Re: Indexing multiple languages
Tansley, Robert wrote: Hi all, The DSpace (www.dspace.org) currently uses Lucene to index metadata (Dublin Core standard) and extracted full-text content of documents stored in it. Now the system is being used globally, it needs to support multi-language indexing. I've looked through the mailing list archives etc. and it seems it's easy to plug in analyzers for different languages. What if we're trying to index multiple languages in the same site? Is it best to have: 1/ one index for all languages 2/ one index for all languages, with an extra language field so searches can be constrained to a particular language 3/ separate indices for each language? I don't fully understand the consequences in terms of performance for 1/, but I can see that false hits could turn up where one word appears in different languages (stemming could increase the changes of this). Also some languages' analyzers are quite dramatically different (e.g. the Chinese one which just treats every character as a separate token/word). On the other hand, if people are searching for proper nouns in metadata (e.g. DSpace) it may be advantageous to search all languages at once. I'm also not sure of the storage and performance consequences of 2/. Approach 3/ seems like it might be the most complex from an implementation/code point of view. But this will be the most robust solution. You have to differentiate between languages anyway, and as you pointed here, you can differentiate by adding a Keyword field for language, or you can create different indexes. If you need to use complex search strings over multiple fields and indexes then I recommend you to use the QueryParser to compute the search string. When you instantiate a QueryPArser you will need to provide an analyzer, that will be different for different languages. I think that the differences in performance won't be noticable between 2nd and 3rd solutions, but from maintenance point of view, I would choose the third solution. Of course there are other factors that must be take in account when designing such an application: number of documents to be indexed, number of document fields, index change frequency, server load (number of concurrent sessions), etc. Hope this hints help you a little, Best, Sergiu Does anyone have any thoughts or recommendations on this? Many thanks, Robert Tansley / Digital Media Systems Programme / HP Labs http://www.hpl.hp.com/personal/Robert_Tansley/ - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Indexing multiple languages
On Friday 03 Jun 2005 01:06, Bob Cheung wrote: For the StandardAnalyzer, will it have to be modified to accept different character encodings. We have customers in China, Taiwan and Hong Kong. Chinese data may come in 3 different encoding: Big5, GB and UTF8. What is the default encoding for the StandardAnalyser. The analysers themselves do not worry about encodings, per se. Java uses Unicode strings throughout, which is adequate enough to describing all languages. When reading in text files, it's a matter of letting the reader know which encoding the file is in, this helps Java to read in the text, and essentially map that encoding to the Unicode encoding. All the string operations, like analysing are done on these Unicode strings. So, the task is making sure the file reader you use to open a document for indexing is given the required information for correctly decoding your file. If you don't specify, Java will use one based on the locale that your OS uses. For me, that's Latin1 as I'm in Britain. This clearly is inadequate for non-Latin texts and wouldn't be able to read in Chinese texts properly as the Latin1 encoding doesn't support such characters. You need to specify Big5 yourself. Read the info on InputStreamReaders: http://java.sun.com/j2se/1.5.0/docs/api/java/io/InputStreamReader.html Andy Btw, I did try running the lucene demo (web template) to index the HTML files after I added one including English and Chinese characters. I was not able to search for any Chinese in that HTML file (returned no hits). I wonder whether I need to change some of the java programs to index Chinese and/or accept Chinese as search term. I was able to search for the HTML file if I used English word that appeared in the added HTML file. Thanks, Bob On May 31, 2005, Erik wrote: Jian - have you tried Lucene's StandardAnalyzer with Chinese? It will keep English as-is (removing stop words, lowercasing, and such) and separate CJK characters into separate tokens also. Erik On May 31, 2005, at 5:49 PM, jian chen wrote: Hi, Interesting topic. I thought about this as well. I wanted to index Chinese text with English, i.e., I want to treat the English text inside Chinese text as English tokens rather than Chinese text tokens. Right now I think maybe I have to write a special analyzer that takes the text input, and detect if the character is an ASCII char, if it is, assembly them together and make it as a token, if not, then, make it as a Chinese word token. So, bottom line