Re: FETCH FIRST clause WITH TIES option

As Tom just said in the thread for PERCENT, the gram.y changes need a
better representation.  Also, rename EXACT_NUMBER, per that thread.

As far as I can tell, this concerns feature F867.  I think we should
mark that as supported after this patch -- please edit
src/backend/catalog/sql_features.txt.

Earlier in the thread, Tomas Vondra said:

> 3) I'm a bit confused by the initialization added to ExecInitLimit. It
> first gets the tuple descriptor from the limitstate (it should not do so
                                                                     
 
> directly but use ExecGetResultType). But when it creates the extra slot,
                                                                     
 
> it uses ops extracted from the outer plan. That's strange, I guess ...
                                                                     
 
>
                                                                     
 
> And then it extracts the descriptor from the outer plan and uses it when
                                                                     
 
> calling execTuplesMatchPrepare. But AFAIK it's going to be compared to
                                                                     
 
> the last_slot, which is using a descriptor from the limitstate.
                                                                     
 
>
                                                                     
 
> IMHO all of this should use descriptor/ops from the outer plan, no? It
                                                                     
 
> probably does not change anything because limit does not project, but it
                                                                     
 
> seems confusing.
                                                                     
 

and you replied:

> agree

... yet this doesn't appear to have resulted in any change in the code,
or I just missed it.  Are you going to update the patch per that?

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
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