Re: BUG #14932: SELECT DISTINCT val FROM table gets stuck in an infinite loop

On 01/29/18 14:26, Andres Freund wrote:
> On 2018-01-29 13:56:37 -0500, Todd A. Cook wrote:
>> With those patches applied, I'm able to process a 175 million row data set
>> without any problems.
> 
> Cool!
> 
>> I'll try the 900 million row set next.

We're also able to process those 900 million rows without problems. :)
It took about 28 minutes (average of 3 runs).

Out of curiosity, I then modified hashint8() as previously described.
With that change, run time dropped to 11 minutes (also average of 3
runs).

FWIW, the data values in these sets are sort-of random (where I can't
explain the "sort-of" in a public forum), but strongly biased towards
negative infinity.  Starting again from scratch, we could probably remove
the bias, but we have 28-30 billion of these things collected over the
last 14 years (starting in PostgreSQL 7.4) and it's kinda tough to change
directions at this point...

-- todd