is, just one analyzer for all the text and do the if/else statement inside the analyzer. I would like to learn more thoughts about this! Thanks, Jian On 5/31/05, Tansley, Robert [EMAIL PROTECTED] wrote: Hi all, The DSpace (www.dspace.org) currently uses Lucene to index metadata (Dublin Core standard) and extracted full-text content of documents stored in it. Now the system is being used globally, it needs to support multi-language indexing. I've looked through the mailing list archives etc. and it seems it's easy to plug in analyzers for different languages. What if we're trying to index multiple languages in the same site? Is it best to have: 1/ one index for all languages 2/ one index for all languages, with an extra language field so searches can be constrained to a particular language 3/ separate indices for each language? I don't fully understand the consequences in terms of performance for 1/, but I can see that false hits could turn up where one word appears in different languages (stemming could increase the changes of this). Also some languages' analyzers are quite dramatically different (e.g. the Chinese one which just treats every character as a separate token/word). On the other hand, if people are searching for proper nouns in metadata (e.g. DSpace) it may be advantageous to search all languages at once. I'm also not sure of the storage and performance consequences of 2/. Approach 3/ seems like it might be the most complex from an implementation/code point of view. Does anyone have any thoughts or recommendations on this? Many thanks, Robert Tansley / Digital Media Systems Programme / HP Labs http://www.hpl.hp.com/personal/Robert_Tansley/ - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For
Re: Indexing multiple languages
On Jun 2, 2005, at 9:06 PM, Bob Cheung wrote: Btw, I did try running the lucene demo (web template) to index the HTML files after I added one including English and Chinese characters. I was not able to search for any Chinese in that HTML file (returned no hits). I wonder whether I need to change some of the java programs to index Chinese and/or accept Chinese as search term. I was able to search for the HTML file if I used English word that appeared in the added HTML file. Bob - Andy provided thorough information on the StandardAnalyzer issue (in short, it deals with Unicode directly not encodings). As for the Lucene demo - you will have to adjust it to read the files in the proper encoding. The IndexFiles program indexes files using the default encoding which won't be sufficient for your purpose. The two files to check are HtmlDocument and FileDocument. These files read the HTML and text files that the demo indexes. Erik - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Indexing multiple languages
http://wiki.apache.org/jakarta-lucene/IndexingOtherLanguages [EMAIL PROTECTED] 6/3/2005 6:03:31 AM On Jun 2, 2005, at 9:06 PM, Bob Cheung wrote: Btw, I did try running the lucene demo (web template) to index the HTML files after I added one including English and Chinese characters. I was not able to search for any Chinese in that HTML file (returned no hits). I wonder whether I need to change some of the java programs to index Chinese and/or accept Chinese as search term. I was able to search for the HTML file if I used English word that appeared in the added HTML file. Bob - Andy provided thorough information on the StandardAnalyzer issue (in short, it deals with Unicode directly not encodings). As for the Lucene demo - you will have to adjust it to read the files in the proper encoding. The IndexFiles program indexes files using the default encoding which won't be sufficient for your purpose. The two files to check are HtmlDocument and FileDocument. These files read the HTML and text files that the demo indexes. Erik - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE: Indexing multiple languages
Hi You could use the ParalellReader for this if you have all documents in all languages. Then, the metadata fields can be stored in one of the field data files, while each languages gets its own field data file... max -Original Message- From: Paul Libbrecht [mailto:[EMAIL PROTECTED] Sent: Friday, June 03, 2005 14:23 To: java-user@lucene.apache.org Subject: Re: Indexing multiple languages Robert, Le 2 juin 05, à 21:42, Tansley, Robert a écrit : It seems that there are even more options -- 4/ One index, with a separate Lucene document for each (item,language) combination, with one field that specifies the language 5/ One index, one Lucene document per item, with field names that include the language (e.g. title_en, title_cn) I quite like 4, because you can search with no language constraint, or with one as Paul suggests below. You can in both cases. In the second, you need to expand the query (ie searching for carrot would search text_en:carrot or text_cn:carrot, which, I think is fair as long as you don't a two kilometer's list of languages. However, some non language-specific data might need to be repeated (e.g. dates), unless we had an extra Lucene document for all that. I wonder what the various pros and cons in terms of index size and performance would be in each case? I really don't have enough knowledge of Lucene to have any idea... If you separate the indices you won't, as far as I know, be able to query simultaneously (e.g. some text which, as well, is new enough). paul - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Indexing multiple languages
