Re: hashagg slowdown due to spill changes

Hi,

On June 10, 2020 6:15:39 PM PDT, Jeff Davis <pgsql(at)j-davis(dot)com> wrote:
>On Fri, 2020-06-05 at 21:11 -0700, Andres Freund wrote:
>> Hi,
>>
>> While preparing my pgcon talk I noticed that our hash-agg performance
>> degraded noticeably. Looks to me like it's due to the spilling-
>> hashagg
>> changes.
>
>Attached a proposed fix. (Might require some minor cleanup).
>
>The only awkward part is that LookupTupleHashEntry() needs a new out
>parameter to pass the hash value back to the caller. Ordinarily, the
>caller can get that from the returned entry, but if isnew==NULL, then
>the function might return NULL (and the caller wouldn't have an entry
>from which to read the hash value).

Great!

Did you run any performance tests?

Andres
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