One thing that I've run across is when doing a select on a large table with serial or indexed timestamps, ordered by that column is that the plans are horrible

One thing that I've run across is when doing a select on a large table with serial or indexed timestamps, ordered by that column is that the plans are horrible when the criteria you're using are unexpectedly rare, even if there's an index on that column. e.g. If col foo has low cardinality, with a bunch of common but a few rare entries, the planner will prefer using the ordering index to the column index even for the very low frequency ones. Partial indexes can be really useful there, as well as order by (id+0). But it's a total hack.