Tansley, Robert wrote: What if we're trying to index multiple languages in the same site? Is it best to have: 1/ one index for all languages 2/ one index for all languages, with an extra language field so searches can be constrained to a particular language 3/ separate indices for each language? I'd use 2/. In particular, use the same field for the content, title, etc., even if when produced by different analyzers. Have a lang field that names the language of the document. At query time, use an analyzer selected by the user's environment (e.g., HTTP lang header). If folks are getting false positives, where a term in another language that means something different is matching their query, they can use a lang pulldown to remove documents from other languages, implemented as a Lucene Filter. Doug - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE: Indexing multiple languages
Thanks all for the useful comments. It seems that there are even more options -- 4/ One index, with a separate Lucene document for each (item,language) combination, with one field that specifies the language 5/ One index, one Lucene document per item, with field names that include the language (e.g. title_en, title_cn) I quite like 4, because you can search with no language constraint, or with one as Paul suggests below. However, some non language-specific data might need to be repeated (e.g. dates), unless we had an extra Lucene document for all that. I wonder what the various pros and cons in terms of index size and performance would be in each case? I really don't have enough knowledge of Lucene to have any idea... Robert Tansley / Digital Media Systems Programme / HP Labs http://www.hpl.hp.com/personal/Robert_Tansley/ -Original Message- From: Paul Libbrecht [mailto:[EMAIL PROTECTED] Sent: 01 June 2005 04:10 To: java-user@lucene.apache.org Subject: Re: Indexing multiple languages Le 1 juin 05, à 01:12, Erik Hatcher a écrit : 1/ one index for all languages 2/ one index for all languages, with an extra language field so searches can be constrained to a particular language 3/ separate indices for each language? I would vote for option #2 as it gives the most flexibilty - you can query with or without concern for language. The way I've solved this is to make a different field-name per-language as our documents can be multilingual. What's then done is query expansion at query time: given a term-query for text, I duplicate it for each accepted language of the user with a factor related to the preference of the language (e.g. the q factor in Accept-Language http header). Presumably I could be using solution 2/ as well if my queries become too big, making several documents for each language of the document. I think it's very important to care about guessing the accepted languages of the user. Typically, the default behaviour of Google is to only give you matches in your primary language but then allow expansion in any language. On the other hand, if people are searching for proper nouns in metadata (e.g. DSpace) it may be advantageous to search all languages at once. This one may need particular treatment. Tell us your success! paul - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE: Indexing multiple languages
Hi Erik, I am a new comer to this list and please allow me to ask a dumb question. For the StandardAnalyzer, will it have to be modified to accept different character encodings. We have customers in China, Taiwan and Hong Kong. Chinese data may come in 3 different encoding: Big5, GB and UTF8. What is the default encoding for the StandardAnalyser. Btw, I did try running the lucene demo (web template) to index the HTML files after I added one including English and Chinese characters. I was not able to search for any Chinese in that HTML file (returned no hits). I wonder whether I need to change some of the java programs to index Chinese and/or accept Chinese as search term. I was able to search for the HTML file if I used English word that appeared in the added HTML file. Thanks, Bob On May 31, 2005, Erik wrote: Jian - have you tried Lucene's StandardAnalyzer with Chinese? It will keep English as-is (removing stop words, lowercasing, and such) and separate CJK characters into separate tokens also. Erik On May 31, 2005, at 5:49 PM, jian chen wrote: Hi, Interesting topic. I thought about this as well. I wanted to index Chinese text with English, i.e., I want to treat the English text inside Chinese text as English tokens rather than Chinese text tokens. Right now I think maybe I have to write a special analyzer that takes the text