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From "Yonik Seeley (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (SOLR-4586) Increase default maxBooleanClauses
Date Thu, 11 Apr 2013 16:43:17 GMT

    [ https://issues.apache.org/jira/browse/SOLR-4586?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13629096#comment-13629096
] 

Yonik Seeley commented on SOLR-4586:
------------------------------------

bq. Sure, just break it up into 1024-term chunks:

Right.  This will be slightly less efficient than one bigger boolean query, but it does work
around the arbitrary limit.  The other workaround is to remove the arbitrary limit ;-)

For those that might not have the historical context: in the past, some auto-expanding term
queries (like fuzzy queries) would generate more and more terms to search until "max clauses"
was hit - so the limit had a purpose.  If you go back far enough, other queries (like prefix
queries) generated unbounded boolean queries, and an exception would be thrown when too many
terms were generated.  The latter was very bad (things worked in production until your index
grew and then would blow up).  Solr luckily never had this issue as it used constant scoring
techniques with no limits for both prefix and range queries from the beginning.

The historical reasons for this limit no longer apply.  No multi-term queries that solr uses
explode into a huge boolean query if you remove the limit (this is what I'm busy verifying
with tests right now).  This only affects explicitly created queries, where it's very bad
to have an artificial limit like this set since it may work in testing and initially in production,
and then blow up in the future because the arbitrary limit was crossed.


                
> Increase default maxBooleanClauses
> ----------------------------------
>
>                 Key: SOLR-4586
>                 URL: https://issues.apache.org/jira/browse/SOLR-4586
>             Project: Solr
>          Issue Type: Improvement
>    Affects Versions: 4.2
>         Environment: 4.3-SNAPSHOT 1456767M - ncindex - 2013-03-15 13:11:50
>            Reporter: Shawn Heisey
>         Attachments: SOLR-4586.patch, SOLR-4586.patch, SOLR-4586.patch, SOLR-4586.patch
>
>
> In the #solr IRC channel, I mentioned the maxBooleanClauses limitation to someone asking
a question about queries.  Mark Miller told me that maxBooleanClauses no longer applies, that
the limitation was removed from Lucene sometime in the 3.x series.  The config still shows
up in the example even in the just-released 4.2.
> Checking through the source code, I found that the config option is parsed and the value
stored in objects, but does not actually seem to be used by anything.  I removed every trace
of it that I could find, and all tests still pass.

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