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https://issues.apache.org/jira/browse/DIRSERVER-1642?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13086861#comment-13086861
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Emmanuel Lecharny commented on DIRSERVER-1642:
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I think it's a bit more complex than just using the Key in the Browser. IMO,
the remove (or add) operation must update the browser so that the call to a
getNextTuple or getPreviousTuple still return the correct value. One idea would
be to retain the last returned key, so that we can reinitialize the index.
There is a corner case though for a delete : if the removed element is the last
returned one, we must have a way to set the correct position by using the key
we returned two calls before.
And i'm afraid it's not enough : for big indexes, the BTree will be span on
multiple BPage, and during the remove operation, we don't have access to the
browser.
Removing an element in a BTree while browsing it seems a bad idea...
Otherwise, the ultimate solution is to drop JDBM and to use a MVCC system,
where elements are not deleted when in use. But this is another story...
> Unexpected behaviour in JdbmIndex
> ---------------------------------
>
> Key: DIRSERVER-1642
> URL: https://issues.apache.org/jira/browse/DIRSERVER-1642
> Project: Directory ApacheDS
> Issue Type: Bug
> Reporter: Stefan Seelmann
> Attachments: IndexTest.java
>
>
> During my experiments and tests of removing one-level and sub-level indices
> at least one integration test "SearchAuthorizationIT" failed (the test fails
> recursivelyDelete()). A debugging session showed that the follwing:
> - in recursivelyDelete() multiple search requests are done which leads to
> multiple open cursors in the XDBM search engine
> - an entry is deleted
> - when the open cursors are advanced wrong/unexpected entries are returned
> I was able to create a small test that shows the problem:
> - the index contains six tuples:
> (a,1)
> (b,2)
> (c,3)
> (d,4)
> (e,5)
> (f,6)
> - a cursor over the index is created and advanced two times, the expected
> tuples (a,1) and (b,2) were returned
> - now tuple (c,3) is deleted
> - when the cursor is advanced again the tuple (b,2) is returned again! I had
> expected (d,4).
> Note that this doesn't happen with AvlIndex.
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