> But - to come back to my original question... is there any way to have a > "natural order" of documents other that the DocId In Lucene?
No. -- Ian. On Wed, Aug 18, 2010 at 3:21 PM, Michel Nadeau <aka...@gmail.com> wrote: > Cool, so I'll try these things - > > * Replace timestamps with YYYYMMDD - will minimize unique terms count; > * Use NumericField's for dates and numbers - will remove all string sorting. > Thanks guys! > > -- > > But - to come back to my original question... is there any way to have a > "natural order" of documents other that the DocId In Lucene? For example, is > there any way to have an index automatically sorted on a specific field, > like : > > DocId Count Data > ------------------------------------- > 5 1 First test > 1 3 Otter > 8 4 Test > 2 8 Aloha > 10 11 Zulu > 9 17 Bingo > 3 46 Alpha test > 6 112 Tango > 4 120 Charlie test > 7 200 Kiwi > > Notice the DocId and Data random orders, but Count is sorted. That would be > the 'natural order' in the index, and searching for 'test' would return (in > that order) : > > DocId Count Data > ------------------------------------- > 5 1 First test > 3 46 Alpha test > 4 120 Charlie test > > Already sorted on the Count. > > Thanks! > > - Mike > aka...@gmail.com > > > On Tue, Aug 17, 2010 at 4:08 PM, Ian Lea <ian....@gmail.com> wrote: > >> Using NumericField for dates and other numbers is likely to help a >> lot, and removes padding problems. I'd try that first, or just sort >> the top n hits yourself. >> >> >> -- >> Ian. >> >> >> On Tue, Aug 17, 2010 at 8:46 PM, Michel Nadeau <aka...@gmail.com> wrote: >> > I could at least drop hours/mins/sec, we don't need them, so my timestamp >> > could become 'YYYYMMDD', that would cut the number of unique terms at >> least >> > for dates. >> > >> > What about my other question about numbers : *" We do pad our numbers >> with >> > zeros though (for example: 10 becomes 00000010, etc.) because we had >> trouble >> > with sorting (100 was smaller than 2) ; is that considered as "string >> > sorting" ? This might explain a part of the problem."* ? Thanks. >> > >> > - Mike >> > aka...@gmail.com >> > >> > >> > On Tue, Aug 17, 2010 at 3:40 PM, Erick Erickson <erickerick...@gmail.com >> >wrote: >> > >> >> Hmmm, I glossed over your comment about sorting the top 250. There's >> >> no reason that wouldn't work. >> >> >> >> Well, one way for, say, dates is to store separate fields. YYYY, MM, DD, >> >> HH, MM, SS, MS. That gives you say, 100 year terms, + 12 month >> >> +31 days + .... for a very small total. You pay the price though by >> >> having to change your queries and sorts to respect all 6 fields... >> >> >> >> But I'd only really go there after seeing if other options don't work. >> >> >> >> >> >> Best >> >> Erick >> >> >> >> On Tue, Aug 17, 2010 at 3:35 PM, Michel Nadeau <aka...@gmail.com> >> wrote: >> >> >> >> > Would our approach to limit the search top 250 documents (and then >> sort >> >> > these 250 documents) work fine ? Or even 250 unique terms with a lot >> of >> >> > users is bad on memory when sorting ? >> >> > >> >> > We didn't look at trie fields - I will do though, thanks for the tip ! >> >> > >> >> > We do store the original 'Data' field (only the 'SearchableData' field >> is >> >> > analyzed, all other fields are not analyzed), the users mainly sort on >> >> > numeric values; not a lot on string values (in fact I could compltely >> >> drop >> >> > the sort by string feature). We do pad our numbers with zeros though >> (for >> >> > example: 10 becomes 00000010, etc.) because we had trouble with >> sorting >> >> > (100 >> >> > was smaller than 2) ; is that considered as "string sorting" ? This >> might >> >> > explain a part of the problem. >> >> > >> >> > Why/how would I reduce the count of unique terms? >> >> > >> >> > >> >> > - Mike >> >> > aka...@gmail.com >> >> > >> >> > >> >> > On Tue, Aug 17, 2010 at 3:28 PM, Erick Erickson < >> erickerick...