Thanks a lot for the response. We did not change schema or config. We simply opened 4.5 indexes with 4.10 libraries. Thank you, Rajeswari
On 12/7/17, 3:17 PM, "Shawn Heisey" <apa...@elyograg.org> wrote: On 12/7/2017 1:27 PM, Natarajan, Rajeswari wrote: > We have upgraded solr from 4.5.1 to 4.10.4 and we see index size reduction. Trying to see if any optimization done to decrease the index sizes , couldn’t locate. If anyone knows why please share. Here's a history where you can see the a summary of the changes in Lucene's index format in various versions: https://lucene.apache.org/core/7_1_0/core/org/apache/lucene/codecs/lucene70/package-summary.html#History Looking over the history, I would guess that the changes mentioned between 4.5 and 4.10 would make little difference in most indexes, but for some configurations, might actually *increase* index size slightly. Chances are that the change would only happen after performing some kind of operation on the whole index, though. Did you do anything other than simply open the 4.5.1 index in 4.10.4 with the same config/schema? This would include things like running an optimize operation on the index, running IndexUpgrader on the index, completely reindexing from scratch rather than using the old index, or any number of other possibilities. Operations like those I mentioned would have eliminated deleted documents from the index, which can result in a size reduction. If you changed your schema at all, that can have an effect on index size -- in either direction. Thanks, Shawn