ok, I just avoided it using sum(cnt::int) since cnt is small.
2017-11-15 00:25, Tom Lane:
> Dingyuan Wang <gumblex(at)aosc(dot)io> writes:
>> PostgreSQL 10.0 on x86_64-pc-linux-gnu, compiled by gcc (Debian 7.2.0-8)
>> 7.2.0, 64-bit
>>
>> (gdb) bt
>> #0 int8_avg_combine (fcinfo=0x55bdb92472d8) at
>> ./build/../src/backend/utils/adt/numeric.c:4285
>
> I think this is the same issue being discussed at
>
> https://www.postgresql.org/message-id/flat/20171110185747.31519.28038%40wrigleys.postgresql.org
>
> regards, tom lane
>
>