Delta generic datasource

[Former Member]

Hi gurus,

currently we have a problem with a delta generic datasource. We have just read the HOWTO document "create a generic datasource" but we have some questions about it.

1) Using the lower and upper limits, there is a difference between a blank value and a zero value?

2) Can you suggest the best configuration to this case: we have to load every morning datas of the previous day. We have think to put an upper limit of 1 and a lower limit of 0 (or blank... we don't know if there is a difference between this 2 kind of values)

Thanks a lot

[Former Member]

Safety Interval Upper Limit of Delta Selection

This field is used by DataSources that determine their delta genericall

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 actuall

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.

Assign points if useful

Regards

Venkata Devaraj

[Former Member]

Yep, wasn't very useful because this help's text contains some examples using the time, but I have to realize an extraction using the calendar days.

Can someone give me an example using the date instead of the time and clarify me the difference between 0 and blank value inside the upper/lower limit value?

Bye

[Former Member]

Hi,

Hope the below would be of use:

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