Display of 300,000 relation filtered list takes too much time (never completes)

[pombredanne]

When I try to filter in the web UI these relations by map type, it never completes.
When I do a CodebaseRelation.objects.filter(map_type="dwarf_compiled_paths")[:1000] on the same data this is returned in less than a second.

[pombredanne]

In terms of solution, we could avoid displaying the To/ resources that are not mapped entirely and instead just provide a link to the un-mapped To/ resources and another for the un-mapped From/ resources at the top of the page; and therefore only work from the relation table, avoiding any joins or iceberg queries.