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From Yonik Seeley <>
Subject Re: a bug of solr distributed search
Date Fri, 23 Jul 2010 18:33:22 GMT
On Fri, Jul 23, 2010 at 2:23 PM, MitchK <> wrote:
> why do we do not send the output of TermsComponent of every node in the
> cluster to a Hadoop instance?
> Since TermsComponent does the map-part of the map-reduce concept, Hadoop
> only needs to reduce the stuff. Maybe we even do not need Hadoop for this.
> After reducing, every node in the cluster gets the current values to compute
> the idf.
> We can store this information in a HashMap-based SolrCache (or something
> like that) to provide constant-time access. To keep the values up to date,
> we can repeat that after every x minutes.

There's already a patch in JIRA that does distributed IDF.
Hadoop wouldn't be the right tool for that anyway... it's for batch
oriented systems, not low-latency queries.

> If we got that, it does not care whereas we use doc_X from shard_A or
> shard_B, since they will all have got the same scores.

That only works if the docs are exactly the same - they may not be.


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