@gmail.com >> >> > >wrote: >> >> > >> >> > > If you have tens of millions of documents, almost all with unique >> >> fields >> >> > > that you're sorting on, you'll chew through memory like there's no >> >> > > tomorrow. >> >> > > >> >> > > Have you looked at trie fields? See: >> >> > > >> >> > > >> >> > >> >> >> http://www.lucidimagination.com/blog/2009/05/13/exploring-lucene-and-solrs-trierange-capabilities/ >> >> > > >> >> > > I'm a little concerned that the user can sort on Data. Any field >> used >> >> for >> >> > > sorting >> >> > > should NOT be analyzed, so unless you are indexing "Data" >> unanalyzed, >> >> > > that's >> >> > > a problem. And if you are sorting on strings unique to each >> document, >> >> > > that's >> >> > > also a memory hog. Not to mention whether capitalization counts. >> >> > > >> >> > > You might enumerate the terms in your index for each of the sortable >> >> > fields >> >> > > to figure out what the total number of unique terms each is and use >> >> that >> >> > as >> >> > > a basis for reducing their count.... >> >> > > >> >> > > HTH >> >> > > Erick >> >> > > >> >> > > On Tue, Aug 17, 2010 at 3:05 PM, Michel Nadeau <aka...@gmail.com> >> >> wrote: >> >> > > >> >> > > > Hi Erick, >> >> > > > >> >> > > > Here's some more details about our structure. First here's an >> example >> >> > of >> >> > > > document in our index : >> >> > > > >> >> > > > PrimaryKey = SJAsfsf353JHGada66GH6 (it's a hash) >> >> > > > DocType = X >> >> > > > Data = This is the data >> >> > > > SearchableContent = This is the data >> >> > > > DateCreated = <timestamp> >> >> > > > DateModified = <timestamp> >> >> > > > Counter1 = 17 >> >> > > > Counter2 = 3 >> >> > > > Average = 0.17 >> >> > > > Cost = 200 >> >> > > > >> >> > > > The users are able to sort on almost all fields: Data, >> DateCreated, >> >> > > > DateModified, Counter1, Counter2, Average, Cost. >> >> > > > >> >> > > > When we search, we always search on the 'SearchableContent' field >> and >> >> > we >> >> > > > have at least one filter on the DocType (because we have many >> >> document >> >> > > > types >> >> > > > in the same index). So a common search that would find the >> document >> >> > above >> >> > > > is >> >> > > > "data *AND DocType:X*" (we automatically add the "*AND DocType:X*" >> >> part >> >> > > > using Lucene Filters. >> >> > > > >> >> > > > I would say that the number of unique terms in the field being >> sorted >> >> > on >> >> > > is >> >> > > > very big - for example timestamps, almost all unique, counters, >> >> > average, >> >> > > > cost, data... so if a query finds 10M results, it's almost 10M >> >> > different >> >> > > > values to sort. About cache and warm-up queries : we don't use >> >> warm-up >> >> > > > queries -at all- because we have absolutely no idea of what users >> are >> >> > > going >> >> > > > to search for (they can search for absolutely anything). About >> >> > "returning >> >> > > > 10M" documents, right, we don't actually return the 10M documents, >> we >> >> > use >> >> > > > pagination to return documents X to Y of the 10M (and the 10M was >> >> only >> >> > an >> >> > > > example, it can be anywhere between 1K and 100M results). The >> >> > pagination >> >> > > > usually works fine and fast, our problem is really sorting. >> >> > > > >> >> > > > Our "Lucene Reader" process has 2GB of ram allowed, here's how I >> >> start >> >> > it >> >> > > - >> >> > > > >> >> > > > java -Xmx2048m -jar LuceneReader.jar >> >> > > > >> >> > > > The problem really seems to be a ram problem, but I can't be 100% >> >> sure >> >> > > (any >> >> > > > help about how to be sure is welcome). >> >> > > > >> >> > > > Our current idea of a solution would be to get maximum 250 results >> >> (the >> >> > > > more >> >> > > > relevant ones; more results than that is totally useless in our >> >> system) >> >> > > so >> >> > > > the sort should work fine on a small data set like that, but we >> want >> >> to >> >> > > > make >> >> > > > sure we're doing everything right before doing that so we don't >> run >> >> in >> >> > > the >> >> > > > same problems again. >> >> > > > >> >> > > > Thank you very much; let me know if you need any more details! >> >> > > > >> >> > > > - Mike >> >> > > > aka...@gmail.com >> >> > > > >> >> > > > >> >> > > > On Mon, Aug 16, 2010 at 4:01 PM, Erick Erickson < >> >> > erickerick...