Re: [HACKERS] TIME QUALIFICATION

> Do you mean subselect.c:147 line:
>
>    slink->subselect = NULL;    /* cool ?! */
>
> ?

    Exactly that!

>
> As I remember this is done to don't copy subquery' Query
> node in copyObject when copying plan. Actually, using
> Query node in Executor is annoying me for ~ 1 year:
> Executor need not in entire Query node, only in range table!
> Using Query in Executor is bad for prepared plans: we do
> copying and storing of mostly useless Query node...
> This would be nice to have some new TopPlan node with
> upmost plan, range table and some other things (I had to
> add some fields to Plan node itself for subqueries while
> these fields should be only in topmost plan node) and get rid
> of using Query in Executor. Query is result of parsing,
> plan is result of planning and source for execution.
>
> If you don't want to implement TopPlan node then you could
> allocate new SubLink node in subselect.c:_make_subplan()
> to be used in node->sublink...

    Ah - I see.

    So  I  assume  the sublink->subselect, that's copied into the
    plan, is totally obsolete too at that point. The subplan  has
    it's  own rangetable, which is the same as the (not used) one
    in the subselect.

    I think I should tidy up that all to finally pass  only  plan
    into  executor  before  going  ahead  with the deferred query
    stuff. It doesn't make sense to  spend  much  efford  now  to
    prepare  the system for deferred queries. It depends too much
    on where the RTE's are and how we organize them.

    New TopPlan could be passed  down  the  executor  instead  of
    querytree.  It  might  hold  a  List of rangetables. Plan and
    SubPlan then have an index telling which nth() rangetable  of
    TopPlan to use for it.

    This  would  make  execution  preprocessing for snapshot->RTE
    assignment very easy because there's only one place  to  find
    ALL  RTE's  (no  need  to traverse down a tree). And it would
    substantial lower the amount of data to copy in SPI, since it
    must not save the Querytree at all.


Jan

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