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https://issues.apache.org/jira/browse/SOLR-1321?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12742611#action_12742611
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Robert Muir commented on SOLR-1321:
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btw, i found apache harmony has a nice impl of in-place reversing that is
unicode safe (AbstractStringBuilder.reverse0)
it will treat surrogate pairs as one character for the op just like java 5
StringBuilder.reverse()
since lucene wildcard does not properly handle these, it would probably be bad
to be "unicode correct" at this point.
but perhaps a TODO or comment is desirable, as I hope to improve this situation
in the future!
> Support for efficient leading wildcards search
> ----------------------------------------------
>
> Key: SOLR-1321
> URL: https://issues.apache.org/jira/browse/SOLR-1321
> Project: Solr
> Issue Type: Improvement
> Components: Analysis
> Affects Versions: 1.4
> Reporter: Andrzej Bialecki
> Assignee: Grant Ingersoll
> Fix For: 1.4
>
> Attachments: wildcards-2.patch, wildcards.patch
>
>
> This patch is an implementation of the "reversed tokens" strategy for
> efficient leading wildcards queries.
> ReversedWildcardsTokenFilter reverses tokens and returns both the original
> token (optional) and the reversed token (with positionIncrement == 0).
> Reversed tokens are prepended with a marker character to avoid collisions
> between legitimate tokens and the reversed tokens - e.g. "DNA" would become
> "and", thus colliding with the regular term "and", but with the marker
> character it becomes "\u0001and".
> This TokenFilter can be added to the analyzer chain that it used during
> indexing.
> SolrQueryParser has been modified to detect the presence of such fields in
> the current schema, and treat them in a special way. First, SolrQueryParser
> examines the schema and collects a map of fields where these reversed tokens
> are indexed. If there is at least one such field, it also sets
> QueryParser.setAllowLeadingWildcards(true). When building a wildcard query
> (in getWildcardQuery) the term text may be optionally reversed to put
> wildcards further along the term text. This happens when the field uses the
> reversing filter during indexing (as detected above), AND if the wildcard
> characters are either at 0-th or 1-st position in the term. Otherwise the
> term text is processed as before, i.e. turned into a regular wildcard query.
> Unit tests are provided to test the TokenFilter and the query parsing.
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