Added indices on foreign key columns.
Added indices on foreign key columns.


Former-commit-id: c6404fa76e2bf40c0f65bf18ba7af2b3cf2ba396 [formerly f638a9d1784214cda751481feb75eb4865202d31]
Former-commit-id: fddb534820dac8a659416d82d9d6f2bbdf3de638
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine