COPA Delta Mechanism

Question

Hi All,
Can any one explain about Delta Mechanism in COPA ie.,
How delta works in COPA,
From where the delta record are picked,
When the Delta Queue is filled,
what is Safety Delta,
What is Relignment and when we go for that, etc.....
Thanks in Advance,
Regards
Ramakrishna Kamurthy

Answer 1

Hi Ramakrishana,
Up to and including Plug-In Release PI2003.1, a DataSource is only
defined in the current client of the R/3 System. This means that a
DataSource can only be extracted from this client. The DataSource has a
timestamp for the delta method, and this timestamp is only valid for th
current client. This timestamp is managed by Profitability Analysis.
With Plug-In Release PI2004.1 (Release 4.0 and higher), timestamp
management was converted to a new method, called generic delta. This
method works in connection with an SAP BW system with Release 2.0 and
higher. With this method, timestamp management is no longer performed b
Profitability Analysis, but instead by the Service API (interface on th
R/3 side between Profitability Analysis and SAP BW). Exclusively in
Release 3.1I, Profitability Analysis continues to support timestamp
management.
Compared to timestamp management in Profitability Analysis, the generic
delta allows for several enhancements:
o   You can apply the delta method simultaneously using the same
     DataSource from more than one R/3 System client because a separate
     timestamp is saved for each logical system.
o   You can apply the delta method for the same R/3 System client
     simultaneously using the same DataSource from several SAP BW
     systems.
o   You can perform several initializations of the delta method with
     different selections using the same DataSource from a given SAP BW
     system for the same R/3 System client.
o   The DataSource commands the Delta Init Simulation mode. With
     timestamp management in Profitability Analysis, this mode had to be
      implemented using the Simulate Delta Method Initialization function
      (see SAP Note 408366).
  For more information on the generic delta, see Delta Transfer, whereby
  the steps of the Specify Generic Delta for a DataSource section are
  performed automatically for Profitability Analysis when a DataSource is
  created. For this, the field determining the delta is taken as the
  timestamp for Profitability Analysis (TIMESTMP), and the timestamp is
  stored for summarization levels and line item tables. However, in
  contrast to generic DataSources, the TIMESTMP field is not generated in
  the extraction structure because this is not necessary for DataSources
  in Profitability Analysis. As with timestamp management in Profitabilit
  Analysis, an upper limit of 30 minutes is set as the safety interval.
  You find the timestamp of a DataSource for the delta method in the
  current logical system either in the Header Information for the
  DataSource using the IMG activity Display Detailed Information on
  DataSource or using the IMG activity Check Delta Queue in the Extractor
  IMG. The timestamp is shown here when you choose the selection button i
  the Status column for the combination of DataSource and SAP BW system.
  DataSources created after implementing PI2004.1 automatically apply the
  new method. DataSources that were created in Plug-In releases prior to
  PI2004.1 still continue to use timestamp management in Profitability
  Analysis but can be converted to the generic delta. For this, an
  additional selection option Convert to Generic Delta appears in the
  selection screen of the IMG activity Create Transaction Data DataSource
  when a DataSource with timestamp management in Profitability Analysis i
  entered. Conversion from the generic delta to timestamp management in
  Profitability Analysis is not supported.
  Conversion is only possible for DataSources that are defined in the
  current client of the R/3 system and for which the delta method has
  already been successfully initialized or for which a delta update has
  successfully been performed. This is the case once the DataSource has
  the replication status Update successful. Furthermore, no realignments
  should have been performed since the last delta update.
For the conversion, the timestamp for the current R/3 System client is
transferred from Profitability Analysis into the timestamp of the
generic delta. In this way, the transition is seamless, enabling you to
continue to perform delta updates after the conversion. If delta updates
are to be performed from different R/3 System clients for this
DataSource, you first need to initialize the delta method for these
clients.
The conversion must be performed separately in each R/3 System because
the timestamp information is always dependent on the current R/3 System
and is reset during the transport. If, however, a converted DataSource
is inadvertently transported into a system in which it has not yet been
converted, delta extraction will no longer work in the target system
because the timestamp information is deleted during the import into the
target system and is not converted to the timestamp information of the
generic delta. If in this instance no new delta initialization is going
to be performed in the target system for the DataSource, you can execute
program ZZUPD_ROOSGENDLM_FROM_TKEBWTS from SAP Note 776151 for the
DataSource. This program reconstructs the current time stamp information
from the information for the data packages transported thus far and
enters this time stamp information into the time stamp information for
the generic delta. Once this program has been applied, delta extraction
should work again. Normally, however, you should ensure during the
transport that the DataSource uses the same logic in the source system
and the target system.
After the conversion, the DataSource must be replicated again from the
SAP BW system.
A successful conversion is recorded in the notes on the DataSource,
which you can view in the IMG activity Display Detailed Information on
DataSource.
Since the generic delta does not offer any other log functions apart
from the timestamp information (status: Plug-In Release PI2004.1),
Profitability Analysis still logs the delta initialization requests or
delta requests. However, the information logged, in particular the
timestamps, only has a statistical character because the actual
timestamp management occurs in the generic delta. Since the delta method  can be performed simultaneously for the same R/3 System client using the
  generic delta from several SAP BW systems, the information logged is
  stored for each logical system (in R/3) and SAP BW system. When a delta
  initialization is simulated, only the timestamp of the generic delta is
  set; Profitability Analysis is not called. Consequently, no information
  can be logged in this case. Messages concerning a DataSource are only
  saved for each logical system (in R/3). You can use the IMG activity
  Display Detailed Information on DataSource to view the information
  logged.
  Another enhancement from Plug-In Release PI2004.1 means that you can no
  longer exclusively perform full updates for DataSources of the Extractor
  Checker of the Service API that have recently been created or converted
  to the generic delta. The following update modes are possible:
  o   F - Full update: Transfer of all requested data
  o   D - Delta: Transfer of the delta since the last request
  o   R - Repeat transfer of a data package
  o   C - Initialization of the delta transfer
  o   S - Simulation of the initialization of the delta transfer
  In the case of all update modes other than F, you have to specify an SAP
  BW system as the target system so that the corresponding timestamp
  and/or selection information for reading the data is found. The Read
  only parameter is set automatically and indicates that no timestamp
  information is changed and that Profitability Analysis does not log the
  request.
  Update mode I (transfer of an opening balance for non-cumulative values)
  is not supported by Profitability Analysis.
Assign Points if useful
Regards
Venkata Devaraj