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https://issues.apache.org/jira/browse/LUCENE-2933?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12997313#comment-12997313
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Simon Willnauer commented on LUCENE-2933:
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bq. I can't assign issues to myself, is that all right?
some jira admin needs to enable this. Grant has JIRA admin rights afaik.

simon

> Two-stage state expansion for the FST: distance-from-root and child-count 
> criteria.
> -----------------------------------------------------------------------------------
>
>                 Key: LUCENE-2933
>                 URL: https://issues.apache.org/jira/browse/LUCENE-2933
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Index
>            Reporter: Dawid Weiss
>            Priority: Trivial
>             Fix For: 4.0
>
>
> In the current implementation FST states are expanded into a binary search on 
> labels (from a vector of transitions) when the child count of a state exceeds 
> a given predefined threshold (NUM_ARCS_FIXED_ARRAY). This threshold affects 
> automaton size and traversal speed (as it turns out when benchmarked). For 
> some degenerate (?) data sets, close-to-the-root nodes could have a small 
> number of children (below the threshold) and yet be traversed on every single 
> seek.
> A fix of this is to introduce two control thresholds: 
>   EXPAND state if (distance-from-root <= MIN_DISTANCE || children-count >= 
> NUM_ARCS_FIXED_ARRAY)
> My plan is to create a data set that will prove this first and then to 
> implement the workaround above.

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