Re: EXPLAIN, utility statement parameters, and recent plpgsql changes

Dimitri Fontaine <dfontaine(at)hi-media(dot)com> writes:
> Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
>> This works well enough for regular DML statements, but it falls down for
>> EXPLAIN which is a utility statement, because *parse analysis of utility
>> statements doesn't do anything*. EXPLAIN actually does the parse
>> analysis of its contained statement at the beginning of execution.
>> And that is too late, in the scenario Pavel exhibited. Why is it too
>> late? Because SPI_cursor_open_internal() intentionally "freezes" the
>> ParamListInfo struct after doing initial parsing: what it copies into
>> the cursor portal is just a static list of data values without the
>> parser hooks (see copyParamList).

> Would it make any sense for this function to get to call the hook in the
> case a utility statement is being processed?

Well, the point of the hook is to change the results of parse
transformation, so just calling it doesn't do much --- you have to apply
the whole parse analysis process, *and keep the resulting tree*.

regards, tom lane