> On Dec 5, 2017, at 11:23 PM, Sergei Kornilov <s...@zsrv.org> wrote:
> You has very slow (or busy) disks, not postgresql issue. Reading 6760 * 8KB 
> in 70 seconds is very bad result.
> For better performance you need better disks, at least raid10 (not raid5). 
> Much more memory in shared_buffers can help with read performance and so 
> reduce disk utilization, but write operations still will be slow.
> Sergei


Thanks so much for confirming, this really helps a lot to know what to do. I 
thought the disk could be some of my issue, but I wanted to make sure I did all 
of the obvious tuning first. I have learned some very valuable things which 
I'll be able to use on future challenges like this which I didn't learn 

Based on this advice from everyone, I'm setting up a box with more RAM, lots of 
SSDs, and RAID 10. I'll write back in a few more days after I've completed it.

I can also confirm that the previous advice about using a hash / digest based 
unique index seemed to make the loading process slower for me, not faster, 
which is an interesting result to consider for future users following this 
thread (if any). I don't yet have specific data how much slower, because it's 
actually still going!


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