Object
This is a simplified interface to the index. See the TUTORIAL for more information on how to use this class.
If you create an Index without any options, it'll simply create an index in memory. But this class is highly configurable and every option that you can supply to IndexWriter and QueryParser, you can also set here. Please look at the options for the constructors to these classes.
See;
default_input_field |
Default: "id". This specifies the default field that will be used when you add a simple string to the index using add_document or <<. |
id_field |
Default: "id". This field is as the field to search when doing searches on a term. For example, if you do a lookup by term "cat", ie index, this will be the field that is searched. |
key |
Default: nil. Expert: This should only be used if you really know what you are doing. Basically you can set a field or an array of fields to be the key for the index. So if you add a document with a same key as an existing document, the existing document will be replaced by the new object. Using a multiple field key will slow down indexing so it should not be done if performance is a concern. A single field key (or id) should be find however. Also, you must make sure that your key/keys are either untokenized or that they are not broken up by the analyzer. |
auto_flush |
Default: false. Set this option to true if you want the index automatically flushed every time you do a write (includes delete) to the index. This is useful if you have multiple processes accessing the index and you don't want lock errors. Setting :auto_flush to true has a huge performance impact so don't use it if you are concerned about performance. In that case you should think about setting up a DRb indexing service. |
lock_retry_time |
Default: 2 seconds. This parameter specifies how long to wait before retrying to obtain the commit lock when detecting if the IndexReader is at the latest version. |
close_dir |
Default: false. If you explicitly pass a Directory object to this class and you want Index to close it when it is closed itself then set this to true. |
use_typed_range_query |
Default: true. Use TypedRangeQuery instead of the standard RangeQuery when parsing range queries. This is useful if you have number fields which you want to perform range queries on. You won't need to pad or normalize the data in the field in anyway to get correct results. However, performance will be a lot slower for large indexes, hence the default. |
index = Index::Index.new(:analyzer => WhiteSpaceAnalyzer.new()) index = Index::Index.new(:path => '/path/to/index', :create_if_missing => false, :auto_flush => true) index = Index::Index.new(:dir => directory, :default_slop => 2, :handle_parse_errors => false)
You can also pass a block if you like. The index will be yielded and closed at the index of the box. For example;
Ferret::I.new() do |index| # do stuff with index. Most of your actions will be cached. end
# File lib/ferret/index.rb, line 91 def initialize(options = {}, &block) super() if options[:key] @key = options[:key] if @key.is_a?(Array) @key.flatten.map {|k| k.to_s.intern} end else @key = nil end if (fi = options[:field_infos]).is_a?(String) options[:field_infos] = FieldInfos.load(fi) end @close_dir = options[:close_dir] if options[:dir].is_a?(String) options[:path] = options[:dir] end if options[:path] @close_dir = true begin @dir = FSDirectory.new(options[:path], options[:create]) rescue IOError => io @dir = FSDirectory.new(options[:path], options[:create_if_missing] != false) end elsif options[:dir] @dir = options[:dir] else options[:create] = true # this should always be true for a new RAMDir @close_dir = true @dir = RAMDirectory.new end @dir.extend(MonitorMixin) unless @dir.kind_of? MonitorMixin options[:dir] = @dir options[:lock_retry_time]||= 2 @options = options if (!@dir.exists?("segments")) || options[:create] IndexWriter.new(options).close end options[:analyzer]||= Ferret::Analysis::StandardAnalyzer.new if options[:use_typed_range_query].nil? options[:use_typed_range_query] = true end @searcher = nil @writer = nil @reader = nil @options.delete(:create) # only create the first time if at all @auto_flush = @options[:auto_flush] || false if (@options[:id_field].nil? and @key.is_a?(Symbol)) @id_field = @key else @id_field = @options[:id_field] || :id end @default_field = (@options[:default_field]||= :*) @default_input_field = options[:default_input_field] || @id_field if @default_input_field.respond_to?(:intern) @default_input_field = @default_input_field.intern end @open = true @qp = nil if block yield self self.close end end
Adds a document to this index, using the provided analyzer instead of the local analyzer if provided. If the document contains more than IndexWriter::MAX_FIELD_LENGTH terms for a given field, the remainder are discarded.
