Let's explain little bit better here : First of all, the SynonimFilter is a Token Filter, and being a Token Filter it can be part of an Analysis pipeline at Indexing and Query Time. As the different type of analysis explicitly explains when the filtering happens, let's go to the details of the synonyms.txt. This file contains a set of lines, each of them describing a synonym policy. There are 2 different syntaxes accepted :
*couch,sofa,divanteh => thehuge,ginormous,humungous => largesmall => tiny,teeny,weeny* - A comma-separated list of words. If the token matches any of the words, then all the words in the list are substituted, which will include the original token. - Two comma-separated lists of words with the symbol "=>" between them. If the token matches any word on the left, then the list on the right is substituted. The original token will not be included unless it is also in the list on the right. Related the "expand" param, directly from the official Solr documentation : expand: (optional; default: true) If true, a synonym will be expanded to all equivalent synonyms. If false, all equivalent synonyms will be reduced to the first in the list. So, starting from this definition let's answer to your questions: 1) Related the expand the definition seems quite clear, if anything strange is occurring to you, let me know 2) Related your second question, it depends on your synonym.txt file, if you are not using the => syntax, you are going to always retrieve all the synonyms( included the original term) If you need more info let me know, it can strictly depends how you are using the filter as well ( indexing ? querying ? both ? ) Example : If you are using the filter only at Indexing time, then using the => syntax will prevent the user to search for the original token in the synonym.txt relation. Because it will not appear in the index. Cheers 2015-05-08 9:24 GMT+01:00 Zheng Lin Edwin Yeo <edwinye...@gmail.com>: > Hi, > > Will like to check, for the SynonymFilterFactory, I have the following in > my synonyms.txt: > > Titanium Dioxides, titanium oxide, pigment > pigment, colour, colouring material > > If I set expend=false, and I search for q=pigment, I will get results that > matches pigment, Titanium Dioxides and titanium oxide. But it will not > maches colour and colouring materials, as all equivalent synonyms will only > matches those first in the list. > > If I set expend=false, and I search for q=pigment, I'll get results that > matches everything in the list (ie: Titanium Dioxides, titanium oxide, > colour, colouring material) > > Is my understand correct? > > Also, I will like to check, how come if I search q="pigment" (enclosed in > quotes), I only get matches for Titanium Dioxides and not pigment? > > Regards, > Edwin > -- -------------------------- Benedetti Alessandro Visiting card : http://about.me/alessandro_benedetti "Tyger, tyger burning bright In the forests of the night, What immortal hand or eye Could frame thy fearful symmetry?" William Blake - Songs of Experience -1794 England
