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. TheVALUEattribute forAUTO_GENmay be eitherTRUEorFALSE. The default value isTRUE.DEFAULT_SIFT_HIER_DEPTH- Builds a auto-generated sift hierarchy to the depth specified in theVALUEattribute. 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 theLOGto whichMATCHerrors should be written. To avoid duplicate error messages, this is normally a unique log. See theLOGelement'sTYPEattribute 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_GENwithMATCH_EMPTY_PROPSset toTRUE. If this expression node is set toFALSEor 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 theLOGexpression node. Note thatMUST_MATCHshould not be used in combination withAUTO_GEN, because all property values match ifAUTO_GENis specified.REMOVE_PROP- Removes the properties used for theMATCHfrom 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_MATCHis 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_GENmust 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>
