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https://issues.apache.org/jira/browse/SOLR-3178?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13257664#comment-13257664
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Per Steffensen commented on SOLR-3178:
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I dont care about credit :-)
It is just that I put myself on as Assigned to indicate that I was working on
it. And I have been - with a pause of a few weeks because my product owner
prioritized me to look at something different (money talkes - you know :-) ). I
am soon ready to provide a full solution so why not wait for that. My solution
is a little bit different than yours (just had a very short peek at you patch)
but basically it is doing the same thing, but there is no need for both you and
my solution. I really hope you will wait until you see my contribution - it is
much more complete than what you have done until now, and we are already using
it with success in a highly concurrent pilot-production environment.
My contribution solves at least a few problems that yours doesnt seem to solve
(yet):
- It works with multi-document update request, providing fully detailed
feedback to the client about which document-updates failed (and why) and which
succeeded. I believe your solution will just result in a 409 HTTP response if
just one of many documents in the same request failed, leaving no information
to the user about which of the other documents in the request where
successfully handled, and if more of the documents (comming after the on that
did fail) would also have failed.
- It works (have been tested by heavily concurrent tests) in highly concurrent
environments. Looking shortly at you patch, I belive, that if two threads in
the server JVM overlaps in a way that is unfortunate enough, then it is
possible that data will not be stored or will be overwritten without an
exception being thrown to indicate that to the client.
I understand your point about doing this incrementally, and I have done that
internally. But since I am not a Solr committer it is hard to push too many
small partly-done features. If I had been a committer you would have been able
to follow the progress of my work more closely. But fact is, that I have a full
and well tested solution that I would like to provide as a contribution very
soon. I really hope you will wait for that, before committing different a
partly done solution to the same problems. Thanks a lot!
I would much rather want you to carefully read
http://wiki.apache.org/solr/Per%20Steffensen/Update%20semantics and provide
feedback and comments. I will deliver everything described there (and more)
very soon.
Regards, Per Steffensen
> Versioning - optimistic locking
> -------------------------------
>
> Key: SOLR-3178
> URL: https://issues.apache.org/jira/browse/SOLR-3178
> Project: Solr
> Issue Type: New Feature
> Components: update
> Affects Versions: 3.5
> Environment: All
> Reporter: Per Steffensen
> Assignee: Per Steffensen
> Labels: RDBMS, insert, locking, nosql, optimistic, uniqueKey,
> update, versioning
> Fix For: 4.0
>
> Attachments: SOLR-3178.patch
>
> Original Estimate: 168h
> Remaining Estimate: 168h
>
> In order increase the ability of Solr to be used as a NoSql database (lots of
> concurrent inserts, updates, deletes and queries in the entire lifetime of
> the index) instead of just a search index (first: everything indexed (in one
> thread), after: only queries), I would like Solr to support versioning to be
> used for optimistic locking.
> When my intent (see SOLR-3173) is to update an existing document, I will need
> to provide a version-number equal to "the version number I got when I fetched
> the existing document for update" plus one. If this provided version-number
> does not correspond to "the newest version-number of that document at the
> time of update" plus one, I will get a VersionConflict error. If it does
> correspond the document will be updated with the new one, so that "the newest
> version-number of that document" is NOW one higher than before the update.
> Correct but efficient concurrency handling.
> When my intent (see SOLR-3173) is to insert a new document, the version
> number provided will not be used - instead a version-number 0 will be used.
> According to SOLR-3173 insert will only succeed if a document with the same
> value on uniqueKey-field does not already exist.
> In general when talking about different versions of "the same document", of
> course we need to be able to identify when a document "is the same" - that,
> per definition, is when the values of the uniqueKey-fields are equal.
> The functionality provided by this issue is only really meaningfull when you
> run with "updateLog" activated.
> This issue might be solved more or less at the same time as SOLR-3173, and
> only one single SVN patch might be given to cover both issues.
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