@gmail.com >> >> > > > >wrote: >> >> > > > >> >> > > > > Let's back up a minute. The number of matched records is not >> >> > > > > important when sorting, what's important is the number of unique >> >> > > > > terms in the field being sorted. Do you have any figures on >> that? >> >> One >> >> > > > > very common sorting issue is sorting on very fine date time >> >> > > resolutions, >> >> > > > > although your examples don't include that... >> >> > > > > >> >> > > > > Now, cache loading is an issue. The very first time you sort on >> a >> >> > > field, >> >> > > > > all the values are read into a cache. Is it possible this is the >> >> > source >> >> > > > > of your problems? You can cure this with warmup queries. The >> >> > take-away >> >> > > > > is that measuring the response time for the first sorted query >> is >> >> > > > > very misleading. >> >> > > > > >> >> > > > > Although if you're sorting on many, many, many email addresses, >> >> > > > > that could be "interesting". >> >> > > > > >> >> > > > > The comment "returning 10,000,000 documents" is, I hope, a >> >> > > > > misstatement. If you're trying to *return* 10M docs sorting >> >> > > > > is irrelevant compared to assembling that many documents. If >> >> > > > > you're trying to return the first 100 of 10M documents, it >> should >> >> > > > > work. >> >> > > > > >> >> > > > > Overall, we need more details on what you're sorting and what >> >> > > > > you're trying to return as well as how you're measuring before >> >> > > > > we can say much.... >> >> > > > > >> >> > > > > Along with how much memory you're giving your JVM to work with, >> >> > > > > what "exploding" means. Are you CPU bound? IO bound? Swapping? >> >> > > > > You need to characterize what is going wrong before worrying >> about >> >> > > > > solutions...... >> >> > > > > >> >> > > > > Best >> >> > > > > Erick >> >> > > > > >> >> > > > > On Mon, Aug 16, 2010 at 3:08 PM, Michel Nadeau < >> aka...@gmail.com> >> >> > > wrote: >> >> > > > > >> >> > > > > > Hi, >> >> > > > > > >> >> > > > > > we are building an application using Lucene and we have HUGE >> data >> >> > > sets >> >> > > > > (our >> >> > > > > > index contains millions and millions and millions of >> documents), >> >> > > which >> >> > > > > > obviously cause us very important problems when sorting. In >> fact, >> >> > we >> >> > > > > > disabled sorting completely because the servers were just >> >> exploding >> >> > > > when >> >> > > > > > trying to sort results in RAM. The users using the system can >> >> > search >> >> > > > for >> >> > > > > > whatever they want, so we never know how many results will be >> >> > > returned >> >> > > > - >> >> > > > > a >> >> > > > > > search can return 10 documents (no problem with sorting) or >> >> > > 10,000,000 >> >> > > > > > (huge >> >> > > > > > sorting problems). >> >> > > > > > >> >> > > > > > I woke up this morning and had a flash : is it possible with >> >> Lucene >> >> > > to >> >> > > > > have >> >> > > > > > a "natural sorting" of documents? For example, let's say I >> have 3 >> >> > > > columns >> >> > > > > I >> >> > > > > > want to be able to sort by : first name, last name, email; I >> >> would >> >> > > have >> >> > > > 3 >> >> > > > > > different indexes with the very same data but with a different >> >> > > primary >> >> > > > > key >> >> > > > > > for sorting. I know it's far fetched, and I have never seen >> >> > anything >> >> > > > like >> >> > > > > > that since I use Lucene, but we're just desperate... how >> people >> >> do >> >> > to >> >> > > > > have >> >> > > > > > huge data sets, a lot of users, and sort!? >> >> > > > > > >> >> > > > > > Thanks, >> >> > > > > > >> >> > > > > > Mike >> >> > > > > > >> >> > > > > >> >> > > > >> >> > > >> >> > >> >> >> > >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org >> For additional commands, e-mail: java-user-h...@lucene.apache.org >> >> > --------------------------------------------------------------------- To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org For additional commands, e-mail: java-user-h...@lucene.apache.org
