This solution is the easiest of the three synonym choices to implement, but is useful only if you require synonym matching for a maximum of approximately 100 terms. Beyond this limit, query response times experience a growing increase with the number of synonym terms, and it can have a negative impact on indexing performance.
Internal synonyms introduce the concept of expansion level; that is, the conceptual distance between synonyms. A synonym that you specify explicitly has an expansion level of zero. You can then expand the synonyms again, to get further expansions. For example, if there is a hierarchy of synonyms such that terrier expands to dog, and dog expands to animal, then:
terrier to dog has an expansion level of zero.
dog to animal also has an expansion level of zero.
terrier to animal has an expansion level of one.
To use synonyms in an IDOL Server, you must configure the [Synonym] section in the IDOL or Content server configuration file. In this section, you configure a list of synonym jobs, which are run at query time.
Each synonym job defines a file, which has a list of synonyms to process, and the MaxExpandLevel. For example:
[Synonym] 0=PC_Syn [PC_Syn] File=myfile.txt MaxExpandLevel=1
The referenced file must contain comma-separated lists of synonymous terms and phrases for a particular language type. For example, myfile.txt might contain synonyms for animals:
[EnglishUTF8] dog,canine,puppy,hound,wolf cat,feline,kitten,kitty
You must also apply the SynonymType field property to any fields that you want to perform synonym expansion on. For example:
[FieldProcessing] ... 19=SynonymMatch // Specify the fields that synonym expansion will be performed on [SynonymMatch] Property=ApplySynonymMatch PropertyFieldCSVs=*/DRETITLE,*/DRECONTENT // Specify the synonym job to apply to those fields [ApplySynonymMatch] SynonymType=PC_Syn
After synonyms have been activated, you can use them by setting the Synonym action parameter to True in the Query action.
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