Em skrev:
Hi Per,
Solr provides the so called "UniqueKey"-field.
Refer to the Wiki to learn more:
http://wiki.apache.org/solr/UniqueKey
Belive the uniqueKey does not enforce a "unique key constraint", so that
you are not allowed to create a document with an id's when an document
with the same id already exists. So it is not the whole solution.
Optimistic locking (versioning)
... is not provided by Solr out of the box. If you add a new document
with the same UniqueKey it replaces the old one.
You have to do the versioning on your own (and keep in mind concurrent
updates).
Kind regards,
Em
Am 21.02.2012 13:50, schrieb Per Steffensen:
Hi
Does solr/lucene provide any mechanism for "unique key constraint" and
"optimistic locking (versioning)"?
Unique key constraint: That a client will not succeed creating a new
document in solr/lucene if a document already exists having the same
value in some field (e.g. an id field). Of course implemented right, so
that even though two or more threads are concurrently trying to create a
new document with the same value in this field, only one of them will
succeed.
Optimistic locking (versioning): That a client will only succeed
updating a document if this updated document is based on the version of
the document currently stored in solr/lucene. Implemented in the
optimistic way that clients during an update have to tell which version
of the document they fetched from Solr and that they therefore have used
as a starting-point for their updated document. So basically having a
version field on the document that clients increase by one before
sending to solr for update, and some code in Solr that only makes the
update succeed if the version number of the updated document is exactly
one higher than the version number of the document already stored. Of
course again implemented right, so that even though two or more thrads
are concurrently trying to update a document, and they all have their
updated document based on the current version in solr/lucene, only one
of them will succeed.
Or do I have to do stuff like this myself outside solr/lucene - e.g. in
the client using solr.
Regards, Per Steffensen
