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https://issues.apache.org/jira/browse/OAK-5212?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15721960#comment-15721960
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Chetan Mehrotra commented on OAK-5212:
--------------------------------------
Thought about using that but the javadocs indicated that it may result in false
positive
{noformat}
/**
* Returns true if this index has deletions (including
* buffered deletions). Note that this will return true
* if there are buffered Term/Query deletions, even if it
* turns out those buffered deletions don't match any
* documents.
*/
public synchronized boolean hasDeletions() {
{noformat}
Per javadoc this means that it can have false positive and that too for delete
which is the case we addressing via this issue
{noformat}
/** Returns true if there may be changes that have not been
* committed. There are cases where this may return true
* when there are no actual "real" changes to the index,
* for example if you've deleted by Term or Query but
* that Term or Query does not match any documents.
* Also, if a merge kicked off as a result of flushing a
* new segment during {@link #commit}, or a concurrent
* merged finished, this method may return true right
* after you had just called {@link #commit}. */
public final boolean hasUncommittedChanges() {
{noformat}
It would have been simpler if {{IndexWriter}} could have returned a boolean
flag indicating that it actually wrote something
> Avoid updating the index nodestate if no change is done in index
> ----------------------------------------------------------------
>
> Key: OAK-5212
> URL: https://issues.apache.org/jira/browse/OAK-5212
> Project: Jackrabbit Oak
> Issue Type: Improvement
> Components: lucene
> Reporter: Chetan Mehrotra
> Assignee: Chetan Mehrotra
> Priority: Minor
> Labels: performance
> Fix For: 1.6
>
> Attachments: OAK-5212-v1.patch
>
>
> As noted in OAK-5211 directory listing was getting modified (due to reorder)
> even if no change happens in index.
> Another place where we update state post index close is at ":status" node
> where we store {{lastUpdated}} and {{indexedNodes}} post index close. In
> normal cases LuceneIndexEditor avoids initializing the IndexWriter if there
> is no change. However it can happen that when any node gets deleted the
> editor performs a delete operation. It can happen that tree being deleted is
> not indexed but still editor would do this as it cannot determine that
> easily. And in doing that IndexWriter would be initialized.
> Currently IndexWriter being initialized is considered same as index updated.
> Due to this index status nodes gets unnecessarily updated even if there is no
> change in index which causes the IndexTracker to reopen the index even when
> it has not changed.
> We should make this more explicit and find a way to determine if index has
> been updated or not
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