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From "ASF subversion and git services (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LUCENE-5977) IW should safeguard against token streams returning invalid offsets for multi-valued fields
Date Mon, 29 Sep 2014 15:00:36 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-5977?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14151763#comment-14151763
] 

ASF subversion and git services commented on LUCENE-5977:
---------------------------------------------------------

Commit 1628200 from [~rcmuir] in branch 'dev/branches/lucene_solr_4_10'
[ https://svn.apache.org/r1628200 ]

LUCENE-5977: Fix tokenstream safety checks in IndexWriter to work across multi-valued fields

> IW should safeguard against token streams returning invalid offsets for multi-valued
fields
> -------------------------------------------------------------------------------------------
>
>                 Key: LUCENE-5977
>                 URL: https://issues.apache.org/jira/browse/LUCENE-5977
>             Project: Lucene - Core
>          Issue Type: Bug
>    Affects Versions: 4.9, 4.9.1, 4.10, 4.10.1
>            Reporter: Dawid Weiss
>            Priority: Minor
>             Fix For: 4.10.2
>
>         Attachments: LUCENE-5977.patch
>
>
> We have a custom token stream that emits information about offsets of each token. My
(wrong) assumption was that for multi-valued fields a token stream's offset information is
magically shifted, much like this is the case with positions. It's not the case -- offsets
should be increasing and monotonic across all instances of a field, even if it has custom
token streams. So, something like this:
> {code}
>         doc.add(new Field("field-foo", new CannedTokenStream(token("bar", 1, 150, 160)),
ftype));
>         doc.add(new Field("field-foo", new CannedTokenStream(token("bar", 1,  50,  60)),
ftype));
> {code}
> where the token function is defined as:
> {code}
> token(String image, int positionIncrement, int startOffset, int endOffset)
> {code}
> will result in either a cryptic assertion thrown from IW:
> {code}
> Exception in thread "main" java.lang.AssertionError
> 	at org.apache.lucene.index.FreqProxTermsWriterPerField.writeOffsets(FreqProxTermsWriterPerField.java:99)
> {code}
> or nothing (or a codec error) if run without assertions.
> Obviously returning non-shifted offsets from subsequent token streams makes little sense
but I wonder if it could be made more explicit (or asserted) that offsets need to be increasing
between multiple-values. The minimum is to add some documentation to OffsetAttribute. I don't
know if offsets should be shifted automatically, as it's the case with positions -- this would
change the semantics of existing tokenizers and filters which implement such shifting internally
already.



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