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From Anurag Shekhar <Anurag.Shek...@Sun.COM>
Subject Re: questions about querytreenode and optimization
Date Thu, 12 Jul 2007 13:03:36 GMT
QueryTreeNode is constructed while parsing the sql statement. This is 
the base class of all
the node created while parsing the sql statement. Probably you should 
look at  java/engine/org/apache/derby/impl/sql/compile/sqlgrammar.jj to 
see how three is generated.
You can print the parse tree by turning on debug on "DumpParseTree".

Best place to start on optimization will be the paper on derby optimizer

I am not sure if I have understood the your question about AccessPath can
you please elaborate it ?

Aakash Bordia wrote:
> Hi, I am issuing a simple join query like:
> select * from t1,t2 where t1.c1=t2.c1;
> Here comes my novice questions(bear with me if some of these dont make 
> sense, trying to learn the compiler part):
> 1) I am not sure where to look for the accesspath(both base tables and 
> join),  as the values in AccessPathImpl (at join or PRN or base table 
> level) seem un-intuitive.
> 2) Also it seems we hang the Level2OptimizerImpl objects off of the 
> base table FromBaseTable, but I dont see it up in the tree anywhere. 
> Is there a reason for this?
> Any other pointers for learning about the querytreenodes are appreciated !
> Thanks
> Aakash

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