Solr 4.4: StopFilterFactory and enablePositionIncr

问题:

While attempting to upgrade from Solr 4.3.0 to Solr 4.4.0 I ran into this exception:

 java.lang.IllegalArgumentException: enablePositionIncrements=false is not supported anymore as of Lucene 4.4 as it can create broken token streams

which led me to this issue. I need to be able to match queries irrespective of intervening stopwords (which used to work with enablePositionIncrements="true"). For instance: "foo of the bar" would find documents matching "foo bar", "foo of bar", and "foo of the bar". With this option deprecated in 4.4.0 I'm not clear on how to maintain the same functionality.

The package javadoc adds:

If the selected analyzer filters the stop words "is" and "the", then for a document containing the string "blue is the sky", only the tokens "blue", "sky" are indexed, with position("sky") = 3 + position("blue"). Now, a phrase query "blue is the sky" would find that document, because the same analyzer filters the same stop words from that query. But the phrase query "blue sky" would not find that document because the position increment between "blue" and "sky" is only 1.

If this behavior does not fit the application needs, the query parser needs to be configured to not take position increments into account when generating phrase queries.

But there's no mention of how to actually configure the query parser to do this. Does anyone know how to deal with this issue as Solr moves toward 5.0?

回答1:

You can use proximity searching:

"foo bar"~2

回答2:

I don't know if this is recommended for usage, but there are still some legacy classes in Lucene 5, such as Lucene43StopFilter.

Unfortunately they seem to have disappeared in Lucene 6...

回答3:

I found somewhere on the net implementation of RemoveTokenGapsFilterFactory

public final class RemoveTokenGapsFilter extends TokenFilter {

    private final PositionIncrementAttribute posIncrAttribute = addAttribute(PositionIncrementAttribute.class);

    public RemoveTokenGapsFilter(TokenStream input) {
        super(input);
    }

    @Override
    public boolean incrementToken() throws IOException {

        if (input.incrementToken()) {
            posIncrAttribute.setPositionIncrement(1);
            return true;
        }

        return false;
    }
}