Re: read-only planner input

Neil Conway <neilc@samurai.com> writes:
> I've got most of this finished; I'll post a patch soon. One issue I ran 
> into is how to handle query_tree_mutator() and query_tree_walker(): they 
> both expect to be able to traverse a Query's in_info_list, which my 
> patch moves into the QueryState struct. If maintaining this property is 
> essential, it seems that we'll need a way to get the QueryState 
> associated with a given Query.

whereupon the entire premise of a read-only tree collapses ...

That's a bit nasty.  I'm fairly sure that I added in_info_list to the
walker recursion because I had to; I don't recall the exact scenario,
but I think it needs to be possible to reassign relation numbers
within that data structure if we are doing it elsewhere in a query
tree.
        regards, tom lane