Re: [bug?] Missed parallel safety checks, and wrong parallel safety

Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> writes:
> On Wed, Apr 21, 2021 at 8:12 AM tsunakawa(dot)takay(at)fujitsu(dot)com
> <tsunakawa(dot)takay(at)fujitsu(dot)com> wrote:
>> From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
>>> [ raised eyebrow... ] I find it very hard to understand why that would
>>> be necessary, or even a good idea.

> IIUC, the idea here is to check for parallel safety of functions at
> someplace in the code during function invocation so that if we execute
> any parallel unsafe/restricted function via parallel worker then we
> error out. If so, isn't it possible to deal with built-in and
> non-built-in functions in the same way?

Yeah, one of the reasons I doubt this is a great idea is that you'd
still have to fetch the pg_proc row for non-built-in functions.

The obvious place to install such a check is fmgr_info(), which is
fetching said row anyway for other purposes, so it's really hard to
see how adding anything to FmgrBuiltin is going to help.

regards, tom lane