Re: Better performance no-throw conversion?

On Wed, Sep 8, 2021 at 11:33 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> "ldh(at)laurent-hasson(dot)com" <ldh(at)laurent-hasson(dot)com> writes:
> > Some databases such as SQLServer (try_cast) or BigQuery (safe.cast)
> offer not-throw conversion.
> > ...
> > I couldn't find a reference to such capabilities in Postgres and
> wondered if I missed it, and if not, is there any plan to add such a
> feature?
>
> There is not anybody working on that AFAIK. It seems like it'd have
> to be done on a case-by-case basis, which makes it awfully tedious.
>

Do you just mean a separate function for each data type? I use similar
functions (without a default value though) to ensure that values extracted
from jsonb keys can be used as needed. Sanitizing the data on input is a
long term goal, but not possible immediately.

Is there any documentation on the impact of many many exception blocks?
That is, if such a cast function is used on a dataset of 1 million rows,
what overhead does that exception incur? Is it only when there is an
exception or is it on every row?