After determining the best path (based on cost) a java class is
generated for the query. You can dump this class file on by setting
DumpClassFile to true.
anurag
Aakash Bordia wrote:
> Thanks Anurag, I did look at the documentation and the debug property
> you mentioned. I wanted to mention that I am in the debugger, and
> whatever I asked was in context of that (that is while debugging the
> code, I am not sure where to find the access path in the QTN once the
> optimize method is done with. Same for the second question).
>
> Thanks
> Aakash
>
>
> On 7/12/07, *Anurag Shekhar* <Anurag.Shekhar@sun.com
> <mailto:Anurag.Shekhar@sun.com>> wrote:
>
> 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
> http://db.apache.org/derby/papers/optimizer.html
>
> I am not sure if I have understood the your question about
> AccessPath can
> you please elaborate it ?
> anurag
>
> 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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