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https://issues.apache.org/jira/browse/LUCENE-2026?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12789473#action_12789473
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Earwin Burrfoot commented on LUCENE-2026:
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If I understand everything right, with current uberfast reopens (thanks
per-segment search), the only thing that makes index/commit/reopen cycle slow
is the 'sync' call. That sync call on memory-based Directory is noop.
And no, you really should commit() to be able to see stuff on reopen() :) My
god, seeing changes that aren't yet commited - that violates the meaning of
'commit'.
The original purporse of current NRT code was.. well.. let me remember.. NRT
search! :) With per-segment caches and sync lag defeated you get the delay
between doc being indexed and becoming searchable under tens of milliseconds.
Is that not NRT enough to introduce tight coupling between classes that have
absolutely no other reason to be coupled??
Lucene 4.0. Simplicity is our candidate! Vote for Simplicity!
*: Okay, there remains an issue of merges that piggyback on commits, so writing
and commiting one smallish segment suddenly becomes a time-consuming operation.
But that's a completely separate issue. Go, fix your mergepolicies and have a
thread that merges asynchronously.
> Refactoring of IndexWriter
> --------------------------
>
> Key: LUCENE-2026
> URL: https://issues.apache.org/jira/browse/LUCENE-2026
> Project: Lucene - Java
> Issue Type: Improvement
> Components: Index
> Reporter: Michael Busch
> Assignee: Michael Busch
> Priority: Minor
> Fix For: 3.1
>
>
> I've been thinking for a while about refactoring the IndexWriter into
> two main components.
> One could be called a SegmentWriter and as the
> name says its job would be to write one particular index segment. The
> default one just as today will provide methods to add documents and
> flushes when its buffer is full.
> Other SegmentWriter implementations would do things like e.g. appending or
> copying external segments [what addIndexes*() currently does].
> The second component's job would it be to manage writing the segments
> file and merging/deleting segments. It would know about
> DeletionPolicy, MergePolicy and MergeScheduler. Ideally it would
> provide hooks that allow users to manage external data structures and
> keep them in sync with Lucene's data during segment merges.
> API wise there are things we have to figure out, such as where the
> updateDocument() method would fit in, because its deletion part
> affects all segments, whereas the new document is only being added to
> the new segment.
> Of course these should be lower level APIs for things like parallel
> indexing and related use cases. That's why we should still provide
> easy to use APIs like today for people who don't need to care about
> per-segment ops during indexing. So the current IndexWriter could
> probably keeps most of its APIs and delegate to the new classes.
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