Re: weird hash plan cost, starting with pg10

Alvaro Herrera <alvherre@2ndquadrant.com> writes:
> While messing with EXPLAIN on a query emitted by pg_dump, I noticed that
> current Postgres 10 emits weird bucket/batch/memory values for certain
> hash nodes:

>                          ->  Hash  (cost=0.11..0.11 rows=10 width=12) (actual time=0.002..0.002 rows=1 loops=8)
>                                Buckets: 2139062143  Batches: 2139062143  Memory Usage: 8971876904722400kB
>                                ->  Function Scan on unnest init_1  (cost=0.01..0.11 rows=10 width=12) (actual
time=0.001..0.001rows=1 loops=8) 

Looks suspiciously like uninitialized memory ...

> The complete query is:

Reproduces here, though oddly only a couple of the several hash subplans
are doing that.

I'm not planning to dig into it right this second either.

            regards, tom lane