Investigate avoiding fetch of media info record (_bn)

[mitchellsundt]

Migrated to getodk/aggregate#42 by spacetelescope/github-issues-import

Originally reported on Google Code with ID 770

Can we avoid fetching any of the _bn records for the submissions data page?

I think we can construct the URL for the media without knowing this info. And we know
the media type from the form definition, so we know what treatment to do without getting
the exact contentType.

This would allow ODK Scan surveys to be presented/hosted in AppEngine and not hit the
60-second limit.

We would then only do explicit reads when accessing the media files, the form definition's
media list, and never when accessing the submission rows.

Reported by mitchellsundt on 2013-02-19 19:46:52

[mitchellsundt]

Migrated to opendatakit/aggregate#42 (comment) by spacetelescope/github-issues-import

Unfortunately, this would not allow null (missing media) to be reported directly. Instead,
a link would always be constructed which may or may not have any data.

The only work-around would be to change the data representation of a submission to
have a flag in the parent record indicating whether or not there was data in the _bn
table for this record. 

We could do the same optimization for the multiple-choice entries as well.

Reported by mitchellsundt on 2013-03-15 00:11:56

• Labels added: 2.0