Re: Identity projection

On Saturday, February 09, 2013 9:03 AM Tom Lane wrote:
Amit kapila <amit.kapila@huawei.com> writes:
>>> if (!is_projection_capable_plan(result_plan) && compare_tlist_exprs(sub_tlist, result_plan->targetlist) )

>> Sorry, the check I suggested in last mail should be as below:

>> if (!is_projection_capable_plan(result_plan) && !compare_tlist_exprs(sub_tlist, result_plan->targetlist) )

> You know, I was thinking that compare_tlist_exprs() was a pretty
> unhelpfully-chosen name for a function returning boolean, and this
> thinko pretty much proves the point.  It'd be better to call it
> something like equivalent_tlists(), tlists_are_equivalent(), etc.
> (I'm not caring for the emphasis on the exprs either, because I think
> it'll also be necessary to compare resjunk fields for instance.)

The fields which cannot be compared are resname, resorigtbl, resorigcol as these gets cleared in planner.
I am not sure about fields resno and ressortgroupref, but I will check in more detail before sending patch.


With Regards,
Amit Kapila.