Erik Hatcher schrieb:
On Oct 11, 2004, at 4:31 AM, Christoph Goller wrote:
It seems that I did not think enough about the changes in QueryParser.
They definitely break the API. Sorry for doing this a little bit too
hastily. The following changes in QueryParser break the API:
1) Analyzer argument in both getFieldQuery methods
2) Analyzer argument in getRangeQuery
3) Additional minSimilarity argument in getFuzzyQuery
For 1-3, as long as the old signature was added back (and possibly
deprecated), there is no problem keeping the new signature.
Ok, I will do this in the head and in branch 1.4.2.
4) Default minimum similarity in query parser
5) FuzzyQuery.toString which also contains minSimilarity
These things clearly could break existing applications. So the best
solution would be to undo them. I am not sure whether we should undo
4 and 5, since they make fuzzy queries a little bit more usable and
QueryParser is able to read the new FuzzyQuery.toString. But other
applications may not ....
You sent a follow-up e-mail about moving the default value back to
zero. That seems fine to me. It's no big deal about
FuzzyQuery.toString - I doubt folks are relying on its output to parse
again, so you can leave that behavior as is. I just happened to have a
test case that relied on it, but no production code.
This mail was about the prefix length for FuzzyQuery which has a very
strong impact on the performance and on the semantics. In QueryParser
1.4.2 we only have a default value for minSimilarity, prefixLength is
not touched in QueryParser 1.4.2 and thus implicitly defaults to 0.
I think minSimilarity (and its default value in QueryParser) was mainly
introduce in order to avoid TooManyClausesExceptions, since it reduces
the number of terms going into the rewritten BooleanQuery. Furthermore,
I think the default value should remain 0.5 even for 1.4.2: Terms with a
Levenstein distance greater than have of their lenght (that's the meaning
of minSimilarity == 0.5f) do not seem similar to me.
Since 1.4.2 is already out, we would have to make a version 1.4.3.
OK, one more vote needed :-)
Maybe we should wait what Doug says.
Christoph
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