The indexes don't contain visibility information, so Postgres has to look up
the row on disk to verify it isn't dead.
I guess this fact drastically decreases the performance. :-(
The number of rows with a random_number will just grow over time while
the number of questions with status = 1 will always be somewhat constant
at about 10.000 or most likely much less.
I could really use any kind of suggestion on how to improve the query in
order to make it scale better for large data sets The 6-7000 ms for a
clean run is really a showstopper. Need to get it below 70 ms somehow.
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