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From "Nagendra Nagarajayya (JIRA)" <>
Subject [jira] [Commented] (SOLR-3816) Need a more granular nrt system that is close to a realtime system.
Date Mon, 10 Sep 2012 15:04:07 GMT


Nagendra Nagarajayya commented on SOLR-3816:

The attached patch provides a realtime NRT that is closer to a realtime system and offers
a fine granular NRT, at very high performance and offers a path to a true realtime system
and when the underlying IndexWriter system supports it. A performance of about 70,000 document
adds / sec has been seen on a user system with realtime queries (almost 1.5-2x improvement
over soft-commit)

The realtime nrt can be enabled by adding the following tag to SolrConfig.xml:

<realtime visible="milliseconds">true/false</realtime>

A true enables realtime nrt while false disables it.

The visible attribute controls the time a document may not visible in a search. Settng this
to 0 means new documents are visible immediately in searches. Very High performance can be

observed with visible around 150-200ms.
For eg: <realtime visible="150">true</realtime>

The other parameters supported are:


A true deletes duplicates while a false allows duplicates to exist until a commit. Setting
this to true may impact performance.

The same may be achieved by setting <maxBufferedDeleteTerms> to 1.


1. The cache (Query Result Cache, etc.) needs to be disabled for realtime NRT. 
2. Increase the number of file descriptors to around 64k before starting Solr
	ie. ulimit -n 65536

> Need a more granular nrt system that is close to a realtime system.
> -------------------------------------------------------------------
>                 Key: SOLR-3816
>                 URL:
>             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
> 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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