Here is an excerpt from Oracle 8i Reference about SORT_AREA_SIZE:
"Increasing SORT_AREA_SIZE size improves the efficiency of large sorts. Multiple allocations never exist; there is only one memory area of SORT_AREA_SIZE for each user process at any time."
So does this mean for each user process, there could be a memory area of size SORT_AREA_SIZE that is dedicated to the user process for sorting? If so, if I have 3 user processes doing sorting at the same time, it could potentially use 3*SORT_AREA_SIZE memory?
What does it mean by "Multiple allocations never exist"? Does it mean each user process can only be allocated once for SORT_AREA_SIZE memory?
Yes you guessed it right. Each session will have its own SORT_AREA_SIZE. SORT_AREA_SIZE is not part of SGA.
Multiple allocations never exists means one session can have just one set of SORT_AREA_SIZE.
Total sort area size will be SORT_AREA_SIZE * no. of users doing sorts concurrently. I remember this was discuus here long ago.