db-derby-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Anurag shekhar <Anurag.Shek...@Sun.COM>
Subject Re: questions about querytreenode and optimization
Date Thu, 12 Jul 2007 15:53:24 GMT
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
>
>


Mime
View raw message