Delta Mechanism for Generic Extractors

[Former Member]

How to enable Delta Mechanism for Generic Extractors

Ø 3 Types of Delta Mechanism for Generic Extraction

Ø 1. CALDAY 2. Time Stamp 3.Numaric Point

Ø Delta Mechanism with CALDAY: I have a table VBAK – VBELN, ERDAT, AUDAT, NETWR

Ø We can set up delta mechanism based on CALDAY (Data Source Capability) when we have changed Date filed in data source

Ø AUDAT – will give latest changed date

Ø    VBELN	Ø    ERDAT	Ø    AUDAT	Ø    NETWR
Ø    4965	Ø    01.01.2006	Ø    01.01.2006	Ø    5000
Ø    4966	Ø    02.01.2006	Ø    02.01.2006	Ø    1000
Ø    4967	Ø    05.02.2006	Ø    05.02.2006	Ø    15000
Ø    4968	Ø    06.07.2007	Ø    06.07.2007	Ø    20000
Ø    4965	Ø    01.01.2006	Ø    09.07.2007	Ø    9000

Ø If we run Initialization Delta on 03.01.2006 It will Pick 4965 & 4966

Ø If we run Delta on 05.02.2006 at night 12’o clock it will Pick 4967 records (previously loaded records date >& TILL  05.02.2006 date)

Ø If we run Delta on 10.07.2007 It will Pick 4968 & 4965

Ø Limitations of Delta Mechanism with CALDAY: Multiple Deltas cannot be run on same day because it will not consider time factor. If the Delta Mechanism set up with CALDAY we can run delta only once per day at the end of day

Ø 2. Delta Mechanism with Time Stamp: Since Delta is Time stamp; we can run the delta number of times. If you setup Delta with Time Stamp we need to have Time Stamp Field in the source (UPD_TMSTMP)

Ø 3.Delta Mechanism with Numeric Point: If we set the delta based on numeric Point, it can only recognizes the newly added records but not the modified records

Ø Safety Interval: Let’s assume your delta run on Sunday, Thursday and Saturday. And you last run was on Sunday and next Run is on Thursday.
In this case if you have set the lower limit to 1, the delta run of Thursday will fetch data from Saturday till Thursday.

"Delta management can take the lower limit from the last extraction.
The lower limit for safety interval contains the value that needs to be taken from the highest value of the previous extraction to obtain the lowest value of the following extraction." E.g: You can say Lower limit = Highest value of last extraction- safety interval.

Example: Lower Limit = 2, Upper Limit = 1

Example: Lower Limit = 0, Upper Limit = 0

           Tips:

Ø If delta field is Date (Record Create Date or change date), then use Upper Limit of 1 day. This will load Delta in BI as of yesterday. Leave Lower limit blank.

Ø If delta field is Time Stamp, then use Upper Limit of equal to 1800 Seconds (30 minutes). This will load Delta in BI as of 30 minutes old. Leave Lower limit blank.

NOTE: Safety interval should be set so that no document is missed – even if it was not stored in the DB table when the extraction took place.

     Select Delta type:

Ø New status for changed records (I.e. after-image); this can be used with Data target DSO (AIE).

Ø Additive Delta (I.e. aggregated data records) (ADD); Compatible with Info cube & DSO