Re: BUG #17723: cache lookup failed for type 0

On 12/16/22 18:10, Tom Lane wrote:
> PG Bug reporting form <noreply(at)postgresql(dot)org> writes:
>> This query:
>
>> WITH RECURSIVE
>
>> run(x, y) AS (
>> SELECT 0, 0
>> UNION ALL
>> SELECT x, y FROM run AS r WHERE r.is_cycle
>> )
>> CYCLE x, y SET is_cycle USING path
>
>> TABLE run
>> ;
>
>> in which I mistakenly tried to access the is_cycle column from inside the
>> wle, provokes the following error:
>
>> ERROR: XX000: cache lookup failed for type 0
>> LOCATION: typeOrDomainTypeRelid, parse_type.c:699
>
> Yeah. We are calling addRangeTableEntryForCTE inside parse analysis of
> the CTE's query, and it's generating a ParseNamespaceItem with p_vartype = 0
> because analyzeCTE hasn't yet identified the cycle_mark_type. That
> eventually results in a Var with vartype 0, confusing later parse analysis.
>
> It looks to me like we can just move that part of the code up to before
> we recurse to parse_sub_analyze, though. AFAICS, identification of the
> cycle column type needn't (and had better not) depend on any
> characteristics of the CTE's query.

Indeed, it should only depend on the TO and DEFAULT subclauses (not
shown here).

Thanks for the fix!
--
Vik Fearing