[ODK Community] Cascade select slowing/freezing phones

Make sure you are using the latest 1.2 update (rev 1020).

The software is about as efficient as it can get at this point. Per an
earlier post about autocomplete widgets, for very large data sets, it would
be useful to have this done in an external app where the data can be held
in a database and selectively presented to the user. Alternatively, there
have been recent additions to the javarosa engine that allow the XPath
expression to be processed 'in bulk' to produce the list of filtered
values. The problem in the software is that there is a rather massive
nested loop within javarosa that does the individual evaluations of the
XPath expression. Bulk processing backed by a database would make the
processing far more efficient.

Since ODK2 will be natively backed by a database, we are not planning to
develop this widget in ODK1. But ODK2 and that functionality within it is
a ways off...

Mitch

ยทยทยท On Wed, Nov 21, 2012 at 1:16 AM, wrote:

Thank you for adding Cascading selects to v1.2, much needed and long
awaited.

However, in our first implementation of cascading selects, we have found
that it slows down the survey immensely - leading to up to a minute delay
between swiping to the next page and the next page appearing. Some of of
our less powerful phones completely freeze/hang. We are using lower end
Samsungs (Galaxy Mini and Galaxy Y) and Ideos. Our cascading list is 40
sublocations => 400 villages => 1000 waterpoints.

Is this just a hardware issue? Or can something be done on the software
side?

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Mitch Sundt
Software Engineer
University of Washington
mitchellsundt@gmail.com