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From "Preston Carman (JIRA)" <>
Subject [jira] [Assigned] (VXQUERY-31) Complete the implementation of XQuery Functions and Operators
Date Wed, 12 Sep 2012 23:54:09 GMT


Preston Carman reassigned VXQUERY-31:

    Assignee: Preston Carman
> Complete the implementation of XQuery Functions and Operators
> -------------------------------------------------------------
>                 Key: VXQUERY-31
>                 URL:
>             Project: VXQuery
>          Issue Type: Improvement
>            Reporter: Vinayak Borkar
>            Assignee: Preston Carman
>              Labels: gsoc, gsoc2012, mentor
> VXQuery is an XQuery compiler and runtime being built to comply with version 1.0 of the
XQuery spec at The distinguishing characteristic of this runtime
is that it is designed to evaluate queries on large amounts of XML data. VXQuery uses the
Hyracks platform (, a parallel dataflow engine, to parallelize
queries so they can run on a cluster of shared-nothing computers.
> We plan to exploit three kinds of parallelism within the XQuery engine while evaluating
a single query.
> 1. Independent parallelism: Parts of a query that are unrelated to each other can be
evaluated in parallel.
> 2. Partitioned parallelism: The engine partitions data (both input data as well as intermediate
data) and processes the partitions in parallel.
> 3. Pipelined parallelism: The runtime organizes the work done to evaluate a query as
a sequence of workers. As and when work is completed on a piece of data, the results of that
piece are handed to the next worker, while the first can process the next piece of data. This
is similar to an assembly line used in manufacturing plants.
> Hyracks provides a set of operators to be able to evaluate queries in parallel. However,
it does not know anything about VXQuery or the XQuery language and datamodel.
> Currently we have a parser and translator that converts XQuery into a logical form ready
for evaluation.
> The task that needs to be done as part of this project is to implement functions that
will plug into Hyracks operators so we can evaluate XQuery queries.

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