Re: Violation of principle that plan trees are read-only

Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Sun, May 18, 2025 at 7:31 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> While chasing down Valgrind leakage reports, I was disturbed
>> to realize that some of them arise from a case where the
>> executor scribbles on the plan tree it's given, which it is
>> absolutely not supposed to do:

> Is there some way that we can detect violations of this rule
> automatically? I recall that we were recently discussing with Richard
> Guo a proposed patch that would have had a similar problem, so it's
> evidently not that hard for a committer to either fail to understand
> what the rule is or fail to realize that they are violating it.

I proposed a possible way to test for this at [1]. I was intending to
get around to that sooner or later, but the urgency of the matter just
went up in my eyes...

regards, tom lane

[1] https://www.postgresql.org/message-id/flat/2531459.1743871597%40sss.pgh.pa.us