After a lot of chewing on this subject, I have written another blueprint which think actually supercedes the previous blueprint on a related subject (https://blueprints.launchpad.net/dhis2/+spec/regex-validation).
The blueprint is available here https://blueprints.launchpad.net/dhis2/+spec/passthrough-query-executor.
My motivation here is to have a way to execute passthrough SELECT statements, that have been defined by somebody.
There are some security concerns here, which we will need to consider carefully.
As an example, lets assume that an administrator/data analyst defines a query to detect trailing spaces in organisationunit names. The query is stored and then executed as a passthrough query, with DHIS2 simply displaying the resut set of the query.
This method could also be used to store for instance the PivotSource queries, or really any arbitrary queries that would return some results.
The ability to export via CSV, Excel, HTML etc would be useful.
Jason P. Pickering