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From Mike Carey <dtab...@gmail.com>
Subject Re: Question on language translation for Algebricks
Date Sun, 14 Feb 2016 22:26:30 GMT
Sandeep,

Just to chime in as well:

  - VXQuery is indeed the best example to look at, probably, to 
understand the AsterixDB/Algebricks separation.

  - Hivesterix was built by Yingyi Bu (who'll see this) early on - it 
drove the separation idea, actually, but we made a decision not to try 
and maintain it.  It was intended to provide a third/different proof of 
separation and applicability of the approach, from a research 
standpoint, but doesn't have additional value to offer the world (since 
Hive itself is a moving target and Hive on Tez now provides the 
non-MapReduce-runtime value that Hivesterix initially offered).  Yingi 
would probably be happy to share the code base with you if you wanted to 
look at it for any reason, but the only things in the Apache AsterixDB 
(incubating) project are things deemed worthy of engineering/maintenance 
work.

Hope that helps too!

Cheers,
Mike


On 2/14/16 11:47 AM, Till Westmann wrote:
> Hi Sandeep,
>
> Apache VXQuery, the XQuery implementation mentioned in the SoCC paper, 
> is a separate project [1].
>
> Specifically to your questions:
>
> 1) There is no need to implement other projects that use Algebricks 
> inside of the AsterixDB source tree (as VXQuery shows).
>
> 2) It is clearly easier to combine a Java parser and plan tree 
> generator with Algebricks, but there's no reason why one couldn't 
> connect to other languages (e.g. by using a text-based intermediate 
> format between the parser and the optimizer and between the plan 
> generator and the runtime).
>
> 3) The reason for the different set of rules is that some are language 
> agnostic and some are language-specific. As you can see in figure 2 of 
> the paper a language implementation has to provide language-specific 
> rules to augment the language-agnostic rules provided by Algebricks.
> Specifically, the rules in AsterixDB's asterix-algebra project augment 
> the rules in Algebricks to support AsterixDB's query language AQL.
>
> Hope this helps,
> Till
>
> [1] http://vxquery.apache.org
>
> On 14 Feb 2016, at 11:02, Sandeep Joshi wrote:
>
>> I had some questions about the process of mapping other query 
>> languages to
>> Algebricks.  The Sigmod SoCC 15 paper mentions that two languages XQuery
>> and HiveQL which have been mapped to Algebricks, but the 
>> implementation is
>> not found in either of the two repositories released under Apache.
>>
>> I found Hivesterix and Pregelix under
>> https://github.com/madhusudancs/hyracks/tree/master/fullstack/hivesterix
>>
>> I couldn't find the XQuery to Algebricks translator anywhere. Has this
>> been released ?
>>
>> What is the reason these language translators are not part of the Apache
>> repository ?
>>
>> The Apache repositories contain the language translators for AQL and 
>> SQL.
>> After comparing the implementations for Hivesterix and SQL/AQL, here are
>> some questions
>>
>> 1) Does one have to integrate the parser for a new language within the
>> Apache AsterixDB source tree, or can one build the Algebricks translator
>> outside the Apache tree and invoke the Hyracks job execution engine
>> directly, as is being done in the hivesterix implementation seen here.
>>
>> https://github.com/madhusudancs/hyracks/blob/36bb1021b17b736aa1648bd439e1246ae419aa89/fullstack/hivesterix/hivesterix-dist/src/main/java/edu/uci/ics/hivesterix/runtime/exec/HyracksExecutionEngine.java

>>
>>
>> 2) When a query language is converted to Algebricks, the 
>> ICompilerFactory
>> converts one plan tree to another by calling Visitor::visit() on each 
>> node
>> of the source query.  Does this imply that the plan tree for the source
>> language can only be constructed in Java ?  Would it be
>> difficult/impossible to integrate a parser and plan tree generator which
>> was written in any language into Algebricks ?
>>
>> 3) In the Apache repositories, the query rewrite rules which are used
>> during optimization are found under two different repositories.
>>
>> One in main asterixdb repository
>>
>> https://github.com/apache/incubator-asterixdb/tree/master/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules

>>
>>
>> and the other in the hyracks repository
>>
>> https://github.com/apache/incubator-asterixdb-hyracks/tree/master/algebricks/algebricks-rewriter/src/main/java/org/apache/hyracks/algebricks/rewriter/rules

>>
>>
>> Are these two sets of rules characteristically different or is this
>> duplication just an artifact of rapid prototyping ?
>>
>> Furthermore, none of these rewrite rules seem to be SQL-specific.  Are
>> there any SQL-specific rewrite rules which were added ?
>>
>> -Sandeep


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