Is there a new interface to add document and fields?
How do you handle the updating. Does the system require a unique ID per document?
Does this handle both RAM and FS Directories? That is what if a RAM Directory is used to search the index, does this solution use ram as another copy, or does it create an FS copy and then merge the results and then make another RAM Directory?
It would be great if you could contribute it. Probably since it's such a big change, we would first add it to the sandbox area and then after reviewing and testing it potentially adding it back into the core Lucene.
I am also cc'ing the dev board.
--Peter
On Thursday, October 17, 2002, at 06:47 AM, Scott Ganyo wrote:
This sounds like an excellent start and would certainly be useful in a
number of scenarios, but it is not quite as generally useful as it could be
given its asynchronous nature. Generally expected database behavior is that
when a change is committed (and not before) it is immediately viewable in
all new transactions (i.e. new readers).
Would it be difficult to modify your design to act more like a traditional
database? If such changes were made, would it still efficiently and
effectively solve the problems you mentioned below?
Scott
-----Original Message----- From: [EMAIL PROTECTED] [mailto:kiril.zack@;epiphany.com] Sent: Wednesday, October 16, 2002 5:45 PM To: [EMAIL PROTECTED] Subject: Concurency in LuceneMy company, Epiphany, has decided to integrate our products with Lucene. I'm leading this effort, and for this I have developed a solution around Lucene that allows concurrent processes to search, insert, update and delete documents. This solution solves the following: - concurrent writing (insert, update, delete) to the Index (see http://nagoya.apache.org/bugzilla/show_bug.cgi?id=12588 and http://www.mail-archive.com/lucene-user@;jakarta.apache.org/msg 01795.html - not-transactional nature of Lucene. Solution puts transaction around every insert, update and delete. All writes are guaranteed to be in the index eventually. - running out of file handles. - solution does all of the book-keeping, clients do not worry about when to open and close IndexReader/Writer. Technically one can do this after every operation, but creating/deleting of .lock file slows things down. In summary, every write (update, delete, insert) is made to log file first. There is a worker thread that wakes up every so often, examines the logs, and makes a decision on whether to propagate changes or not (this is configurable). If decision is to propagate changes, thread creates new log files, locks current log files, makes a copy of the new index, merges changes from logs to the index, and then hot-swaps the newly created index and deletes the old logs and index. At any given time, result from search will not contain deleted documents, but newly created/updated documents will not be in search result until merge is finished. Worker thread also keeps state of the logs/index in case of crash. Here is what were the driven factors to create this solution. Need for concurrent non-blocking writes (insert/update/delete) Need for deleted documents not to show up in the query result (Hits) once deleted Lucene does not handle crashes well. The mentality is "if in doubt, redo index" which does not work in some cases. Rebuilding of the index is fast, but in our case a) it takes too many non-Lucene related recourses (documents can be stored in database), b) high availability of search is a requirement - Lucene can leave .lock files. - Lucene keeps state (documents) in memory I wanted to see how much interest is out there for such a solution and whether Lucene developers feel that this should be part of Lucene. If there is enough interest I would like to donate this code to Lucene. Thanks, Kiril Zack -- To unsubscribe, e-mail: <mailto:lucene-user-unsubscribe@;jakarta.apache.org> For additional commands, e-mail: <mailto:lucene-user-help@;jakarta.apache.org>
-- To unsubscribe, e-mail: <mailto:lucene-user-unsubscribe@;jakarta.apache.org> For additional commands, e-mail: <mailto:lucene-user-help@;jakarta.apache.org>
