Export/Import memory

[sukhdev_kaloor]

Hi,

what is the difference between Export/Import buffer

and Exp./Imp.SHM buffer

regards,

dev

[Former Member]

Hi Dev,

Parameter 'rsdb/esm/buffersize_kb' controls the size of the exp/imp SHM buffer.

Documentation from RZ11 for this parameter is as follows:

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---

The parameter defines the size of the ESM buffer in kB. The buffer

provides data storage in Shared Memory and is addressed with the ABAP

commands EXPORT TO / IMPORT FROM SHARED MEMORY und DELETE FROM

SHARED MEMORY. The commands are only effective locally; the buffers

of external application servers are not changed.

If the buffer is full, no further objects can be stored in the buffer.

-

---

On the other hand for the Export/Import buffer the relevant parameter is rsdb/obj/buffersize, for which documentation is as follows:

-

---

This parameter sets the size of the import /export buffer (KB).

The buffer is used for data storage in the shared memory and is

accessed using the ABAP commands EXPORT TO/IMPORT FROM SHARED BUFFER

and DELETE FROM SHARED BUFFER. The commands only affect the local

system. Buffers on external application servers are not

changed. If the buffer is full, old buffer objects are kicked out

when new objects are exported to the buffer.

-

---

The last sentence for each is different. Parameter values and some more information are listed in SAP note #702728.

Regards, Mark

[raguraman_c]

Hi Dev,

This will be useful.

Whenever a user session is created during any transactions, objects are created

in memory. If another user is accessing the same object another copy is

created in the memory - which means accessing objects is one copy per

user per session (Session Memory).

Until before SAP Application Server 6.40 these objects cannot accessed

by other sessions or other programs. The concept of Shared Memory

enables to access this memory if the object is not locked by that

session. SAP Provides a class for accessing shared memories -

CL_ABAP_MEMORY_AREA. Static methods are available in this class for

binding a session to the memory area.

What are the Advantages of Shared Memory?

~Data is kept only once in Memory.

~The Data will be in the memory as Memory Tables that reflect the

structure of Database table.

~Fast access at Main Memory Speed.

~Saves Memory (Saves Approximately 3MB Per user per Session.

More on Next Posting...

http://groups.google.com/group/DEVS_SAP

--Thanks and Regards,

Ragu

ERP,

Suzlon Energy Limted, Pune

+919370675797

I have no limits for others sky is only a reason

[Former Member]

Hi Sukhdev,

Data clusters that are exported to the export/import buffer by an ABAP program are only available (for import) by other ABAP programs in the current call sequence. An example of when this would be used is to pass data between programs executing in a particular user session.

Data clusters that are exported to export/import buffer SHM by an ABAP program are available to all programs executing on the application server. An example of when this would be used is when you require many users and programs to have access to a piece of data stored in memory.

We have used the latter to store an internal table in memory that was built from data in the database. Previously, many programs were accessing the same data over and over, and causing high I/O activity in the database. Now, on a daily basis, the data is read from the database and stored in an internal table in the export/import SHM area.

Gary

[Former Member]

I'm using export/import from buffer statement in a transformation in BW. Because it is only avaliable for current call sequence, I thought it would be removed from the buffer next time a DTP runs to load data. Yet, when I run the DTP the next day to load data, the internal table is stil lin the export/import buffer. So what is the definition of "current call sequence"? When does the data cluster get removed?

Regards,

[Former Member]

I'm using export/import from buffer statement in a transformation in BW. Because it is only avaliable for current call sequence, I thought it would be removed from the buffer next time a DTP runs to load data. Yet, when I run the DTP the next day to load data, the internal table is stil lin the export/import buffer. So what is the definition of "current call sequence"? When does the data cluster get removed?

Regards,

Dae