On 6/19/2011 7:32 AM, Michael McCandless wrote:
With LogXMergePolicy (the default before 3.2), optimize respects
mergeFactor, so it's doing 2 steps because you have 37 segments but 35
mergeFactor.
With TieredMergePolicy (default on 3.2 and after), there is now a
separate merge factor used for optimize (maxMergeAtOnceExplicit)... so
you could eg set this factor higher and more often get a single merge
for the optimize.
This makes sense. the default for maxMergeAtOnceExplicit is 30
according to LUCENE-854, so it merges the first 30 segments, then it
goes back and merges the new one plus the other 7 that remain. To
counteract this behavior, I've put this in my solrconfig.xml, to test
next week.
<mergePolicy class="org.apache.lucene.index.TieredMergePolicy">
<int name="maxMergeAtOnceExplicit">70</int>
</mergePolicy>
I figure that twice the megeFactor (35) will likely cover every possible
outcome. Is that a correct thought?
Thanks,
Shawn
