Hi, > If I specify a precisionStep of 26 for a TrieDate field, what rough impact > should this have on both performance and index size?
This value is mostly useless, everything > 8 does slowdown the queries tot he speed of TermRangeQuery. > The input data has time in it, but the milliseconds per day is not needed for > the app. Will Lucene store only the top 64 minus 26 bits of data and discard > the low 26 bits? No, you may need to read the Javadocs of NumericRangeQuery, now updated with formulas: http://goo.gl/nyXQR The precisionStep is a count, after how many bits of the indexed value a new term starts. The original value is always indexed in full precision. Precision step of 4 for a 32 bit value(integer) means terms with these bit counts: All 32, left 28, left 24, left 20, left 16, left 12, left 8, left 4 bits of the value (total 8 terms/value). A precision step of 26 would index 2 terms: all 32 bits and one single term with the remaining 6 bits from the left. > I’ve read that a higher precisionStep will lower performance. Will a > precisionStep of 26 have dramatically lower performance when referencing > days (without time of day)? See above. The assumption that 26 will limit precision to days is wrong. > I suppose that the piece of information I am missing is whether trie > precisionStep simply affects some extra index table that trie keeps beyond > the raw data values or the data values themselves. It only affects how the value is indexed (how many terms), but not the value. Uwe --------------------------------------------------------------------- To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org For additional commands, e-mail: java-user-h...@lucene.apache.org
