memory. HANA Catalog Memory Test helps administrators in this regard!

This test reports statistics related to the memory allocation and usgae in the target SAP HANA database server and promptly alerts administrators to potential memory contention which helps them to resolve the issue before it starts degrading the server performance.

Outputs of the test: One set of results for the target database server instance being monitored.

The measures made by this test are as follows: