dhis2-users team mailing list archive

["Wilson,Randy" <rwilson@xxxxxxx>]

Thanks to all of you..

I now have some great short term fixes and look forward to thinking more about the best approach over the longer term.  I like the idea of using this function to create "true" views dynamically as well as the tables Jason has created.   From the user perspective, the nice thing is that they can use the DHIS web interface to create useful dataelement and indicator groups - and then the function creates the views for them automatically - no need to write SQL queries.  We might want to add a check box in the dataelement/indicator group definition screens that users can check if they want the a materialized view created for the group.  The default would be no.  Then we can change the syntax in the function to select only those groups that are checked before looping through and creating the tables/views.

As Jason notes the main issue that brought us to build these tables was that the SQL syntax in the function uses the resource tables - to create a more detailed orgunit view (all reporting entities with the names of the entire hierarchy above them (sector, sub-district, district, province).  Many of the reports require these groupings of data and the pivot table drill-down/float-up capabilities are very helpful.  I'm not sure how we can get around the need to drop and rebuild these tables.

Randy


From: Lars Helge Øverland [mailto:larshelge@xxxxxxxxx]
Sent: Thursday, December 20, 2012 10:51 PM
To: Jason Pickering
Cc: Wilson,Randy; dhis2-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Dhis2-users] Help creating links to download materialized views

Okay. So with materialized view you are referring to a plain db table, right? I thought you meant creating a view with sql something like "create materialized view" but I can see that has not been implemented directly in postgres yet.

Anyway I think creating a dhis sql view per table is a reasonable work-around. It requires you only to create 20 objects, one time.

One alternative would be to create some sort of dhis sql report. But it would be very similar in nature and require some development for 2.11.  Another alternative would be just to expose database tables through the web api but that does not sound very nice or restful to me.

So if you are willing to create a sql view per table you can achieve 1.

Re 2 you can simply point directly to the sql views through the web api, for instance to the demo like this, for xml:

http://apps.dhis2.org/demo/api/sqlViews/dI68mLkP1wN/data.xml<http://apps.dhis2.org/demo/api/sqlViews/dI68mLkP1wN/data>

for csv:

http://apps.dhis2.org/demo/api/sqlViews/dI68mLkP1wN/data.csv

I have committed and backported to 2.10 representations for Excel and HTML, you can reach them after upgrading by using the extensions .xls and .html .

For web pages you can use plain links like this:

<a href="http://apps.dhis2.org/demo/api/sqlViews/dI68mLkP1wN/data.xml<http://apps.dhis2.org/demo/api/sqlViews/dI68mLkP1wN/data>">Download as XML</a> |
<a href="http://apps.dhis2.org/demo/api/sqlViews/dI68mLkP1wN/data.csv";>CSV</a> | etc

For 3, yes you can easily include these as resources. Just add a new one, give it a name, select "external URL" as type and point to the sql view URLs above.


For authentication you might get some tips from here:

http://dhis2.org/doc/snapshot/en/implementer/html/ch08s02.html#d5e600


You can download 2.10 latest from here in half an hour:

http://apps.dhis2.org/ci/job/dhis-web-2.10/lastSuccessfulBuild/artifact/dhis-2/dhis-web/dhis-web-portal/target/dhis.war





On Thu, Dec 20, 2012 at 5:28 PM, Jason Pickering <jason.p.pickering@xxxxxxxxx<mailto:jason.p.pickering@xxxxxxxxx>> wrote:
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<mailto: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<tel:%2B250788308835> (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.


_______________________________________________
Mailing list: https://launchpad.net/~dhis2-users
Post to     : dhis2-users@xxxxxxxxxxxxxxxxxxx<mailto:dhis2-users@xxxxxxxxxxxxxxxxxxx>
Unsubscribe : https://launchpad.net/~dhis2-users
More help   : https://help.launchpad.net/ListHelp


_______________________________________________
Mailing list: https://launchpad.net/~dhis2-users
Post to     : dhis2-users@xxxxxxxxxxxxxxxxxxx<mailto:dhis2-users@xxxxxxxxxxxxxxxxxxx>
Unsubscribe : https://launchpad.net/~dhis2-users
More help   : https://help.launchpad.net/ListHelp