input, and detect if the character is an ASCII char, if it is, assembly them together and make it as a token, if not, then, make it as a Chinese word token. So, bottom line is, just one analyzer for all the text and do the if/else statement inside the analyzer. I would like to learn more thoughts about this! Thanks, Jian On 5/31/05, Tansley, Robert [EMAIL PROTECTED] wrote: Hi all, The DSpace (www.dspace.org) currently uses Lucene to index metadata (Dublin Core standard) and extracted full-text content of documents stored in it. Now the system is being used globally, it needs to support multi-language indexing. I've looked through the mailing list archives etc. and it seems it's easy to plug in analyzers for different languages. What if we're trying to index multiple languages in the same site? Is it best to have: 1/ one index for all languages 2/ one index for all languages, with an extra language field so searches can be constrained to a particular language 3/ separate indices for each language? I don't fully understand the consequences in terms of performance for 1/, but I can see that false hits could turn up where one word appears in different languages (stemming could increase the changes of this). Also some languages' analyzers are quite dramatically different (e.g. the Chinese one which just treats every character as a separate token/word). On the other hand, if people are searching for proper nouns in metadata (e.g. DSpace) it may be advantageous to search all languages at once. I'm also not sure of the storage and performance consequences of 2/. Approach 3/ seems like it might be the most complex from an implementation/code point of view. Does anyone have any thoughts or recommendations on this? Many thanks, Robert Tansley / Digital Media Systems Programme / HP Labs http://www.hpl.hp.com/personal/Robert_Tansley/ - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Indexing multiple languages
Hi, Interesting topic. I thought about this as well. I wanted to index Chinese text with English, i.e., I want to treat the English text inside Chinese text as English tokens rather than Chinese text tokens. Right now I think maybe I have to write a special analyzer that takes the text input, and detect if the character is an ASCII char, if it is, assembly them together and make it as a token, if not, then, make it as a Chinese word token. So, bottom line is, just one analyzer for all the text and do the if/else statement inside the analyzer. I would like to learn more thoughts about this! Thanks, Jian On 5/31/05, Tansley, Robert [EMAIL PROTECTED] wrote: Hi all, The DSpace (www.dspace.org) currently uses Lucene to index metadata (Dublin Core standard) and extracted full-text content of documents stored in it. Now the system is being used globally, it needs to support multi-language indexing. I've looked through the mailing list archives etc. and it seems it's easy to plug in analyzers for different languages. What if we're trying to index multiple languages in the same site? Is it best to have: 1/ one index for all languages 2/ one index for all languages, with an extra language field so searches can be constrained to a particular language 3/ separate indices for each language? I don't fully understand the consequences in terms of performance for 1/, but I can see that false hits could turn up where one word appears in different languages (stemming could increase the changes of this). Also some languages' analyzers are quite dramatically different (e.g. the Chinese one which just treats every character as a separate token/word). On the other hand, if people are searching for proper nouns in metadata (e.g. DSpace) it may be advantageous to search all languages at once. I'm also not sure of the storage and performance consequences of 2/. Approach 3/ seems like it might be the most complex from an implementation/code point of view. Does anyone have any thoughts or recommendations on this? Many thanks, Robert Tansley / Digital Media Systems Programme / HP Labs http://www.hpl.hp.com/personal/Robert_Tansley/ - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Indexing multiple languages
Jian - have you tried Lucene's StandardAnalyzer with Chinese? It will keep English as-is (removing stop words, lowercasing, and such) and separate CJK characters into separate tokens also. Erik On May 31, 2005, at 5:49 PM, jian chen wrote: Hi, Interesting topic. I thought about this as well. I wanted to index Chinese text with English, i.e., I want to treat the English text inside Chinese text as English tokens rather than Chinese text tokens. Right now I think maybe I have to write a special analyzer that takes the text input, and detect if the character is an ASCII char, if it is, assembly them together and make it as a token, if not, then, make it as a Chinese word token. So, bottom line is, just one analyzer for all the text and do the if/else statement inside the analyzer. I would like to learn more thoughts about this! Thanks, Jian On 5/31/05, Tansley, Robert [EMAIL