That is an interesting problem. https://issues.apache.org/jira/browse/LUCENE-1292 will build a tag index that uses a ParallelReader to allow tag fields to be searchable. The tag index does not use the usual IndexWriter but uses a specialized realtime updateable index built for tags. Depending on the requirements, the Tag Index could be implemented in a variety of ways. It depends on how many tags, documents, and in this case users.
On Thu, May 22, 2008 at 5:44 AM, lucene user <[EMAIL PROTECTED]> wrote: > We have a requirement to inform users on a regular basis of new material on > which they have expressed interest. How are we to know what is "new" from > the point of view of a particular user? Our idea is to tag each new item in > some way (perhaps a date/time stamp in the lucene index indicating when the > new document was indexed) and remember when the last time we sent out an > alert to that user. > How should we tag the documents? With a date/time of indexing stamp? An > incrementing batch import ID number? Does it matter much? > > *I am reminded that ranges of dates and numbers, (as well as wild cards) > are > evaluated as if they were a large OR query covering all the values that > exist in the index. Lucene only finds exact matches - it does not do > comparisons. This means that ranges with lots of different values in them > are bad - and can actually crash with a 'too many clauses' exception if > there are enough distinct values to push the number of clauses over 1024. > Do > I understand this correctly?* > > *How do we handle existing documents which do not have such a new field > associated with them? Can we provide a default value for the existing > documents? * > > I did not find the place in the Lucene Documentation where it explains what > you get when you try to retrieve or search on a field that does not exist > in > the document. I remember it not being a problem, but I couldn't find it. > How > do I do this? What should I read? > > Thanks! >
