Re: BUG #15320: = any (array(SQL)) ERROR: invalid memory alloc request size 1073741824

Hi,

On 2018-08-10 02:00:56 +0000, PG Bug reporting form wrote:
> postgres=# explain analyze select count(*) from tbl where uid = any
> (array(select uid from tbl limit 100000000)) ;
> ERROR: XX000: invalid memory alloc request size 1073741824
> LOCATION: repalloc, mcxt.c:1050
> Time: 24133.852 ms (00:24.134)
> ```
>
> is it a bug?

No, not in my opinion. You're building a very large array. Arrays are
stored in memory. Allocation sizes in postgres are limited in many
places.

You could argue for removing the limit in this case, but that'd not make
it a bug. And I doubt it's worth changing this. Your array is going to
be huge either way, and we limit arrays (and other datums) to 1GB. We
could fix the growth of the array here to fail a bit later, but that's
it.

Greetings,

Andres Freund