There are three ways to add a document to the index. To add a document you can simply add a string or an array of strings. This will store all the strings in the "" (ie empty string) field (unless you specify the default_field when you create the index).
index << "This is a new document to be indexed" index << ["And here", "is another", "new document", "to be indexed"]
But these are pretty simple documents. If this is all you want to index you could probably just use SimpleSearch. So let's give our documents some fields;
index << {:title => "Programming Ruby", :content => "blah blah blah"} index << {:title => "Programming Ruby", :content => "yada yada yada"}
Or if you are indexing data stored in a database, you'll probably want to store the id;
index << {:id => row.id, :title => row.title, :date => row.date}
See FieldInfos for more information on how to set field properties.
# File lib/ferret/index.rb, line 263 def add_document(doc, analyzer = nil) @dir.synchronize do ensure_writer_open() if doc.is_a?(String) or doc.is_a?(Array) doc = {@default_input_field => doc} end # delete existing documents with the same key if @key if @key.is_a?(Array) query = @key.inject(BooleanQuery.new()) do |bq, field| bq.add_query(TermQuery.new(field, doc[field].to_s), :must) bq end query_delete(query) else id = doc[@key].to_s if id @writer.delete(@key, id) end end end ensure_writer_open() if analyzer old_analyzer = @writer.analyzer @writer.analyzer = analyzer @writer.add_document(doc) @writer.analyzer = old_analyzer else @writer.add_document(doc) end flush() if @auto_flush end end
Merges all segments from an index or an array of indexes into this index. You can pass a single Index::Index, Index::Reader, Store::Directory or an array of any single one of these.
This may be used to parallelize batch indexing. A large document collection can be broken into sub-collections. Each sub-collection can be indexed in parallel, on a different thread, process or machine and perhaps all in memory. The complete index can then be created by merging sub-collection indexes with this method.
After this completes, the index is optimized.
# File lib/ferret/index.rb, line 757 def add_indexes(indexes) @dir.synchronize do ensure_writer_open() indexes = [indexes].flatten # make sure we have an array return if indexes.size == 0 # nothing to do if indexes[0].is_a?(Index) indexes.delete(self) # don't merge with self indexes = indexes.map {|index| index.reader } elsif indexes[0].is_a?(Ferret::Store::Directory) indexes.delete(@dir) # don't merge with self indexes = indexes.map {|dir| IndexReader.new(dir) } elsif indexes[0].is_a?(IndexReader) indexes.delete(@reader) # don't merge with self else raise ArgumentError, "Unknown index type when trying to merge indexes" end ensure_writer_open @writer.add_readers(indexes) end end
Batch updates the documents in an index. You can pass either a Hash or an Array.
If you pass an Array then each value needs to be a Document or a Hash and each of those documents must have an :id_field which will be used to delete the old document that this document is replacing.
If you pass a Hash then the keys of the Hash will be considered the id's and the values will be the new documents to replace the old ones with.If the id is an Integer then it is considered a Ferret document number and the corresponding document will be deleted. If the id is a String or a Symbol then the id will be considered a term and the documents that contain that term in the :id_field will be deleted.
Note: No error will be raised if the document does not currently exist. A new document will simply be created.
# will replace the documents with the +id+'s id:133 and id:254 @index.batch_update({ '133' => {:id => '133', :content => 'yada yada yada'}, '253' => {:id => '253', :content => 'bla bla bal'} }) # will replace the documents with the Ferret Document numbers 2 and 92 @index.batch_update({ 2 => {:id => '133', :content => 'yada yada yada'}, 92 => {:id => '253', :content => 'bla bla bal'} }) # will replace the documents with the +id+'s id:133 and id:254 # this is recommended as it guarantees no duplicate keys @index.batch_update([ {:id => '133', :content => 'yada yada yada'}, {:id => '253', :content => 'bla bla bal'} ])
docs |
A Hash of id/document pairs. The set of documents to be updated |
# File lib/ferret/index.rb, line 626 def batch_update(docs) @dir.synchronize do ids = values = nil case docs when Array ids = docs.collect{|doc| doc[@id_field].to_s} if ids.include?(nil) raise ArgumentError, "all documents must have an #{@id_field} " "field when doing a batch update" end when Hash ids = docs.keys docs = docs.values else raise ArgumentError, "must pass Hash or Array, not #{docs.class}" end batch_delete(ids) ensure_writer_open() docs.each {|new_doc| @writer << new_doc } flush() end end
Closes this index by closing its associated reader and writer objects.
