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From "Tim Smith (JIRA)" <j...@apache.org>
Subject [jira] [Reopened] (LUCENE-4557) Indexed Offsets Can Be Lost During Merge
Date Wed, 14 Nov 2012 15:36:12 GMT

     [ https://issues.apache.org/jira/browse/LUCENE-4557?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Tim Smith reopened LUCENE-4557:
-------------------------------


I disagree with that assessment

the problem here is not that offsets are not available on "old docs" 

the problem is that offsets are destroyed on documents that had them set properly. This is
very much a bug.
a small temporary config mistake by a user can cause destruction of indexed data during merging.
even after corrected.

As far as i'm concerned, this issue makes it unfeasible to ever use indexed offsets even though
i very much want to.

reindexing data is quite often out of the question when large indexes are involved.






                
> Indexed Offsets Can Be Lost During Merge
> ----------------------------------------
>
>                 Key: LUCENE-4557
>                 URL: https://issues.apache.org/jira/browse/LUCENE-4557
>             Project: Lucene - Core
>          Issue Type: Bug
>    Affects Versions: 4.0
>            Reporter: Tim Smith
>         Attachments: OffsetsTest.java
>
>
> Primary Use case:
> Start with pre-4.0 index (no indexed offsets available)
> Start indexing new documents with indexed offsets (IndexOptions.DOCS_AND_FREQS_AND_POSITIONS_AND_OFFSETS,
previously was IndexOptions.DOCS_AND_FREQS_AND_POSITIONS)
> merge/optimize index
> newly indexed documents will now no longer have offsets available
> In general, it is impossible to ever change a field to have offsets indexed when starting
with an existing index as a merge will cause offsets to be removed from the index.
> Desirable behavior would be for new documents to have offsets indexed properly, and old
documents would have offset of "0, 0" for all positions after merging with a segment that
contains offsets
> Current behavior can be very dangerous.
> for example:
> * Start indexing documents with indexed offsets
> * change config to not index offsets by accident
> * index 1 document
> * revert config back
> * offsets will start disappearing from documents as segments are merged

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