Re: Get access to the whole query in CustomScan path callback

Amin <amin(dot)fallahi(at)gmail(dot)com> writes:
> The goal is to have access to all the tables that are being scanned or will
> be scanned as a part of the query. Basically, the callback looks like this:

> typedef void (*set_rel_pathlist_hook_type) (PlannerInfo *root,
> RelOptInfo *rel,
> Index rti,
> RangeTblEntry *rte);

> Now, the problem is when there is a nested query, the function will be
> called once for the parent query and once for the subquery. However, I need
> access to the whole query in this function. There seems to be no CustomScan
> callback before this that has the whole query passed to it. Is there any
> way I can get access to the complete query (or all the relations in the
> query) by using the parameters passed to this function? Or any other
> workaround?

Everything the planner knows is accessible via the "root" pointer.

I very strongly question the idea that a custom scan provider should
be doing what you say you want to do, but the info is there.

regards, tom lane