Arun,
After reading your question, I started thinking what if the the partner profile setting and the BD51 contradict each other. I came across something that should be useful for your understanding as well.
ALE inbound processing splits the IDoc packets into individual IDocs; this results in an overhead such as,. the same programs, user contexts, and database tables are read multiple times. Trigger by Background Program It is important to note that if the receiver system uses trigger immediately option, whether IDocs are processed in the package or not depends on the character of the Inbound function module (if function module supports mass processing or not is defined in transaction BD51). If mass processing is not supported, IDocs will be posted one by one. Inbound IDocs and IDoc packets are first saved in the database into single IDocs. Single IDocs can be put into packets and then processed this functionality is provided by report RBDAPP01, which allows you to specify the package size for the RFC call. This type of package processing is valid for all IDoc types as there are no special requirements for the inbound function module. However there is limited optimization potential here as a commit is triggered for every processed IDoc because the ALE layer calls the function module several times in the same dialog process. This does however reduce the administrative load on the R/3 System because if packaging was not implemented, each IDoc would be processed in a new dialog process meaning, the same programs, user contexts, and database tables are read multiple times. If you use function modules that can process IDocs in mass, this has a significant optimization potential as overhead is reduced significantly. This type of package processing can be used depending on the configuration of the Inbound function module used for an IDoc. This can be checked via transaction BD51. If the input type value is set to ‘0’ the function module is enabled for mass processing. In this case, one commit is triggered for all IDocs belonging to a packet.
V.