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From "Shai Erera (JIRA)" <>
Subject [jira] Commented: (LUCENE-2386) IndexWriter commits unnecessarily on fresh Directory
Date Mon, 12 Apr 2010 09:09:40 GMT


Shai Erera commented on LUCENE-2386:

bq. what is the proper way (after this fix) to open an IR over possibly-empty directory? 

You can simply call commit() immediately after you open IW. If that's what you need then it
will work for you.

You're right that if I add docs, deletes and them commits, I'll get an empty segment. So is
if you do "new IW()" and then "iw.close()" w/ no addDocument in between. The point here was
that we should not create a commit unless the user has specifically asked for it. Calling
close() means asking for a commit, per close semantics and contract. But if the app called
new IW, add docs and crashed in the middle, the Directory will still remain empty ... which
is sort of what, IMO, should happen.

I agree it's a matter of perspective. I think that when autoCommit was removed, so should
have been this code. I don't know if it was left behind for a good reason, or simply because
when someone tried to do it, he found out it's not that simple (like I have :)).

> IndexWriter commits unnecessarily on fresh Directory
> ----------------------------------------------------
>                 Key: LUCENE-2386
>                 URL:
>             Project: Lucene - Java
>          Issue Type: Bug
>          Components: Index
>            Reporter: Shai Erera
>            Assignee: Shai Erera
>             Fix For: 3.1
>         Attachments: LUCENE-2386.patch, LUCENE-2386.patch, LUCENE-2386.patch, LUCENE-2386.patch,
> I've noticed IndexWriter's ctor commits a first commit (empty one) if a fresh Directory
is passed, w/ OpenMode.CREATE or CREATE_OR_APPEND. This seems unnecessarily, and kind of brings
back an autoCommit mode, in a strange way ... why do we need that commit? Do we really expect
people to open an IndexReader on an empty Directory which they just passed to an IW w/ create=true?
If they want, they can simply call commit() right away on the IW they created.
> I ran into this when writing a test which committed N times, then compared the number
of commits (via IndexReader.listCommits) and was surprised to see N+1 commits.
> Tried to change doCommit to false in IW ctor, but it got IndexFileDeleter jumping on
me .. so the change might not be that simple. But I think it's manageable, so I'll try to
attack it (and IFD specifically !) back :).

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