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https://issues.apache.org/jira/browse/SOLR-3816?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13494815#comment-13494815
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Yonik Seeley commented on SOLR-3816:
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So I took a quick look at the patch, and it's as I feared from earlier
discussions - the reader is changed out from under the searcher at random
times. This approach simply won't work. Lucene and Solr have searchers that
work on a non-changing reader.
You'll get incorrect documents back, incorrect facets back, pretty much any
number of random looking bugs because internal docids will be changing
underneath you. One only has to look at this snippet of the patch as an
example of an attempt to be defensive about these changing docids:
{code}
+ /* realtime NRT changes */
+ // We may be getting docs that are beyond maxDoc, ignore for this
request.
+ if (doc < maxDoc) {
+ bits.fastSet(doc);
+ }
{code}
So how is it that tests can pass? Well, the vast majority of our tests (like
querying, faceting, etc), index documents and then test the requests. They do
not currently test requests while concurrently indexing (and such tests would
be much more difficult to write of course... one would need to know exactly
what documents made it into the index in order to know what the correct results
should be.
I'm sorry folks, but this really looks like a dead end.
> Need a more granular nrt system that is close to a realtime system.
> -------------------------------------------------------------------
>
> Key: SOLR-3816
> URL: https://issues.apache.org/jira/browse/SOLR-3816
> Project: Solr
> Issue Type: Improvement
> Components: clients - java, replication (java), search,
> SearchComponents - other, SolrCloud, update
> Affects Versions: 4.0
> Reporter: Nagendra Nagarajayya
> Labels: nrt, realtime, replication, search, solrcloud, update
> Attachments: alltests_passed_with_realtime_turnedoff.log,
> SOLR-3816_4.0_branch.patch, SOLR-3816-4.x.trunk.patch,
> solr-3816-realtime_nrt.patch
>
>
> Need a more granular NRT system that is close to a realtime system. A
> realtime system should be able to reflect changes to the index as and when
> docs are added/updated to the index. soft-commit offers NRT and is more
> realtime friendly than hard commit but is limited by the dependency on the
> SolrIndexSearcher being closed and reopened and offers a coarse granular NRT.
> Closing and reopening of the SolrIndexSearcher may impact performance also.
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