PROTECTED] wrote: Hi all, The DSpace (www.dspace.org) currently uses Lucene to index metadata (Dublin Core standard) and extracted full-text content of documents stored in it. Now the system is being used globally, it needs to support multi-language indexing. I've looked through the mailing list archives etc. and it seems it's easy to plug in analyzers for different languages. What if we're trying to index multiple languages in the same site? Is it best to have: 1/ one index for all languages 2/ one index for all languages, with an extra language field so searches can be constrained to a particular language 3/ separate indices for each language? I don't fully understand the consequences in terms of performance for 1/, but I can see that false hits could turn up where one word appears in different languages (stemming could increase the changes of this). Also some languages' analyzers are quite dramatically different (e.g. the Chinese one which just treats every character as a separate token/word). On the other hand, if people are searching for proper nouns in metadata (e.g. DSpace) it may be advantageous to search all languages at once. I'm also not sure of the storage and performance consequences of 2/. Approach 3/ seems like it might be the most complex from an implementation/code point of view. Does anyone have any thoughts or recommendations on this? Many thanks, Robert Tansley / Digital Media Systems Programme / HP Labs http://www.hpl.hp.com/personal/Robert_Tansley/ - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Indexing multiple languages
Hi, Erik, Thanks for your info. No, I haven't tried it yet. I will give it a try and maybe produce some Chinese/English text search demo online. Currently I used Lucene as the indexing engine for Velocity mailing list search. I have a demo at www.jhsystems.net. It is yet another mailing list search for Velocity, but I combined date as well as full text search together. I only used lucene for indexing the textual content, and combined database search with lucene search in returning the results. The other interesting thought I have is: maybe it is possible to use Lucene's merge segments mechanism to write a java based simple file system. Which of course, does not require constant compact operation. The file system could be based on one file only, where segments are just part of the big file. It might be really efficient in terms of adding/deleting the objects all the time. Lastly, any comments welcome for www.jhsystems.net Velocity search. Thanks, Jian www.jhsystems.net On 5/31/05, Erik Hatcher [EMAIL PROTECTED] wrote: Jian - have you tried Lucene's StandardAnalyzer with Chinese? It will keep English as-is (removing stop words, lowercasing, and such) and separate CJK characters into separate tokens also. Erik On May 31, 2005, at 5:49 PM, jian chen wrote: Hi, Interesting topic. I thought about this as well. I wanted to index Chinese text with English, i.e., I want to treat the English text inside Chinese text as English tokens rather than Chinese text tokens. Right now I think maybe I have to write a special analyzer that takes the text input, and detect if the character is an ASCII char, if it is, assembly them together and make it as a token, if not, then, make it as a Chinese word token. So, bottom line is, just one analyzer for all the text and do the if/else statement inside the analyzer. I would like to learn more thoughts about this! Thanks, Jian On 5/31/05, Tansley, Robert [EMAIL PROTECTED] wrote: Hi all, The DSpace (www.dspace.org) currently uses Lucene to index metadata (Dublin Core standard) and extracted full-text content of documents stored in it. Now the system is being used globally, it needs to support multi-language indexing. I've looked through the mailing list archives etc. and it seems it's easy to plug in analyzers for different languages. What if we're trying to index multiple languages in the same site? Is it best to have: 1/ one index for all languages 2/ one index for all languages, with an extra language field so searches can be constrained to a particular language 3/ separate indices for each language? I don't fully understand the consequences in terms of performance for 1/, but I can see that false hits could turn up where one word appears in different languages (stemming could increase the changes of this). Also some languages' analyzers are quite dramatically different (e.g. the Chinese one which just treats every character as a separate token/word). On the other hand, if people are searching for proper nouns in metadata (e.g. DSpace) it may be advantageous to search all languages at once. I'm also not sure of the storage and performance consequences of 2/. Approach 3/ seems like it might be the most complex from an implementation/code point of view. Does anyone have any thoughts or recommendations on this? Many thanks, Robert Tansley / Digital Media Systems Programme / HP Labs http://www.hpl.hp.com/personal/Robert_Tansley/ - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
