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From "Michael McCandless (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (LUCENE-4127) negative offsets/deltas corrumption
Date Sun, 10 Jun 2012 14:20:42 GMT

     [ https://issues.apache.org/jira/browse/LUCENE-4127?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Michael McCandless updated LUCENE-4127:
---------------------------------------

    Attachment: LUCENE-4127.patch

I think we should also strongly check posIncr coming into IndexWriter ... attached patch does
that and fixes a couple tests that were sending posInc=0 for first token.
                
> negative offsets/deltas corrumption
> -----------------------------------
>
>                 Key: LUCENE-4127
>                 URL: https://issues.apache.org/jira/browse/LUCENE-4127
>             Project: Lucene - Java
>          Issue Type: Bug
>          Components: core/index
>    Affects Versions: 4.0
>            Reporter: Robert Muir
>         Attachments: LUCENE-4127.patch, LUCENE-4127_test.patch
>
>
> If offsets go negative or backwards, it can corrupt the index with DOCS_AND_FREQS_AND_POSITIONS_AND_OFFSETS:
the offsets will have wrong values (different from the term vectors) or even crazy values
like -2147483645
> The problem with this is that its not just theoretical: its too easy to do this with
lucene's own analyzer chains (e.g. ngramtokenizer).
>  
> See issues such as LUCENE-3920 and some discussion on LUCENE-3738
> The question is how to fix this, e.g. should we:
> # start enforcing that offsets cannot be crazy values in OffsetAttributeImpl/IndexWriter
and fix the broken analyzers
> # leave offsets as a pair of opaque integers, declaring this a limitation of the current
codec, and either workaround or throw UOE from the postings writer.

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