By default , single SAP HANA query can consume 100% of available memory. If you want to safeguard your system from uncontrolled expensive queries then it’s a good idea to limit the memory consumption of single statement per host.
Starting HANA SP08 SAP introduced parameter statement_memory_limit to restrict the query at predefined memory consumption limit.
Queries will be aborted with OOM dump ("compositelimit_oom OR [MEMORY_LIMIT_VIOLATION] ") , if it reaches the limit specified by this parameter - statement_memory_limit .
Requirement: You want to limit query from consuming limitless HANA memory.
Prerequisite: You need database user with INIFILE ADMIN system privilege assigned.You also need statement memory tracking feature enabled. You need to change following parameters , these parameters do not need restart.
global.ini > [resource_tracking] > enable_tracking = on
global.ini > [resource_tracking] > memory_tracking = on
This will populate the MEMORY_SIZE column of expensive statement trace( M_EXPENSIVE_STATEMENTS)
- Connect to HANA system and open SQL console in HANA studio
- Execute following SQL
OR change following parameter.Administration perspective > Configuration > global.ini > [memorymanager] -> statement_memory_limit = <maximum_memory_allocation_in_gb>
If you want to disable this parameter , simply remove the parameter.
Starting SP09 we got flexibility this parameter in accordance of percentage of global allocation limit. Below parameter make sure that the statement_memory_limit only takes effect if the overall SAP HANA memory allocation exceeds a defined percentage of the global allocation limit:
global.ini > [memorymanager] > statement_memory_limit_threshold = <percentage_of_global_allocation_limit>