dhis2-devs team mailing list archive

[Lars Helge Øverland <larshelge@xxxxxxxxx>]

>
> OK.  I've taken a really long look at the schema and here's my first
> pass at understanding the HISP approach.  It seems to me that if data
> elements appear in different datasets, there is therefore no way to be
> able to link any particular datavalue with a dataset.
>
> For example if there is DataSet DS_a with DataElements DE_a, DE_b and DE_c.
>
> And there is DataSet DS_b with DataElements DE_a and DE_d.
>
> If we were to try and export DataValues from dataset DS_a, the best we
> can do is identify all DataValues with DateElement types DE_a, DE_b
> and DE_c.  There will be overlap with the elements of DS_b.  Put
> differently, if there are 100 values in total and we export DS_a and
> DS_b we might end up with 110 values.
>
> The DataValue only knows its source, dataelement and period, not the
> dataset it belongs to.
>
> In fact the idea of a DataSet becomes quite a "weak" one for grouping
> datavalues.
>
> In which case the only sensible way of identifying sets of datavalues
> is by organisation unit and/or by period.  Is this correct?
>


All of this is correct.

Though there is no data model enforcement, one orgunit cannot enter data for
the same data element in different data sets. This would simply overwrite
the existing data, which again implies that we won't end up with duplicates.