Hi Jason, I'll create a JIRA and share what I have in mind on the corresponding collections API . Will update this thread once I have a draft ready.
Cheers, Rahul On Tue, Feb 24, 2026 at 6:57 AM Jason Gerlowski <[email protected]> wrote: > Hey Rahul, > > Awesome work on the core-admin API! > > Are your ideas around a "collection-admin" version of this API written > down anywhere, that someone could start in on it based on your > description? If not, would you be willing to put a JIRA writeup > together? > > Best, > > Jason > > On Mon, Feb 16, 2026 at 12:47 PM Rahul Goswami <[email protected]> > wrote: > > > > Hi all, > > Wanted to circle back with a late(ish) update on this effort. PR > > https://github.com/apache/solr/pull/3903 got merged a couple of weeks > back > > and* will be* available with Solr 9.11 (and Solr 10.1). It exposes a new > > CoreAdmin API as below: > > > > admin/cores?action=UPGRADECOREINDEX&core=<core-name> > > > > This serves as a convenient REST endpoint to upgrade an older Solr core > and > > can work in both sync and async modes. > > > > So where does this leave us with the state of index upgrade in Solr? > > > > For an index created in Solr 8.x and running Solr 9.11 or later 9.x > series: > > > > *SolrCloud mode* > > - Configure LatestVersionMergePolicyFactory > > < > https://github.com/apache/solr/blob/branch_9x/solr/core/src/java/org/apache/solr/index/LatestVersionMergePolicyFactory.java > > > > for the collection > > - Have a client program reindex the collection > > > > *Standalone mode* > > - Call /admin/cores?action=UPGRADECOREINDEX&core=<core-name>. > > It takes care of setting/resetting the merge policy under-the-hood and > > works in an optimized way by targeting only specific segments that need > to > > be rewritten. The API also maintains continuity across restarts without > > having to re-process data. > > > > All this while the index can remain open for searches and updates by any > > other application threads, aka zero downtime. > > Post this, when you upgrade to Solr 10.1, the index should open fine. > For a > > future upgrade to Solr 11, rinse and repeat the process while on Solr > 10.x. > > > > Thanks to David for the hard work in reviewing the PR > > https://github.com/apache/solr/pull/3903! > > > > I would ideally love to have a similar Collections API to make things > > easier on SolrCloud and have a rough approach in mind for the same, > > accounting for the different replica types etc. It can build upon the > > UPGRADECOREINDEX CoreAdmin API. However I may not have immediate > bandwidth > > to work on it. If someone would like to take this up, I'd be happy to > help > > out. > > > > Best, > > Rahul > > > > > > On Fri, Dec 5, 2025 at 11:47 AM Rahul Goswami <[email protected]> > wrote: > > > > > Hello, > > > Wanted to share an exciting development with the community. Recently > > > Lucene PR https://github.com/apache/lucene/pull/15431 ("Revise > strategy > > > to open an index") got merged. This makes Lucene look at individual > > > segments for backward compatibility rather than when the index was > first > > > created. Earlier this week Solr PR > > > https://github.com/apache/solr/pull/3883 got merged which provides a > > > merge policy to prevent older segments from merging. This should be > > > available in the next Solr 9.x release. A combination of these PRs > means if > > > an index was created in Solr 8.x, and later upgraded to 9.x, users > could > > > upgrade to Solr 10.x in the future without having to completely > rebuild the > > > index from an external source as is the requirement today. > > > > > > For indexes originally created in Solr 8.x, this enhancement would > require > > > them to reindex data in existing collections (onto the same collection) > > > once they are on the upcoming Solr 9.x release, and works if the > fields are > > > stored or docValues true (or a copy field destination, if not stored); > *without > > > any downtime.* > > > Rinse and repeat when they are on Solr 10.x, to prepare for upgrade to > > > Solr 11. > > > > > > Thanks to Michael Sokolov and David Smiley for the review inputs and > for > > > the help in seeing this through! > > > > > > An upcoming PR is in the works which provides an /admin/cores REST > > > endpoint that will do the reindexing automatically and in an optimized > way > > > by targeting only the data in older segments > > > https://github.com/apache/solr/pull/3903 > > > > > > Thanks, > > > Rahul Goswami > > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [email protected] > For additional commands, e-mail: [email protected] > >
