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

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.

regards, tom lane