[
https://issues.apache.org/jira/browse/LUCENE-8264?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16449219#comment-16449219
]
Shawn Heisey commented on LUCENE-8264:
--------------------------------------
I'm with Erick. I had always understood that you could use IndexUpgrader to
migrate one major version at a time and use the index with a much newer
version, as long as all the field type classes writing data into the index are
still around in the newer version.
Now I'm hearing differently ... that any user who has successfully done this
has just gotten lucky, and that there's no guarantee for the future.
I am not greatly impacted by this, because I always prefer to build indexes
from scratch whenever I upgrade, and I recommend to anyone who will listen that
they do the same. We do have users with extremely large indexes, who have a
very difficult time reindexing from scratch.
> Allow an option to rewrite all segments
> ---------------------------------------
>
> Key: LUCENE-8264
> URL: https://issues.apache.org/jira/browse/LUCENE-8264
> Project: Lucene - Core
> Issue Type: Improvement
> Reporter: Erick Erickson
> Assignee: Erick Erickson
> Priority: Major
>
> For the background, see SOLR-12259.
> There are several use-cases that would be much easier, especially during
> upgrades, if we could specify that all segments get rewritten.
> One example: Upgrading 5x->6x->7x. When segments are merged, they're
> rewritten into the current format. However, there's no guarantee that a
> particular segment _ever_ gets merged so the 6x-7x upgrade won't necessarily
> be successful.
> How many merge policies support this is an open question. I propose to start
> with TMP and raise other JIRAs as necessary for other merge policies.
> So far the usual response has been "re-index from scratch", but that's
> increasingly difficult as systems get larger.
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
---------------------------------------------------------------------
To unsubscribe, e-mail: dev-unsubscr...@lucene.apache.org
For additional commands, e-mail: dev-h...@lucene.apache.org
