> It's not allways faster ... it really depends on how many matching terms there are in your range.
Does the cached RangeFilter's performance drop off relative to RangeQuery with a large number of matches then? > Wether you should cache all RangeFilters depends largely on how often you plan on re-opening your IndexReader Of course that's what I'd overlooked. There is no point in treating today's hits separately, because I'll have to recreate the cached RangeFilter everytime the index is re-opened anyhow, which means that I might as well add today to the cache too. I'd got it into my head that I'd only need to refresh the cached RangeFilters on midnight roll-over, but they will of course be invalidated whenever the index is re-opened. -----Original Message----- From: Chris Hostetter [mailto:[EMAIL PROTECTED] Sent: 15 July 2006 00:34 To: java-user@lucene.apache.org Subject: Re: Date ranges - getting the approach right : I gather I should prefer RangeQuery to ConstantScoreQuery+RangeFilter, : because it is faster not to use a Filter. However, I sometimes have to It's not allways faster ... it really depends on how many matching terms there are in your range. : In a year of 365 days with e-mail messages arriving every day, can I assume : that an inclusive date range of 20050713-20060713 in a RangeQuery is going : to contribute 365 clauses to a BooleanQuery? Can I assume that 5 years would : mean 5 x 365 = 1825 clauses? those assumptions are valid is you are also assuming at least one email message per day (the number of clauses a RangeQuery is based on the number of unique terms in that range which actually exist in your index). : An alternative would be to assume that my users are mostly going to ask for : e-mail arriving within the last day, two days, week, fortnight, month, : quarter, year, 5 years and pre-cache filters for these typical usage ranges : every time the clock rolls over, using a CachingWrapperFilter with : RangeFilter and to BooleanQuery that with a term query on today's date. That would be my suggestion ... use RangeFilter for everything, cache and pre-fetch any filters you expect to be very common (particularly things that your UI makes very easy). Wether you should cache all RangeFilters depends largely on how often you plan on re-opening your IndexReader -- if it's very frequent, then it may not be worth it; if it's very infrequent, you may want to use soemthing smarter then CachingWrapperFilter so you don't have a lot of one-off RangeFilters lieing arround forever taking up RAM. -Hoss --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
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