Hadoop Module

These functions are in the http://xmlns.oracle.com/hadoop/xquery namespace. The oxh prefix is predeclared and the module is automatically imported.

The Hadoop module is described in the following topic:

Hadoop Functions

Built-in Functions for Using Hadoop

The following functions are built in to Oracle XQuery for Hadoop:

oxh:find
oxh:increment-counter
oxh:println
oxh:println-xml
oxh:property

oxh:find

Returns a sequence of file paths that match a pattern.

Signature

oxh:find($pattern as xs:string?) as xs:string*

Parameters

$pattern: The file pattern to search for

oxh:increment-counter

Increments a user-defined MapReduce job counter. The default increment is one (1).

Signature

oxh:increment-counter($groupName as xs:string, $counterName as xs:string, $value as xs:integer

oxh:increment-counter($groupName as xs:string, $counterName as xs:string

Parameters

$groupName: The group of counters that this counter belongs to.

$counterName: The name of a user-defined counter

$value: The amount to increment the counter

oxh:println

Prints a line of text to stdout of the Oracle XQuery for Hadoop client process. Use this function when developing queries.

Signature

declare %updating function oxh:println($arg as xs:anyAtomicType?)

Parameters

$arg: A value to add to the output. A cast operation first converts it to string. An empty sequence is handled the same way as an empty string.

Example

This example prints the values of data.txt to stdout:

for $i in text:collection("data.txt") 
return oxh:println($i)

oxh:println-xml

Prints a line of text or XML to stdout of the Oracle XQuery for Hadoop client process. Use this function when developing queries and printing nodes of an XML document.

Signature

declare %updating function oxh:println-xml($arg as item()?)

Parameters

$arg: A value to add to the output. The input item is converted into a text as defined by XSLT 2.0 and XQuery 1.0 Serialization specifications. An empty sequence is handled the same way as an empty string.

oxh:property

Returns the value of a Hadoop configuration property.

Signature

oxh:property($name as xs:string?) as xs:string?

Parameters

$name: The configuration property