maxMergeDocs in Solr 3.6

["Burton-West, Tom" <tb...@umich.edu>]

Hello all,

I'm getting ready to upgrade from Solr 3.4 to Solr 3.6 and I noticed that maxMergeDocs is no longer in the example solrconfig.xml.
Has maxMergeDocs been deprecated? or doe the tieredMergePolicy ignore it?

Since our Docs are about 800K or more and the setting in the old example solrconfig was 2,147,483,647 we would never hit this limit, but I was wondering about why it is no longer in the example.



Tom

Re: maxMergeDocs in Solr 3.6

[Robert Muir <rc...@gmail.com>]

On Thu, Apr 19, 2012 at 11:54 AM, Burton-West, Tom <tb...@umich.edu> wrote:
> Hello all,
>
> I'm getting ready to upgrade from Solr 3.4 to Solr 3.6 and I noticed that maxMergeDocs is no longer in the example solrconfig.xml.
> Has maxMergeDocs been deprecated? or doe the tieredMergePolicy ignore it?

its not applicable to tieredMergePolicy.

when tieredmergepolicy was added, some previous "global" options were
'interpreted' for backwards compatibility:
useCompoundFile(X) -> setUseCompoundFile(X)
mergeFactor(X) -> setMaxMergeAtOnce(X) AND setSegmentsPerTier(X)

However, in my opinion there is an easier, less confusing, more
systematic approach you can use, and thats to not set these 'global'
params but just specify what you want directly to TieredMergePolicy:

For example for TieredMergePolicy, look at the javadocs of
TieredMergePolicy here:
http://lucene.staging.apache.org/core/3_6_0/api/core/org/apache/lucene/index/TieredMergePolicy.html

you would simply configure it like:

    <mergePolicy class="org.apache.lucene.index.TieredMergePolicy">
      <int name="maxMergeAtOnceExplicit">19</int>
      <int name="segmentsPerTier">9</int>
      <double name="noCFSRatio">1.0</double>
    </mergePolicy>

this will invoke setMaxMergeAtOnceExplicit(19), setSegmentsPerTier(9),
and setNoCFSRatio(1.0). So you can do the same thing with any of those
TieredMergePolicy setters you see in the lucene javadocs.

-- 
lucidimagination.com