[jira] Reopened: (LUCENE-773) Deprecate "create" method in FSDirectory.getDirectory in favor of IndexWriter's "create"

["Michael McCandless (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/LUCENE-773?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Michael McCandless reopened LUCENE-773:
---------------------------------------



My fix here broke one case of backwards compatibility for Directory implementations that provide their own locking implementation (ie, that do not use Lockfactory).  See here:

    http://www.gossamer-threads.com/lists/lucene/java-dev/44555

> Deprecate "create" method in FSDirectory.getDirectory in favor of IndexWriter's "create"
> ----------------------------------------------------------------------------------------
>
>                 Key: LUCENE-773
>                 URL: https://issues.apache.org/jira/browse/LUCENE-773
>             Project: Lucene - Java
>          Issue Type: Improvement
>    Affects Versions: 1.9, 2.0.0, 2.0.1, 2.1
>            Reporter: Michael McCandless
>         Assigned To: Michael McCandless
>            Priority: Minor
>             Fix For: 2.1
>
>
> It's confusing that there is a create=true|false at the FSDirectory
> level and then also another create=true|false at the IndexWriter
> level.  Which one should you use when creating an index?
> Our users have been confused by this in the past:
>   http://www.gossamer-threads.com/lists/lucene/java-user/4792
> I think in general we should try to have one obvious way to achieve
> something (like Python: http://en.wikipedia.org/wiki/Python_philosophy).
> And the fact that there are now two code paths that are supposed to do
> the same (similar?) thing, can more easily lead to sneaky bugs.  One
> case of LUCENE-140 (already fixed in trunk but not past releases),
> which inspired this issue, can happen if you send create=false to the
> FSDirectory and create=true to the IndexWriter.
> Finally, as of lockless commits, it is now possible to open an
> existing index for "create" while readers are still using the old
> "point in time" index, on Windows.  (At least one user had tried this
> previously and failed).  To do this, we use the IndexFileDeleter class
> (which retries on failure) and we also look at the segments file to
> determine the next segments_N file to write to.
> With future issues like LUCENE-710 even more "smarts" may be required
> to know what it takes to "create" a new index into an existing
> directory.  Given that we have have quite a few Directory
> implemenations, I think these "smarts" logically should live in
> IndexWriter (not replicated in each Directory implementation), and we
> should leave the Directory as an interface that knows how to make
> changes to some backing store but does not itself try to make any
> changes.

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