When the DS_TOTAL_MEMORY configuration parameter is set

When the DS_TOTAL_MEMORY configuration parameter is set, the database server checks whether the SHMTOTAL configuration parameter is set and then determines which formula to use to calculate the amount of decision-support memory.

When SHMTOTAL is set, the database server uses the following formula to calculate the amount of decision-support memory:
IF DS_TOTAL_MEMORY <= SHMTOTAL - nondecision_support_memory THEN
   decision_support_memory = DS_TOTAL_MEMORY
ELSE
    decision_support_memory = SHMTOTAL -
                  nondecision_support_memory

This algorithm effectively prevents you from setting DS_TOTAL_MEMORY to values that the database server cannot possibly allocate to decision-support memory.

When SHMTOTAL is not set, the database server sets decision-support memory equal to the value that you specified in DS_TOTAL_MEMORY.


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