Re: PG optimization question

maybe that 'one big table' needs something called 'normalisation'
first. See how much that will shed off. You might be surprised.
The partitioning needs to be done by some constant intervals, of time
- in your case. Whatever suits you, I would suggest to use the rate
that will give you both ease of archiving/removal of old data (so not
too wide), and also, one that would make sure that most of the data
you'll be searching for in your queries will be in one , two
partitions per query.