Re: pgsql: Add GET DIAGNOSTICS ... PG_CONTEXT in PL/PgSQL

Stephen Frost <sfrost@snowman.net> writes:
> That said, I'll work on making this more independent of the error handling
> and see if it can be made to use an independent memory context and try to
> tighten it up to ensure it isn't called in an error case.  Future callers
> may try to.

I'm not following your reasoning here.  This *has* to be called in an
error case, before you're outside the error processing context.
Otherwise there would be no data available to be printed.

In short: FlushErrorState, by definition, destroys the information that
GetErrorContextStack looks at.  So in the current implementation,
GetErrorContextStack is burning its bridges behind it.  That's at the
very least a surprising behavior.  I am betting that it will have
unpleasant consequences for any sort of nested-error scenario.

            regards, tom lane