DVAL
expressions return dimension values.
Although the
DVAL MATCH
expression is not deprecated, we strongly
recommend that you use the
PROP_MAPPER
element to perform property and dimension
value mapping operations.
The
DVAL MATCH
expression is used to perform text matching
within one or more dimensions. The dimensions are specified in
DIMENSION_ID EXPRNODE
elements. Specify the values to
match in one or more
PROPERTY
expressions. The expression returns a set of
matching dimension values. This is useful within a
VOID ADD_DVAL
expression that contains
PROPERTY IDENTITY
sub-expressions, to assign the
dimension values matching each record’s property values to the record.
You can adjust the behavior of the
DVAL MATCH
expression by nesting
EXPRNODE
elements within the
DVAL MATCH
expression. The nested expression node has
a
NAME
attribute that specifies how to adjust the
behavior.
The following list provides the supported values of the NAME attribute
and describes their effects on the behavior of
DVAL MATCH
.
AUTO_GEN
- Causes new dimension values to be generated automatically to match property values that do not already match dimension values within the dimension. TheVALUE
attribute forAUTO_GEN
may be eitherTRUE
orFALSE
. The default value isTRUE
.DEFAULT_SIFT_HIER_DEPTH
- Builds a auto-generated sift hierarchy to the depth specified in theVALUE
attribute. For example,<EXPRNODE NAME="DEFAULT_SIFT_HIER_DEPTH" VALUE="2"/>
builds to a depth of two. See "Working with Large Dimension Hierarchies" in the Developer Studio Help for details.LOG
- Identifies theLOG
to whichMATCH
errors should be written. To avoid duplicate error messages, this is normally a unique log. See theLOG
element'sTYPE
attribute to specify unique error message logging.MATCH_EMPTY_PROPS
- Specifies that Forge create an empty dimension value for any empty property value Forge finds during matching. This empty property to dimension value matching occurs when you useAUTO_GEN
withMATCH_EMPTY_PROPS
set toTRUE
. If this expression node is set toFALSE
or omitted, Forge ignores empty properties.MUST_MATCH
- Specifies that every property value must match a dimension value within the specified dimensions. If a property value does not have a match, an error is written out to the log named in theLOG
expression node. Note thatMUST_MATCH
should not be used in combination withAUTO_GEN
, because all property values match ifAUTO_GEN
is specified.REMOVE_PROP
- Removes the properties used for theMATCH
from the current record after the match is performed. This is useful if the dimension is being indexed, but not the source property.SIFT_MATCH
-SIFT_MATCH
is a special variation ofAUTO_GEN
. See the MDEX Engine Development Guide for details.SYN_MATCH
- Uses the name of the first property value that matches a dimension value as the synonym name for any property values that do not match to a dimension value. The Forge matching process goes as follows: First,AUTO_GEN
must set beFALSE
. During matching, if more than one property value matches a dimension value, Forge logs an error. If a property value does not match a dimension value, Forge creates a new dimension value using the property value as its name. All the non-matching property values are turned into synonyms of this dimension value.
See the
EXPRESSION
element for DTD and attribute information.
This example assigns the dimension value 2090 to records with the property name FORMAT.
<EXPRESSION TYPE="VOID" NAME="ADD_DVAL"> <EXPRESSION TYPE="DVAL" NAME="MATCH"> <EXPRNODE NAME="DIMENSION_ID" VALUE="2090"/> <EXPRESSION TYPE="PROPERTY" NAME="IDENTITY"> <EXPRNODE NAME="PROP_NAME" VALUE="FORMAT"/> <EXPRNODE NAME="LOG" VALUE="salog"/> </EXPRESSION> </EXPRESSION> </EXPRESSION>