Tom Lane mentioned :
=> Not if you haven't got the RAM to support it :-(
=>
=> Another thing you might look at is ANALYZEing the tables again after
=> you've loaded all the new data. The row-count estimates seem way off
=> in these plans. You might need to increase the statistics target,
=> too, to get better plans.
Thanks Tom, Christopher and Magnus!
I tested this, and found the correct sort_mem setting for my situation.
I'm testing a new default_statistics_target setting.
This is something I never considered.
Kind Regards
Stefan