天道酬勤,学无止境

inverted-index

what is the best way to build inverted index?

I'm building a small web search engine for searching about 1 million web pages and I want to know What is the best way to build the inverted index ? using the DBMS or What …? from many different views like storage cost, performance, speed of indexing and query? and I don't want to use any open source project for that I want to make my own one!

2021-06-12 21:42:54    分类:问答    indexing   search-engine   inverted-index

hadoop inverted-index without recurrence of file names

what i have in output is: word , file ----- ------ wordx Doc2, Doc1, Doc1, Doc1, Doc1, Doc1, Doc1, Doc1 what i want is: word , file ----- ------ wordx Doc2, Doc1 public static class LineIndexMapper extends MapReduceBase implements Mapper<LongWritable, Text, Text, Text> { private final static Text word = new Text(); private final static Text location = new Text(); public void map(LongWritable key, Text val, OutputCollector<Text, Text> output, Reporter reporter) throws IOException { FileSplit fileSplit = (FileSplit) reporter.getInputSplit(); String fileName = fileSplit.getPath().getName()

2021-06-12 16:04:15    分类:问答    hadoop   inverted-index

Cassandra 中的二级索引和倒排索引有什么区别?(What is the difference between a secondary index and an inverted index in Cassandra?)

问题 当我读到这两个时,我认为他们都在解释相同的方法,我用谷歌搜索但什么也没找到。 执行上有区别吗? Cassandra自己做二级索引,倒排索引要自己实现? 顺便说一下,哪个搜索速度更快? 回答1 主要区别在于 Cassandra 中的二级索引的分布方式与手动倒排索引的分布方式不同。 使用内置的二级索引,每个节点都对其本地存储的数据进行索引(使用 LocalPartitioner)。 通过手动索引,索引的分布独立于存储值的节点。 这意味着,对于内置索引,每个查询都必须转到每个节点,而如果您手动进行倒排索引,则只需转到一个节点(加上副本)来查询您要查找的值。 将索引存储在本地的优点之一是可以使用数据自动更新索引。 (尽管从 Cassandra 1.2 开始,原子批次可以用于此目的,尽管它们有点慢。) 这就是为什么不建议将 Cassandra 索引用于非常高的基数数据的原因。 如果在每个节点上查找,结果只有一两个,效率低下,手动倒排索引会更好。 如果您的查找返回许多结果,那么您无论如何都需要在每个节点上查找,这样内置索引才能正常工作。 使用 Cassandra 的内置索引的另一个优点是索引会延迟更新,因此您无需在每次更新时都进行读取。 (请参阅 CASSANDRA-2897。)对于具有高写入吞吐量的索引表,这可以显着提高速度。

2021-06-10 21:23:50    分类:技术分享    search   indexing   cassandra   inverted-index

What is the difference between a secondary index and an inverted index in Cassandra?

When I read about these two, I thought both of them are explaining the same approach, I googled but found nothing. Is the difference in implementation? Cassandra does the secondary index itself but inverted index has to be implemented by myself? Which is faster in searching, by the way?

2021-05-25 06:53:15    分类:问答    search   indexing   cassandra   inverted-index

Forward Index vs Inverted index Why?

I was reading about inverted index (used by the text search engines like Solr, Elastic Search etc) and as I understand (if we take "Person" as an example): The attribute to Person relationship is inverted: John -> PersonId(1), PersonId(2), PersonId(3) London -> PersonId(1), PersonId(2), PersonId(5) I can now search the person records for 'John who lives in London' Doesn't this solve all the problems? Why do we have the forward (or regular database index) at all? Or in other words, in what cases the regular indexing is useful? Please explain. Thanks.

2021-05-16 22:43:47    分类:问答    solr   elasticsearch   lucene   inverted-index   forward-indexing

Create indexes in solr on top of HBase

Is there anyway in which I can create indexes in Solr to perform full-text search from HBase for Near Real Time. I didn't wanted to store the whole text in my solr indexes. Made "stored=false" Note: - Keeping in mind, I am working on large datasets and want to do Near Real Time search. WE are talking TB/PB of data. UPDATED Cloudera Distribution : 5.4.x is used with Cloudera Search components. Solr : 4.10.x HBase : 1.0.x Indexer Service : Lily HBase Indexer with cloudera morphlines Is there any other NRT Indexer services or frameworks which can be used instead of Lily on Cloudera. Just a

2021-05-11 09:27:15    分类:问答    solr   hbase   cloudera   inverted-index

How to get byte offset in a file in python

I am making a inverted index using hadoop and python. I want to know how can I include the byte offset of a line/word in python. I need something like this hello hello.txt@1124 I need the locations for making a full inverted index. Please help.

2021-04-28 13:48:57    分类:问答    python   inverted-index

Loading a large dictionary using python pickle

I have a full inverted index in form of nested python dictionary. Its structure is : {word : { doc_name : [location_list] } } For example let the dictionary be called index, then for a word " spam ", entry would look like : { spam : { doc1.txt : [102,300,399], doc5.txt : [200,587] } } I used this structure as python dict are pretty optimised and it makes programming easier. for any word 'spam', the documents containig it can be given by : index['spam'].keys() and posting list for a document doc1 by: index['spam']['doc1'] At present I am using cPickle to store and load this dictionary. But the

2021-04-15 05:41:45    分类:问答    python   pickle   inverted-index

用列表值反转字典(Inverting a dictionary with list values)

问题 因此,我将此索引作为字典。 index = {'Testfil2.txt': ['nisse', 'hue', 'abe', 'pind'], 'Testfil1.txt': ['hue', 'abe', 'tosse', 'svend']} 我需要反转索引,因此它将是一个字典,其中值的重复项合并到一个键中,其中2个原始键作为值,如下所示: inverse = {'nisse' : ['Testfil2.txt'], 'hue' : ['Testfil2.txt', 'Testfil1.txt'], 'abe' : ['Testfil2.txt', 'Testfil1.txt'], 'pind' : ['Testfil2.txt'], 'tosse' : ['Testfil1.txt'], 'svend' : ['Testfil1.txt'] 是的,我手动输入了以上内容。 我的课本具有反转字典的功能: def invert_dict(d): inverse = dict() for key in d: val = d[key] if val not in inverse: inverse[val] = [key] else: inverse[val].append(key) return inverse 它适用于简单的key:value对 但是,当我尝试使用具有列表

2021-04-14 11:17:15    分类:技术分享    python   dictionary   indexing   inverted-index

Inverting a dictionary with list values

So, I have this index as a dict. index = {'Testfil2.txt': ['nisse', 'hue', 'abe', 'pind'], 'Testfil1.txt': ['hue', 'abe', 'tosse', 'svend']} I need to invert the index so it will be a dict with duplicates of values merged into one key with the 2 original keys as values, like this: inverse = {'nisse' : ['Testfil2.txt'], 'hue' : ['Testfil2.txt', 'Testfil1.txt'], 'abe' : ['Testfil2.txt', 'Testfil1.txt'], 'pind' : ['Testfil2.txt'], 'tosse' : ['Testfil1.txt'], 'svend' : ['Testfil1.txt'] Yes, I typed the above by hand. My textbook has this function for inverting dictionaries: def invert_dict(d)

2021-03-25 09:35:27    分类:问答    python   dictionary   indexing   inverted-index