Team, We are migrating from lucene version 2.3.1 to 4.1. We are migrating the indices as well, and we do this in two steps 2.3.1 to 3.6.2 and 3.6.2 to 4. We just call IndexUpgrader.upgrade(), using the IndexUpgraderMergePolicy. I see that, the upgrade() method actually calls a forcemerge(1) over the indices.
However, we have all our indices optimized and there are no deletes as well. This forcemerge(1) seems a very costly operation and since our index is already optimized, there is no space benefit as well. Is there a faster way to upgrade our indices (like reading the indices and modifying the headers, something of that sort)? We are not expecting any compaction during the process. Currently it takes 4 minutes for a GB of index to get migrated to 4.1 from 2.3.1. Any pointers would be appreciated. Thanks in advance. -- With Thanks and Regards, Ramprakash Ramamoorthy, Chennai, India.