: I have documents with 10 indexed fields and 10 million documents. : One of the index fields has ID-type value which is almost unique. when I : search with that almost-unique field it comes up in 12ms, but if I add : another criteria to the search it's very slow, like 5 secs. : : I don't use QueryParser but I created my own queries with BooleanQuery of : course. Is there anyway to optimize this? How can I influence Lucene to : search index that yields less documents first and followed by the other : indexes (the same concept used by some RDBMS that collects indexes : statistics/histogram)?
BooleanQuery should already do this ... if you look into the code, the "skipTo" methods in the ConjunctionScorer API are where the logic takes place -- each BooleanClause is asked to find the "first" document that it matches and then the others are told to "skipTo" the first match they have which that doc or later -- so a query that matches only one doc will result in the other clauses skipping to that doc. Since you haven't posted any code, it's hard to guess what might be going wrong for you -- but off the top of my head i can't help but wonder if you remembered to construct your BooleanClauses with Order.MUST (if you use Order.SHOULD then docs which match *either* clause will match ... and it's totally understandable that the query might be much slower) -Hoss
