dhis2-users team mailing list archive

[Jason Pickering <jason.p.pickering@xxxxxxxxx>]

Hi Randy and Lars,
The fundemental problem is that view which they were using are linked to
the resource tables. These tables need to be regenerated, and when they are
regenerated, the tables are dropped and recreated. If views are linked to
these tables, the resource table regeneration cannot take place, because
the database forbids the table to be dropped, because there are linked
views. DHIS2 fails silently and only says "Resource tables generating..."
or something like that. I think we have described this problem on the list
before and I am sure you are aware of it.

So, to get around this problem, we use stored procedures to materialize the
views, and then as Randy indicates, users can get to them through ODBC.

I guess it could be done Randy by creating an SQL View of the materialized
view. This does not really make a whole lot of sense, but it could be done.
So, if you create an SQL view in DHIS2 of "SELECT * FROM _materalized
view;" you will get a new materialized view available, as Lars points out,
through the API. A bit wasteful really but certainly possible.

The "elegant" part which Randy mentions is that we do not define many
seperate views, but dynamically define the tables based on data element
groups. The views are very similar, they just differ in the data elements
which should be presented to the users. So, instead of maintaining like
20 separate similar views, we have just done the same thing with one single
stored procedure instead. Second option then would be to have
these separate 20 (or whatever the number is) views as DHIS2 SQL views.
Again, not very elegant.

Third option which I see (which I think is the best option) is to reflect
SQL views out of DHIS2 without ever materializing them. I think there
should be an option for "materialize" for each SQL view. If it is not
checked, the view would be produced dynamically at the time of request.
Again, not a very elegant solution for this problem, because we would still
need 20 separate "SELECT * FROM _materialized_view1", "SELECT * FROM
_materialized_view2", but at least we would not write the materalized view
twice.

Fourth option (maybe a bit limiting) is to create the same SQL View type of
functionality for tables, lets call it a table reflector, which would
simply reflect a table as JSON, XML, CSV or whatever. The user could be
presented with a list of tables in the system, and simply choose the one
you want (in our case, one of the materialized views) and then they would
be available somehow through the API.

Fifth option, is some external report. In Nigeria, we use R for this
purpose actually, and it is relatively straightforward. Other things like
PHP, Python or Birt could be used pretty easily as well.

Just a bit of a grab-bag, but maybe there will be some possible solution in
there.

Regards,
Jason




On Thu, Dec 20, 2012 at 1:58 PM, Wilson,Randy <rwilson@xxxxxxx> wrote:

>  In Rwanda we have found report tables and MyDatamart inadequate for the
> needs of many of the central level health programs.  What they want is a
> dump of all the datavalues in *specific* *dataelement and indicator groups
> * along with the related orgunit hierarchy.  We originally were doing
> this using SQL views, under Data Administration, however some of the views
> are built on one another so when the Datamart and Resource table procedures
> run they is unable to drop the views before re-creating them…. And
> consequently neither process runs.****
>
> ** **
>
> Jason Pickering has helped us develop an elegant function that gets around
> the view issue, and creates materialized views for all dataelement groups:
> special tables that are refreshed every night through a chron job (just
> like the datamart).  This gives us exactly what the users want – they
> generally link to the tables with ODBC connection using an excel pivot
> table – and because they are only retrieving the dataelement groups they
> want the file is not too big.  Unfortunately, this only works on the local
> area network – refreshing the pivot tables over the network is likely to be
> too slow, and our security settings don’t enable a remote ODBC connection.
> ****
>
> ** **
>
> We are now beginning to explore the DHIS-2 API to create a portal for
> users to access DHIS-2 objects.  I see that SQL views are exposed through
> this API, but for the reasons stated above we can’t rely on them.  Here is
> where we need help:****
>
> **1.       **Is there a way to expose other tables in the API? ****
>
> **2.       **Does anyone have some sample HTML code that we could use to
> list these special tables (they all start with _*view*_) in the portal
> and download them as xls, csv or xml?  Similar to what is shown in the
> DHIS-2 portal demo for downloading tables.****
>
> **3.       **Could we include the links to these tables as resources in
> users’ dashboards?****
>
> ** **
>
> *Randy Wilson*****
>
> Senior HMIS and Data Use Advisor****
>
> Rwanda/IHSSP****
>
> Management Sciences for Health****
>
> BOX 371
> Kigali, Rwanda
> +250788308835 (mobile)
> Skype name (wilsonrandy_us)****
>
> www.msh.org<http://www.msh.org/?utm_source=2012-10-15+MSH+internal+announce+email+signature&utm_campaign=iemailsig&utm_medium=email>
>  ****
>
> *Stronger health systems. Greater health impact.*****
>
> ** **
>
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