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From Sandeep Joshi <sanjos...@gmail.com>
Subject Question on language translation for Algebricks
Date Sun, 14 Feb 2016 19:02:00 GMT
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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