On Wed, 14 Dec 2005, jian chen wrote:
Hi,
I am pretty pessimistic about any DB directory implementation for Lucene.
The nature of the Lucene index files does not really fit well into a
relational database. Therefore, performance wise, the DB implementations
would suffer a lot. Basically, I would discourage anyone on the DB
implementation.
2 cents,
Jian
Berkeley DB is *not* a relational database. A relational database may be built
from it (see MySQL) but, by itself, it is not a relational database. It is a
simple way to persist key/values pairs organized in a Btree, Hashtable,
numbered record list, or queue.
http://www.sleepycat.com/docs/ref/intro/dbisnot.html
The Berkeley Java API C edition-based Lucene Index implementation is using 2
Btrees to store file-like structures. One Btree is a directory of files, the
other Btree is a directory of data blocks.
The advantage of using Berkeley DB over the file system for Lucene index data
is that, in a situation where index updates are frequent and concurrent,
Berkeley DB offers transactional protection - all the changes either go in,
atomiically, or not - and better concurrency by providing finer locking.
Andi..
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