# File lib/ferret/index.rb, line 202 def close @dir.synchronize do if not @open raise(StandardError, "tried to close an already closed directory") end @searcher.close() if @searcher @reader.close() if @reader @writer.close() if @writer @dir.close() if @close_dir @open = false end end
Deletes a document/documents from the index. The method for determining the document to delete depends on the type of the argument passed.
If arg is an Integer then delete the document based on the internal document number. Will raise an error if the document does not exist.
If arg is a String then search for the documents with arg in the id field. The id field is either :id or whatever you set :id_field parameter to when you create the Index object. Will fail quietly if the no document exists.
If arg is a Hash or an Array then a batch delete will be performed. If arg is an Array then it will be considered an array of id's. If it is a Hash, then its keys will be used instead as the Array of document id's. If the id is an Integer then it is considered a Ferret document number and the corresponding document will be deleted. If the id is a String or a Symbol then the id will be considered a term and the documents that contain that term in the :id_field will be deleted.
# File lib/ferret/index.rb, line 517 def delete(arg) @dir.synchronize do if arg.is_a?(String) or arg.is_a?(Symbol) ensure_writer_open() @writer.delete(@id_field, arg.to_s) elsif arg.is_a?(Integer) ensure_reader_open() cnt = @reader.delete(arg) elsif arg.is_a?(Hash) or arg.is_a?(Array) batch_delete(arg) else raise ArgumentError, "Cannot delete for arg of type #{arg.class}" end flush() if @auto_flush end return self end
Returns true if document n has been deleted
# File lib/ferret/index.rb, line 553 def deleted?(n) @dir.synchronize do ensure_reader_open() return @reader.deleted?(n) end end
Retrieves a document/documents from the index. The method for retrieval depends on the type of the argument passed.
If arg is an Integer then return the document based on the internal document number.
If arg is a Range, then return the documents within the range based on internal document number.
If arg is a String then search for the first document with arg in the id field. The id field is either :id or whatever you set :id_field parameter to when you create the Index object.
# File lib/ferret/index.rb, line 451 def doc(*arg) @dir.synchronize do id = arg[0] if id.kind_of?(String) or id.kind_of?(Symbol) ensure_reader_open() term_doc_enum = @reader.term_docs_for(@id_field, id.to_s) return term_doc_enum.next? ? @reader[term_doc_enum.doc] : nil else ensure_reader_open(false) return @reader[*arg] end end end
iterate through all documents in the index. This method preloads the documents so you don't need to call load on the document to load all the fields.
# File lib/ferret/index.rb, line 489 def each @dir.synchronize do ensure_reader_open (0...@reader.max_doc).each do |i| yield @reader[i].load unless @reader.deleted?(i) end end end
Returns an Explanation that describes how doc scored against query.
This is intended to be used in developing Similarity implementations, and, for good performance, should not be displayed with every hit. Computing an explanation is as expensive as executing the query over the entire index.
# File lib/ferret/index.rb, line 823 def explain(query, doc) @dir.synchronize do ensure_searcher_open() query = do_process_query(query) return @searcher.explain(query, doc) end end
Returns the field_infos object so that you can add new fields to the index.
# File lib/ferret/index.rb, line 842 def field_infos @dir.synchronize do ensure_writer_open() return @writer.field_infos end end
Flushes all writes to the index. This will not optimize the index but it will make sure that all writes are written to it.
NOTE: this is not necessary if you are only using this class. All writes will automatically flush when you perform an operation that reads the index.
# File lib/ferret/index.rb, line 711 def flush() @dir.synchronize do if @reader if @searcher @searcher.close @searcher = nil end @reader.commit elsif @writer @writer.close @writer = nil end end end
Returns true if any documents have been deleted since the index was last flushed.
# File lib/ferret/index.rb, line 698 def has_deletions?() @dir.synchronize do ensure_reader_open() return @reader.has_deletions? end end
Returns an array of strings with the matches highlighted. The query can either a query String or a Ferret::Search::Query object. The doc_id is the id of the document you want to highlight (usually returned by the search methods). There are also a number of options you can pass;
field |
Default: @options. The default_field is the field that is usually highlighted but you can specify which field you want to highlight here. If you want to highlight multiple fields then you will need to call this method multiple times. |
excerpt_length |
Default: 150. Length of excerpt to show. Highlighted terms will be in the centre of the excerpt. Set to :all to highlight the entire field. |
num_excerpts |
Default: 2. Number of excerpts to return. |
pre_tag |
Default: "<b>". Tag to place to the left of the match. You'll probably want to change this to a "<span>" tag with a class. Try "033[36m" for use in a terminal. |
post_tag |
Default: "</b>". This tag should close the :pre_tag. Try tag "033[m" in the terminal. |
ellipsis |
Default: "...". This is the string that is appended at the beginning and end of excerpts (unless the excerpt hits the start or end of the field. Alternatively you may want to use the HTML entity … or the UTF-8 string "342200246". |
# File lib/ferret/index.rb, line 191 def highlight(query, doc_id, options = {}) @dir.synchronize do ensure_searcher_open() @searcher.highlight(do_process_query(query), doc_id, options[:field]||@options[:default_field], options) end end
optimizes the index. This should only be called when the index will no longer be updated very often, but will be read a lot.
