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From Haisheng Yuan <>
Subject Re: Question of Calcite Dynamic Code Generation Feature
Date Wed, 13 May 2020 19:47:26 GMT
The generated code is readable and debuggable.
The more data you have, the more benefits you get from Codegen.

On 2020/05/13 19:19:13, Rui Wang <> wrote: 
> Based on my past experience in distributed computing, there is a difference
> between a compilation time that generates java code and then compiles java
> code into bytecode, and a runtime that runs bytecode by JVM.
> The compilation will take time, but the runtime shouldn't be slower due to
> a good generation of bytecode. It works for distributed computation. For
> example, the query complies in your local machine, slower compilation time
> (a few more minutes?) is ok, and then the bytecode will run on multiple
> workers which can execute bytecode directly (so efficient). I don't have a
> benchmark to show the difference between running java code and executing
> bytecode, but in Apache Beam, after we switched to the dynamic code
> generation, we didn't see a performance regression.
> However I don't have enough experience on if single machine SQL engine can
> benefit from this concept.
> -Rui
> On Wed, May 13, 2020 at 11:54 AM 徐泷泽 <> wrote:
> > Hi buddies !
> > Our team is working on developing a  mulit data source sql engine use
> > Calcite.But something confuse us,  why calcite generate Java code
> > dynamicly on SQL query, it seen have performance issues in my opinion.
> > And building dynamic code object is very hard,the code is unreadable and
> > hard to understood, futhermore we can not debug it.
> >
> >
> > i wander why it was designed like that, what advantage  of that .we
> > search on internet, 
> > but nobody can realy explain it(may be we not goot at search, and poor
> > english).
> > so anybody can tell me the history of this, or give us some article.
> >
> >
> > applogize for my poor english,  hope you know what i'm taking aboult.
> > thank you very very very much !

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