PM12499: PERFORMANCE ISSUE WHEN USING ID TYPE ELEMENTS WITH SDOS

APAR status

• Closed as program error.

Error description

• A potential performance problem exists in this scenario:
  A large amount of data in a Service Data Object (SDO)  uses the
  following Property type for the configAttribute element:
  
  <xsd:complexType name="Property">
  <xsd:sequence>
  <xsd:element name="name" type="xsd:string" />
  <xsd:element name="value" type="xsd:string" />
  </xsd:sequence>
  </xsd:complexType>
  <xsd:complexType name="someConfig">
  <xsd:sequence>
  <xsd:element name="configAttribute"
  type="tns:Property"
  minOccurs="0" maxOccurs="unbounded" />
  </xsd:sequence>
  </xsd:complexType>
  
  
  The sdo.xml would look like this:
  
  <someConfig>
  <configAttribute>
  <name>some_type</name>
  <value>
  </value>
  </configAttribute>
  <configAttribute>
  <name>some_type_2</name>
  <value>no</value>
  </configAttribute>
  <configAttribute>
  <name>something_enabled</name>
  <value>yes</value>
  </configAttribute>
  <configAttribute>
  <name>some_name</name>
  <value>a_value</value>
  </configAttribute>
  </someConfig>
  
  The SDO contains over 500 of these configAttribute elements.
  
  
  At runtime, it could take about 3-5 ms to get values using an
  XPath expression:
  
  sdo.getString("someConfig/configAttribute[name='some_name
  ']/value")
  
  
  In order to take advantage of the fix in this APAR, it will be
  necessary to change the type of the 'name' element in the
  complexType to be xsd:ID instead of xsd:string:
  
  <xsd:complexType name="Property">
  <xsd:sequence>
  <xsd:element name="name" type="xsd:ID" />
  <xsd:element name="value" type="xsd:string" />
  </xsd:sequence>
  </xsd:complexType>
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:  Users of IBM WebSphere Application Server   *
  *                  7.0 with the Feature Pack for XML 1.0.0.0   *
  *                  or earlier.                                 *
  ****************************************************************
  * PROBLEM DESCRIPTION: Implementation of ID-type navigation    *
  *                      in XCI had functional and performance   *
  *                      issues.                                 *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  The ID-type support in XCI (Object Cache) was causing the
  entire document to be materialized in memory in order to find
  matching nodes.  Furthermore, the ID-type support did not
  provide the correct results when the behaviour requested was the
  XPath/XQuery function "fn:element-with-id()".
  

Problem conclusion

• The ID-type framework in XCI now lazily parses the document
  when searching for the requested ID, and correctly supports the
  "fn:element-with-id()" semantics.
  
  This APAR is currently targeted for inclusion in the Feature
  Pack for XML 1.0.0.7.  Please refer to the Recommended Updates
  page for delivery information:
  http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  XML FEATUREPACK

• Fixed component ID

  5724J0856

Applicable component levels

• R700 PSY

     UP