# File lib/ferret/index.rb, line 729 def optimize() @dir.synchronize do ensure_writer_open() @writer.optimize() @writer.close() @writer = nil end end
This is a simple utility method for saving an in memory or RAM index to the file system. The same thing can be achieved by using the Index::Index#add_indexes method and you will have more options when creating the new index, however this is a simple way to turn a RAM index into a file system index.
directory |
This can either be a Store::Directory object or a String representing the path to the directory where you would like to store the index. |
create |
True if you'd like to create the directory if it doesn't exist or copy over an existing directory. False if you'd like to merge with the existing directory. This defaults to false. |
# File lib/ferret/index.rb, line 792 def persist(directory, create = true) synchronize do close_all() old_dir = @dir if directory.is_a?(String) @dir = FSDirectory.new(directory, create) elsif directory.is_a?(Ferret::Store::Directory) @dir = directory end @dir.extend(MonitorMixin) unless @dir.kind_of? MonitorMixin @options[:dir] = @dir @options[:create_if_missing] = true add_indexes([old_dir]) end end
Turn a query string into a Query object with the Index's QueryParser
# File lib/ferret/index.rb, line 833 def process_query(query) @dir.synchronize do ensure_searcher_open() return do_process_query(query) end end
Delete all documents returned by the query.
query |
The query to find documents you wish to delete. Can either be a string (in which case it is parsed by the standard query parser) or an actual query object. |
# File lib/ferret/index.rb, line 540 def query_delete(query) @dir.synchronize do ensure_writer_open() ensure_searcher_open() query = do_process_query(query) @searcher.search_each(query, :limit => :all) do |doc, score| @reader.delete(doc) end flush() if @auto_flush end end
Update all the documents returned by the query.
query |
The query to find documents you wish to update. Can either be a string (in which case it is parsed by the standard query parser) or an actual query object. |
new_val |
The values we are updating. This can be a string in which case the default field is updated, or it can be a hash, in which case, all fields in the hash are merged into the old hash. That is, the old fields are replaced by values in the new hash if they exist. |
index << {:id => "26", :title => "Babylon", :artist => "David Grey"} index << {:id => "29", :title => "My Oh My", :artist => "David Grey"} # correct index.query_update('artist:"David Grey"', {:artist => "David Gray"}) index["26"] #=> {:id => "26", :title => "Babylon", :artist => "David Gray"} index["28"] #=> {:id => "28", :title => "My Oh My", :artist => "David Gray"}
# File lib/ferret/index.rb, line 674 def query_update(query, new_val) @dir.synchronize do ensure_writer_open() ensure_searcher_open() docs_to_add = [] query = do_process_query(query) @searcher.search_each(query, :limit => :all) do |id, score| document = @searcher[id].load if new_val.is_a?(Hash) document.merge!(new_val) else new_val.is_a?(String) or new_val.is_a?(Symbol) document[@default_input_field] = new_val.to_s end docs_to_add << document @reader.delete(id) end ensure_writer_open() docs_to_add.each {|doc| @writer << doc } flush() if @auto_flush end end
Get the reader for this index.
NOTE |
This will close the writer from this index. |
# File lib/ferret/index.rb, line 218 def reader ensure_reader_open() return @reader end
Run a query through the Searcher on the index, ignoring scoring and starting at :start_doc and stopping when :limit matches have been found. It returns an array of the matching document numbers.
