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https://issues.apache.org/jira/browse/LUCENE-1606?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12780654#action_12780654
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Robert Muir commented on LUCENE-1606:
-------------------------------------
OK we have the start of a plan, only one final nit I am worried about.
I pared away the 'built-in named automata':
* example <Lu> (uppercase letter, from Unicode)
* example <QName> (from XML)
if we keep the original pkg name, a user can have these just by adding
brics.jar into their path.
They would just pass new DatatypesAutomatonProvider() to the constructor of
RegexpQuery, done.
if we rename the pkg, this will not work because the DataTypesAutomatonProvider
from the jar file implements dk.brics.automaton.AutomatonProvider,
not o.a.l.util.brics.AutomatonProvider.
alternatively, we could rename the pkg, but I could restore perhaps a subset of
these datatypes, maybe without all the xml ones, just the basic unicode
categories and stuff?
This would cost a little space though. Here is the list:
http://www.brics.dk/automaton/doc/dk/brics/automaton/Datatypes.html#get%28java.lang.String%29
i ask this question because personally i don't use any of these built-ins, but
users might want them? what do you think?
> Automaton Query/Filter (scalable regex)
> ---------------------------------------
>
> Key: LUCENE-1606
> URL: https://issues.apache.org/jira/browse/LUCENE-1606
> Project: Lucene - Java
> Issue Type: New Feature
> Components: contrib/*
> Reporter: Robert Muir
> Assignee: Robert Muir
> Priority: Minor
> Fix For: 3.1
>
> Attachments: automaton.patch, automatonMultiQuery.patch,
> automatonmultiqueryfuzzy.patch, automatonMultiQuerySmart.patch,
> automatonWithWildCard.patch, automatonWithWildCard2.patch, LUCENE-1606.patch,
> LUCENE-1606.patch, LUCENE-1606_nodep.patch
>
>
> Attached is a patch for an AutomatonQuery/Filter (name can change if its not
> suitable).
> Whereas the out-of-box contrib RegexQuery is nice, I have some very large
> indexes (100M+ unique tokens) where queries are quite slow, 2 minutes, etc.
> Additionally all of the existing RegexQuery implementations in Lucene are
> really slow if there is no constant prefix. This implementation does not
> depend upon constant prefix, and runs the same query in 640ms.
> Some use cases I envision:
> 1. lexicography/etc on large text corpora
> 2. looking for things such as urls where the prefix is not constant (http://
> or ftp://)
> The Filter uses the BRICS package (http://www.brics.dk/automaton/) to convert
> regular expressions into a DFA. Then, the filter "enumerates" terms in a
> special way, by using the underlying state machine. Here is my short
> description from the comments:
> The algorithm here is pretty basic. Enumerate terms but instead of a
> binary accept/reject do:
>
> 1. Look at the portion that is OK (did not enter a reject state in the
> DFA)
> 2. Generate the next possible String and seek to that.
> the Query simply wraps the filter with ConstantScoreQuery.
> I did not include the automaton.jar inside the patch but it can be downloaded
> from http://www.brics.dk/automaton/ and is BSD-licensed.
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