Hi Paromita,
I think you are using message type MATMAS.
If you check the source code of program RBDMIDOC, you will see it calls RBDMIDOX and within
RBDMIDOX there is the following:
---------------------------
* the following is a list of message types that supports block reading
* and processing of change pointers (currently only MATMAS)
IF tbdme-refmestyp = 'MATMAS'.
flag_read_blocks = 'X'.
ELSE.
flag_read_blocks = space.
ENDIF.
---------------------------
So we can see the processing of message type MATMAS is in block and the block size is 50000.
CONSTANTS: c_block_size LIKE sy-tabix VALUE 50000.
So if you would like to change this behavior, you can change the source code of RBDMIDOX by either change the block size value, or remove the part of check listed above.
But keep in mind this change may lead to memory issues.
I hope above helps.
Kelly