Duration of reclaiming disk space on very large tables (2.5+ billion rows)
I chose a different approach to reclaiming the diskspace. A lot of data was used for the pkey and prop_id_3df0d554fdfe92ee_idx indexes. It was possible to halt all writes to the table, during which time I issued a REINDEX command for the individual indexes. 

After rebuilding the indexes enough diskspace was reclaimed to allow a secondary table to be created based on the contents of the original table. Afterwards the original table was deleted and the second table renamed.