Re: BUG #6232: hstore operator ? no longer uses indexes

On ons, 2011-09-28 at 22:42 -0400, Tom Lane wrote:
> "Pierre Ducroquet" <p(dot)psql(at)pinaraf(dot)info> writes:
> > [ the "hstore ? text" operator no longer matches an hstore GIST index ]
>
> Hmm ... this doesn't seem to be specific to either hstore or GIST; it's
> a collation problem. The index is marked as having no collation, which
> is reasonable since hstore is a collation-less type. However, the ?
> OpExpr gets marked as having "default" collation because it has one
> collatable input, namely the text constant. And then,
> match_clause_to_indexcol decides the clause doesn't match the index.
>
> Not sure what to do about this. Is it okay to suppose that collation
> can be ignored when matching to a collation-less index?

That sounds correct on first reading.