Re: Bug (8.4beta): FailedAssertion("!(bms_is_subset(relids, qualscope))", File: "initsplan.c", Line: 915)

Alvaro Herrera wrote:
> Tom Lane wrote:
>
>> Oh!  What is happening is that to_number(1) is being reduced to constant
>> NULL, whereupon it concludes that ad_tab_id=to_number(1) is constant
>> NULL, ergo the EXISTS can never succeed, ergo the entire WHERE is
>> constant false.
>
>> CREATE FUNCTION to_number(integer) RETURNS numeric
>>     LANGUAGE plpgsql IMMUTABLE
>>     AS $_$
>> BEGIN
>> RETURN to_number($1, 'S99999999999999D999999');
>> EXCEPTION
>>   WHEN OTHERS THEN
>>     RETURN NULL;
>> END;
>> $_$;
>
> How can the executor "see through" a plpgsql function definition?  Or do
> you mean that this reduction is being done at execution time?  (hmm ...
> this is what a one-time filter is, now that I think about it?)

Note that the function is immutable, and the argument in the query is a
constant. The planner simply runs the function and replaces the function
call with the result.

--
   Heikki Linnakangas
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