问题描述
我正在使用 RangeQuery 来获取数量在 0 到 2 之间的所有文档.当我执行查询时，Lucene 也会给我数量大于 2 的文档.我在这里错过了什么?
I'm using RangeQuery to get all the documents which have amount between say 0 to 2.
When i execute the query, Lucene gives me documents which have amount greater than 2 also. What am I missing here?
这是我的代码:
Term lowerTerm = new Term("amount", minAmount);
Term upperTerm = new Term("amount", maxAmount);
RangeQuery amountQuery = new RangeQuery(lowerTerm, upperTerm, true);
finalQuery.Add(amountQuery, BooleanClause.Occur.MUST);
这是我索引中的内容:
doc.Add(new Field("amount", amount.ToString(), Field.Store.YES, Field.Index.UN_TOKENIZED, Field.TermVector.YES));
推荐答案
UPDATE:就像@basZero在他的评论中所说，从Lucene 2.9开始，你可以添加数字字段到您的文档.只要记住使用 NumericRangeQuery 搜索时代替 RangeQuery.
UPDATE: Like @basZero said in his comment, starting with Lucene 2.9, you can add numeric fields to your documents. Just remember to use NumericRangeQuery instead of RangeQuery when you search.
Lucene 将数字视为单词，因此它们的顺序是字母顺序:
Lucene treats numbers as words, so their order is alphabetic:
0
1
12
123
2
22
这意味着对于 Lucene，12 介于 0 和 2 之间.如果要进行适当的数字范围，则需要索引数字零填充，然后执行 [0000 TO 0002] 的范围搜索.(您需要的填充量取决于预期的值范围).
That means that for Lucene, 12 is between 0 and 2. If you want to do a proper numerical range, you need to index the numbers zero-padded, then do a range search of [0000 TO 0002]. (The amount of padding you need depends on the expected range of values).
如果您有负数，只需为非负数添加另一个零.(错错了.查看更新)
If you have negative numbers, just add another zero for non-negative numbers. ( WRONG WRONG WRONG. See update)
如果您的数字包含小数部分，请保持原样，仅对整数部分进行零填充.
If your numbers include a fraction part, leave it as is, and zero-pad the integer part only.
例子:
<罢工>
-00002.12
-00001
000000
000001
000003.1415
000022
更新:负数有点棘手，因为 -1 按字母顺序排在 -2 之前.这篇文章给出了关于在 Lucene 中处理负数和一般数字的完整解释.基本上，您必须将数字编码"成使项目的顺序有意义的东西.
UPDATE: Negative numbers are a bit tricky, since -1 comes before -2 alphabetically. This article gives a complete explanation about dealing with negative numbers and numbers in general in Lucene. Basically, you have to "encode" numbers into something that makes the order of the items make sense.
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