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Posted to dev@lucene.apache.org by "Michael McCandless (JIRA)" <ji...@apache.org> on 2006/11/30 12:56:22 UTC
[jira] Commented: (LUCENE-735) Simple tool to back-convert from
lockless to pre-lockless file format
[ http://issues.apache.org/jira/browse/LUCENE-735?page=comments#action_12454591 ]
Michael McCandless commented on LUCENE-735:
-------------------------------------------
To use this, apply the patch to the Lucene trunk, then ant jar-core then run this:
java org.apache.lucene.index.ConvertPreLockless <path-to-index>
The conversion is in place, meaning, after this tool runs, your <path-to-index> should be in 2.0 file format.
> Simple tool to back-convert from lockless to pre-lockless file format
> ---------------------------------------------------------------------
>
> Key: LUCENE-735
> URL: http://issues.apache.org/jira/browse/LUCENE-735
> Project: Lucene - Java
> Issue Type: Improvement
> Components: Index
> Affects Versions: 2.1
> Reporter: Michael McCandless
> Assigned To: Michael McCandless
> Priority: Minor
> Fix For: 2.1
>
> Attachments: LUCENE-735.patch
>
>
> Simple tool to back-convert from lockless to pre-lockless file format
> The changes for lockless commits (LUCENE-701 ) are fairly minor and so
> creating a tool to convert a lockless format index back to a
> pre-lockless format index is 1) fairly simple, and 2) useful at least
> for brave souls who want to try lockless but have the freedom to roll
> back to Lucene 2.0, using the same index, if anything goes wrong.
> I will attach an initial patch.
> This has not yet received extensive testing so please be extremely
> careful if you use this in production! I've only done minimal testing
> so far: using IndexFiles to produce an index under lockless,
> converting it to pre-lockless, and then doing searches against that
> index with 2.0. More testing is clearly needed to ensure separate
> deletes, separate norms, etc, are working correctly.
> The tool prints details of what it did, eg:
> >> java org.apache.lucene.index.ConvertPreLockless index
> 3 segments in index
> segment 0: not compound file format
> has deletions
> rename _a_2.del to _a.del
> no separate norms
> segment 1: not compound file format
> has deletions
> rename _b_1.del to _b.del
> no separate norms
> segment 2: not compound file format
> has deletions
> rename _c_1.del to _c.del
> no separate norms
> wrote "segments" file
> rename segments_8 to segments_8.old
> Caveats:
> * Tread very carefully! Test first in a sandox, etc.
> * Make sure you only run this tool on an index that is not in use by
> any reader/writers, else you could have problems: the tool
> currently does not acquire the write lock even though it's
> modifying the index.
> * On Windows only: if your index has any un-referenced files (ie,
> files that should have been deleted but were in use at the time)
> at the time you run this tool, then they will never be deleted
> (ie, pre-lockless Lucene won't know to delete them).
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