Safety interval upper/lower limit of a Delta selection (2)

PS: Previous articlesBlogI mentioned it, but it is still a little difficult to apply it well, so I will discuss these small functions.

Problem Background:

Currently, a smallCaseIs aboutDeltaSelf-built data sources of the Mechanism are always unable to extract data.

Cause:

BW's delta mechanism is to record a timestamp in the system, such as 20110531, which is the date of the last extraction.

When the Delta information package is executed in 20110601, data from ersda During the Period of 20110601-20110601 will be extracted.

Just right, the time it took to catch up with the processing chain to execute the information package was about 2 o'clock in the morning. That is to say, data was not input on January 1, June 1, and the time stamp showed that the data had been drawn, only new data of 20110602-20110602 will be extracted during the extraction in June 2.

Therefore, we will consider setting the upper and lower security limits.

Which means,6Month1During daily extraction20110524-20110601 of the data, so there will be repeated data, but there will be no such serious loss.

It means that the data of 20110531-10510531 will be loaded during the extraction in December 31, June 1. This is the best setting method, that is, by postponing the timestamp, the data will be deducted from the one-day creation time.

This phenomenon can be easily seen from rsa7, where the timestamp is displayed as 20110531. In June 2, when the timestamp is 20110601, 20110601 of the data is extracted.