>From the Lucene MergePolicy Javadoc: "Whenever the segments in an index have been altered by IndexWriter <https://lucene.apache.org/core/5_4_0/core/org/apache/lucene/index/IndexWriter.html>, either the addition of a newly flushed segment, addition of many segments from addIndexes* calls, or a previous merge that may now need to cascade, IndexWriter <https://lucene.apache.org/core/5_4_0/core/org/apache/lucene/index/IndexWriter.html> invokes findMerges(org.apache.lucene.index.MergeTrigger, org.apache.lucene.index.SegmentInfos, org.apache.lucene.index.IndexWriter) <https://lucene.apache.org/core/5_4_0/core/org/apache/lucene/index/MergePolicy.html#findMerges(org.apache.lucene.index.MergeTrigger, org.apache.lucene.index.SegmentInfos, org.apache.lucene.index.IndexWriter)> to give the MergePolicy a chance to pick merges that are now required. This method returns a MergePolicy.MergeSpecification <https://lucene.apache.org/core/5_4_0/core/org/apache/lucene/index/MergePolicy.MergeSpecification.html> instance describing the set of merges that should be done, or null if no merges are necessary. When IndexWriter.forceMerge is called, it calls findForcedMerges(SegmentInfos,int,Map, IndexWriter) <https://lucene.apache.org/core/5_4_0/core/org/apache/lucene/index/MergePolicy.html#findForcedMerges(org.apache.lucene.index.SegmentInfos, int, java.util.Map, org.apache.lucene.index.IndexWriter)> and the MergePolicy should then return the necessary merges."
See: https://lucene.apache.org/core/5_4_0/core/org/apache/lucene/index/MergePolicy.html IOW, when the next commit occurs that closes and flushes the currently open segment. Nothing will happen to any existing 10GB segments, now or ever in the future since merging two 10GB segments would not be possible with a limit of only 15GB. Maybe you could clue us in as to what effect you are trying to achieve. I mean, why should any app care whether segments are 10GB or 15GB? -- Jack Krupansky On Sat, Jan 30, 2016 at 6:28 PM, Shawn Heisey <apa...@elyograg.org> wrote: > On 1/30/2016 7:31 AM, Zheng Lin Edwin Yeo wrote: > > I would like to find out, when I increase the maxMergedSegmentMB from > 10240 > > (10GB) to 15360 (15GB), will all the 10GB segments that were created > > previously be automatically merge to 15GB? > > Not necessarily. It will make those 10GB+ segments eligible for further > merging, whereas they would have been ineligible before the change. > > This might mean that one or more of those large segments will be merged > soon after the change and restart/reload, but I do not know when it > might happen. It would probably wait until at least one new segment was > created, at which time the merge policy would be consulted. > > Thanks, > Shawn > >
