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https://issues.apache.org/jira/browse/LUCENE-2026?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12789618#action_12789618
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Jake Mannix commented on LUCENE-2026:
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bq. Now we want more speed, and are ready to sacrifice something if needed.
bq. You decide to sacrifice new record (in)visibility. No choice, but to hack
into IW to allow readers see its hot, fresh innards.
Chiming in here that of course, you don't *need* (ie there is a choice) to hack
into the IW to do this. Zoie is a completely user-land solution which modifies
no IW/IR internals and yet achieves millisecond index-to-query-visibility
turnaround while keeping speedy indexing and query performance. It just keeps
the RAMDir outside encapsulated in an object (an IndexingSystem) which has
IndexReaders built off of both the RAMDir and the FSDir, and hides the
implementation details (in fact the IW itself) from the user.
The API for this kind of thing doesn't *have* to be tightly coupled, and I
would agree with you that it shouldn't be.
> 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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