Yes, it's possible to run optimize on a live index. I wouldn't though, see: https://lucidworks.com/2017/10/13/segment-merging-deleted-documents-optimize-may-bad/
Lucene has _never_ guaranteed proper functioning of an index created with version X-2 with version X. It hasn't been super-obvious, but we had a long discussion about it on here: https://issues.apache.org/jira/browse/LUCENE-8264 but here's the most succinct statement of why upgrading more than one major version isn't really possible from Robert Muir: "I think the key issue here is Lucene is an index not a database. Because it is a lossy index and does not retain all of the user's data, its not possible to safely migrate some things automagically." So Lucene labors heroically to maintain 1 version back-compat, but that's all that's guaranteed. So I'd _really_ recommend you reindex if at all possible. Best, Erick Best, Erick On Thu, Aug 23, 2018 at 11:45 PM <dami...@gmail.com> wrote: > > Shawn, Is it possible to run optimize on the live collection? For example, > /solr/collection/update?commit=true&optimize=true > > On Wed, 22 Aug 2018 at 06:50, Shawn Heisey <apa...@elyograg.org> wrote: > > > On 8/21/2018 2:29 AM, Artjoms Laivins wrote: > > > We are running Solr cloud with 3 nodes v. 6.6.2 > > > We started with version 5 so we have some old index that we need safely > > move over to v. 7 now. > > > New data comes in several times per day. > > > Our questions are: > > > > > > Should we run IndexUpgrader tool on one slave node that is down or it is > > safe to run it while Solr is running and possible updates of the index are > > coming? > > > If yes, when we start it again will leader update this node with new > > data only or will it overwrite index? > > > > It might not be possible to upgrade two major versions like that, even > > with IndexUpgrader. There is only a guarantee of reading an index > > ORIGINALLY written by the previous major version. > > > > Even if it's possible to accomplish an upgrade, it is strongly > > recommended that you index from scratch anyway. > > > > You cannot run IndexUpgrader while Solr has the index open. The index > > must be completely closed. You cannot update an index while it is being > > upgraded. > > > > Thanks, > > Shawn > > > >
