Re: Memory allocation error

pá 14. 7. 2023 v 13:13 odesílatel Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> napsal:

> Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> writes:
> > pá 14. 7. 2023 v 9:36 odesílatel Shaozhong SHI <shishaozhong(at)gmail(dot)com>
> > napsal:
> >> On Fri, 14 Jul 2023 at 08:14, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
> >> wrote:
> >>> It depends what you do. Postgres doesn't allow to allocate bigger
> blocks
> >>> than 1GB. Maybe you create too big string or too big value of some
> other
> >>> type. But it can be signal of some cache bloating.
>
> > The best way - do it all in one recursive query without any recursive
> > function.
> > This issue you can fix only by rewriting your code.
>
> Yeah, but nonetheless this error message is pretty user-unfriendly.
>
> The given example is too incomplete to run as-is, but I guessed that
> maybe the array_agg() was accumulating too many values, and sure
> enough it's possible to reproduce:
>
> regression=# select array_agg(x::text) from generate_series(1,100000000) x;
> ERROR: invalid memory alloc request size 1073741824
>
> We can do better than that. The attached patch causes the error to be
>
> regression=# select array_agg(x::text) from generate_series(1,100000000) x;
> ERROR: array size exceeds the maximum allowed (1073741823)
>

+1

it is significantly better

Regards

Pavel

>
> I'm not wedded to that wording, but it's an existing translatable string
> that at least points you in the direction of "my array is too big".
> (This is also what you get if the eventual array construction overruns
> the 1G limit, cf construct_md_array().)
>
> regards, tom lane
>
>