--sap memory management has also different memory area and also buffer area.
using that memory area
and buffer area sap do thier activity.
--this daigram represents for only one instance.ex-in 000 ,001,003 it belongs to any one instance.
--VIRTUAL MEMORY(VM):-in sap system main memory is not enough to do processing it is very
expensive.
so we have small area inthe hard drive called swap area so our swap area and amin memory combine
together and form virtual memory.so VM is the memory available to sap system.
--virtual memory is divided into two parts local memroy an dshared memory.
--LOCAL MEMORY:-all the work process has some memory indivisual i.e local memory as seen in fig.
--SHARED MEMROY:-all the work has common memory called shared memory.
--all this wp forward by dispacther.one dispacther start all this wp.
--WP MULTIPLEXING:-multiple wp invlove doing one transaction.
--whatever i am working on i have to copy on shared memory,so when another wp comes to me i can
put all these things from shared memory to new wp.this is called roll out .
---then from shared memroy all the things which we we are working on copy to another wp is called roll
in process.
--
--roll area information and page area info we can't hold permanently when system use multiplexing so it
has to move to shared memory.
-we can move some itmes of shared memory to sap buffers.
--sap buffers connect to all the work process.
--information goes from one wp to another wp through shared memory during transfer it stored in roll
buffer.
--my user contex wil be save here in roll buffer.
--if i can't use roll buffer 15min or 20 min than information of roll buffer copy in sap roll file.
--if local memory if full than you can process it in extended memory means unfinished transaction.
--local memory has component called heap memory/private memory means nno body can see that.
--if local and extended memory also full than we can use heap memory.
--in st02 t code we can see all the sap memory used by the system.
--roll memory has two component 1)roll_first 2)tota roll_area.
--local memory has two component roll area/memory and heap area.
--we decide allocation of roll first memory by changing its parameter.ex-ztta/roll_first is used.
--t code rz11 to find out real parameter
---minimum/current parameter is 1 means 1024 bytes
--for dailog wp first we can use roll area1 after its fill we can use extended meory than roll area2(total
roll area- roll area1) after that we can use private memory.
--for non dailog wp first entire roll area is used ex-roll area1 and roll area2 after private
--there is parameter which sets the ammount of work process that can be used bases on
ztta/roll_extension.
--after private memory fill we have to restart the work process.
--through mapping data can be acess fast.
---------------------------import export internal table into memory-------------------------------------------
-- i don't want to call from table ce190000 MANY time so i have import internal table into memory id
i.e import it_cel19000 to it_cel19000[] from memory id 'DPR_ZFI_SALES'.
-- In the first call its empty
---select from database to filling.
and then append some field
append ls_cel1900_kaufn to it_cel1900.
---and then export to memory id.
export it_cel1900 from it_cel1900[] to memory id 'DPRO_ZFI_SALES'.
