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
