[jira] [Commented] (LUCENE-10010) Should we have a NFA Query?

["Dawid Weiss (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/LUCENE-10010?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17367020#comment-17367020 ] 

Dawid Weiss commented on LUCENE-10010:
--------------------------------------

I think it makes sense. Russ's article is a wonderful writeup on not just regexp-automata but on automata in general (there are three parts if I recall right). NFA traversal is not necessarily slow - tracking multiple paths can slow it down a bit but typically it's still fast.

> Should we have a NFA Query?
> ---------------------------
>
>                 Key: LUCENE-10010
>                 URL: https://issues.apache.org/jira/browse/LUCENE-10010
>             Project: Lucene - Core
>          Issue Type: New Feature
>          Components: core/search
>    Affects Versions: main (9.0)
>            Reporter: Haoyu Zhai
>            Priority: Major
>
> Today when a {{RegexpQuery}} is created, it will be translated to NFA, determinized to DFA and eventually become an {{AutomatonQuery}}, which is very fast. However, not every NFA could be determinized to DFA easily, the example given in LUCENE-9981 showed how easy could a short regexp break the determinize process.
> Maybe, instead of marking those kind of queries as adversarial cases, we could make a new kind of NFA query, which execute directly on NFA and thus no need to worry about determinize process or determinized DFA size. It should be slower, but also makes those adversarial cases doable.
> [This article|https://swtch.com/~rsc/regexp/regexp1.html] has provided a simple but efficient way of searching over NFA, essentially it is a partial determinize process that only determinize the necessary part of DFA. Maybe we could give it a try?



--
This message was sent by Atlassian Jira
(v8.3.4#803005)

---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscribe@lucene.apache.org
For additional commands, e-mail: issues-help@lucene.apache.org