What is the significance of Safety Upper Limit and Lower Limit

Question

Hello Experts,
I was trying to create a generic datasouce in rso2 , while setting the delta specific field I have selected date field and I need to know the significance of other two input fields provided over there:
Safety Interval Upper Limit.
Safety Interval Lower Limit.
and check box Real Time Enable.
Thanks,
Vijay

Answer 1

Hi Vijay
Safety Interval Upper Limit of Delta Selection This field is used by DataSources that determine their delta generically using a repetitively-increasing field in the extract structure. The field contains the discrepancy between the current maximum when the delta or delta init extraction took place and the data that has actually been read. Leaving the value blank increases the risk that the system could not extract records arising during extraction. Example: A time stamp is used to determine the delta. The time stamp that was last read is 12:00:00. The next delta extraction begins at 12:30:00. In this case, the selection interval is 12:00:00 to 12:30:00. At the end of extraction, the pointer is set to 12:30:00. A record - for example, a document- is created at 12:25 but not saved until 12:35. It is not contained in the extracted data but, because of its time stamp, is not extracted the next time either. For this reason, the safety margin between read and transferred data must always be larger than the maximum length of time that it takes to create a record for this DataSource (with a time stamp delta), or it must display an interval that is sufficiently large (for determining delta using a serial number). Safety Interval Lower Limit This field contains the value taken from the highest value of the previous delta extraction to determine the lowest value of the time stamp for the next delta extraction. For example: A time stamp is used to determine a delta. The extracted data is master data: The system only transfers after-images that overwrite the status in the BW. Therefore, a record can be extracted into the BW for such data without any problems. Taking this into account, the current time stamp can always be used as the upper limit when extracting: The lower limit of the next extraction is not seamlessly joined to the upper limit of the last extraction. Instead, its value is the same as this upper limit minus a safety margin. This safety margin needs to be big enough to contain all values in the extraction which already had a time stamp when the last extraction was carried out but which were not read. Not surprisingly, records can be transferred twice. However, for the reasons above, this is unavoidable. these are used to determining the delta in a datasource: 1. Time stamp - The field is a DEC15 field which always contains the time stamp of the last change to a record in the local time format. 2. Calendar day - The field is a DATS8 field which always contains the day of the last change. 3. Numerical pointer - The field contains another numerical pointer that appears with each new record .
also dwload this How to Generic Delta doc https://www.sdn.sap.com/irj/servlet/prt/portal/prtroot/docs/library/uuid/84bf4d68-0601-0010-13b5-b062adbb3e33
2.
You can determine the upper limit of the time. To do this, you specify a time period relative to the current date. The time unit for the time period can be specified in days, weeks, months, quarters, years, posting periods, or fiscal years.
The upper limit can also be rounded down to the end of a time period by selecting another, additional time unit, so that, for example, only complete months or years can be archived when a date field is selected as a selection characteristic for the time slice. The time slice defined in this way contains the complete time period before the upper limit calculated.
1. If delta field is Date (Record Create Date or change date), then use Upper Limit of 1 day.
This will load Delta in BW as of yesterday. Leave Lower limit blank.
2. If delta field is Time Stamp, then use Upper Limit of equal to 1800 Seconds (30 minutes).
This will load Delta in BW as of 30 minutes old. Leave Lower limit blank.
3. If delta field is a Numeric Pointer i.e. generated record # like in GLPCA table, then use
Lower Limit. Use count 10-100. Leave upper limit blank. If value 10 is used then last 10
records will be loaded again. If a record is created when load was running, those records
may get lost. To prevent this situation, lower limit can be used to backup the starting
sequence number. This may result in some records being processed more than once;
therefore, be sure this DataSources is only feeding an ODS Object
Hope this will help you
Thanks & Regards
Kiran