Re: Common Table Expressions applied; some issues remain

On Oct 5, 2008, at 1:11 AM, Peter Eisentraut wrote:
> I don't think we should overload syntax choices with optimization  
> hints.   We don't really know why or how people will be using this  
> syntax, and labeling it from the start as "will have unusual  
> performance behavior" isn't a good sell.
>
> As a precedent, consider the JOIN syntax, which is obviously  
> redundant and in its first implementation contained an implicit  
> optimization hint with regard to join order that later had to be  
> done away with because it confused users (I think).  The CTE case  
> is quite similar, and maybe the GUC answer of old could apply here  
> as well.  But I think by default we should abide by SQL's  
> declarative approach of "Tell me what you want and I'll execute it  
> any way I like."


Agreed. It's already horrible that we suggest people use OFFSET 0,  
only because we don't want to define formal optimizer hints (and  
that's *exactly* what OFFSET 0 is).
-- 
Decibel!, aka Jim C. Nasby, Database Architect  decibel@decibel.org
Give your computer some brain candy! www.distributed.net Team #1828