I believe its still useful for TLOG replicas as well. When they gain leadership, and they replay the TLOG which could have the same issues that non leader NRT replicas have.
- Houston On Wed, Oct 18, 2023 at 8:26 AM David Smiley <david.w.smi...@gmail.com> wrote: > Thank you both. It helps to know that "_version"_ is for, I would say > succinctly, "NRT replication". I mean; that deserves to be said internally > in some places! > Might it be advantageous to imagine it being optional for non-NRT > replicas? I'm not sure if it saves anything or reduces complexity > anywhere. > Related question: Is the VersionInfo (with its striped VersionBucket > locks) related to this -- is it a vestige of "_version_" or is it for > something else? If it isn't for something else, then I could imagine it > being omitted for non-NRT; maybe a dummy implementation. BTW Bruno opened > an issue/PR on it yesterday -- > https://issues.apache.org/jira/browse/SOLR-17036 > > ~ David > > > On Wed, Oct 18, 2023 at 1:41 AM Ishan Chattopadhyaya < > ichattopadhy...@gmail.com> wrote: > > > Fyi, SOLR-5944, is unreadable, but introduced the concept of previous > > version or something like that. > > > > On Wed, 18 Oct, 2023, 10:35 am Mark Miller, <markrmil...@gmail.com> > wrote: > > > > > The primary reason is as Ishan says - so that update reorders from > leader > > > to replica can be handled in both normal and failure cases. > > > > > > It’s also true that a part of the reason that the per document, NRT > > design, > > > with versions, was chosen was a desire to support per document > optimistic > > > concurrency. > > > > > > On Tue, Oct 17, 2023 at 11:37 PM Ishan Chattopadhyaya < > > > ichattopadhy...@gmail.com> wrote: > > > > > > > Also DBQs use the version field to ensure they are applied correctly, > > > even > > > > if a DBQ is reordered > > > > > > > > On Wed, 18 Oct, 2023, 10:05 am Ishan Chattopadhyaya, < > > > > ichattopadhy...@gmail.com> wrote: > > > > > > > > > To ensure reordered updates are processed properly from leader to > > other > > > > > replicas in NRT replication mode. > > > > > > > > > > On Wed, 18 Oct, 2023, 9:55 am David Smiley, <dsmi...@apache.org> > > > wrote: > > > > > > > > > >> Question: Does the _version_ field have a purpose other than for > > > "atomic > > > > >> updates"? > > > > >> I know SolrCloud and/or having an UpdateLog insists on it. But I > > > don't > > > > >> know if it's for that feature alone, or for additional non-obvious > > > > >> internal > > > > >> workings of SolrCloud. Mostly I'm just asking to have a deeper > > > > >> understanding; the field doesn't bother me. If someone knows of > any > > > > docs > > > > >> on it or old interesting JIRAs to read, I'd appreciate it. > > > > >> > > > > >> ~ David Smiley > > > > >> Apache Lucene/Solr Search Developer > > > > >> http://www.linkedin.com/in/davidwsmiley > > > > >> > > > > > > > > > > > > > > >
