A very handy new feature called query time joining
is coming to Lucene sooner than anticipated. While it was confirmed last month that it would be in Lucene 4.0, the most recent news from Apache indicates that it will be included sooner than expected in Lucene 3.6.
Just this week, query time joining
was added to Lucene 3.6, which is now preparing for a release. The main detail to take note of is the differences in the query time joining feature that will be in 3.6 and the version that was committed to the 4.0 trunk.
The version that has been committed in
the 4.0 trunk is about 3 times faster
than the one in 3.6. Also, the 4.0 version of this feature will support joining for fields that have multiple values for each document, but at least you will get to use the feature as early as 3.6.
This is yet another reason to prepare for a Lucene migration to 4.x when it's ready. The number of awesome new features is going to be too good to pass up.