For example, if I want to only requeue all failed transcodes, it shouldn't be necessary to basically select all transcodeable rows from the image table, then look them up in the transcode table to get their state.

We should be able to query for transcode.transcode_time_error IS NOT NULL and then use transcode_image_name to work out what we want to requeue.

We may be able do similar for stalled and missing by doing an SQL query for time_addjob; there is an index covering that column