There is a big performance advange when using this search method on a very large index when there are potentially thousands of matching documents and you only want say 50 of them. The other search methods need to look at every single match to decide which one has the highest score. This search method just needs to find :limit number of matches before it returns.
start_doc |
Default: 0. The start document to start the search from. NOTE very carefully that this is not the same as the :offset parameter used in the other search methods which refers to the offset in the result-set. This is the document to start the scan from. So if you scanning through the index in increments of 50 documents at a time you need to use the last matched doc in the previous search to start your next search. See the example below. |
limit |
Default: 50. This is the number of results you want returned, also called the page size. Set :limit to :all to return all results. |
TODO: add option to return loaded documents instead
start_doc = 0 begin results = @searcher.scan(query, :start_doc => start_doc) yield results # or do something with them start_doc = results.last # start_doc will be nil now if results is empty, ie no more matches end while start_doc
# File lib/ferret/index.rb, line 430 def scan(query, options = {}) @dir.synchronize do ensure_searcher_open() query = do_process_query(query) @searcher.scan(query, options) end end
Run a query through the Searcher on the index. A TopDocs object is returned with the relevant results. The query is a built in Query object or a query string that can be parsed by the Ferret::QueryParser. Here are the options;
offset |
Default: 0. The offset of the start of the section of the result-set to return. This is used for paging through results. Let's say you have a page size of 10. If you don't find the result you want among the first 10 results then set :offset to 10 and look at the next 10 results, then 20 and so on. |
limit |
Default: 10. This is the number of results you want returned, also called the page size. Set :limit to :all to return all results |
sort |
A Sort object or sort string describing how the field should be sorted. A sort string is made up of field names which cannot contain spaces and the word "DESC" if you want the field reversed, all separated by commas. For example; "rating DESC, author, title". Note that Ferret will try to determine a field's type by looking at the first term in the index and seeing if it can be parsed as an integer or a float. Keep this in mind as you may need to specify a fields type to sort it correctly. For more on this, see the documentation for SortField |
filter |
a Filter object to filter the search results with |
filter_proc |
a filter Proc is a Proc which takes the doc_id, the score and the Searcher object as its parameters and returns a Boolean value specifying whether the result should be included in the result set. |
# File lib/ferret/index.rb, line 332 def search(query, options = {}) @dir.synchronize do return do_search(query, options) end end
Run a query through the Searcher on the index. A TopDocs object is returned with the relevant results. The query is a Query object or a query string that can be validly parsed by the Ferret::QueryParser. The Searcher#search_each method yields the internal document id (used to reference documents in the Searcher object like this; +searcher+) and the search score for that document. It is possible for the score to be greater than 1.0 for some queries and taking boosts into account. This method will also normalize scores to the range 0.0..1.0 when the max-score is greater than 1.0. Here are the options;
offset |
Default: 0. The offset of the start of the section of the result-set to return. This is used for paging through results. Let's say you have a page size of 10. If you don't find the result you want among the first 10 results then set :offset to 10 and look at the next 10 results, then 20 and so on. |
limit |
Default: 10. This is the number of results you want returned, also called the page size. Set :limit to :all to return all results |
sort |
A Sort object or sort string describing how the field should be sorted. A sort string is made up of field names which cannot contain spaces and the word "DESC" if you want the field reversed, all separated by commas. For example; "rating DESC, author, title". Note that Ferret will try to determine a field's type by looking at the first term in the index and seeing if it can be parsed as an integer or a float. Keep this in mind as you may need to specify a fields type to sort it correctly. For more on this, see the documentation for SortField |
filter |
a Filter object to filter the search results with |
filter_proc |
a filter Proc is a Proc which takes the doc_id, the score and the Searcher object as its parameters and returns a Boolean value specifying whether the result should be included in the result set. |
returns |
The total number of hits. |
eg.
index.search_each(query, options = {}) do |doc, score| puts "hit document number #{doc} with a score of #{score}" end
# File lib/ferret/index.rb, line 384 def search_each(query, options = {}) # :yield: doc, score @dir.synchronize do ensure_searcher_open() query = do_process_query(query) @searcher.search_each(query, options) do |doc, score| yield doc, score end end end
Get the searcher for this index.
NOTE |
This will close the writer from this index. |
# File lib/ferret/index.rb, line 225 def searcher ensure_searcher_open() return @searcher end
returns the number of documents in the index
# File lib/ferret/index.rb, line 739 def size() @dir.synchronize do ensure_reader_open() return @reader.num_docs() end end
Retrieves the term_vector for a document. The document can be referenced by either a string id to match the id field or an integer corresponding to Ferret's document number.
See Ferret::Index::IndexReader#term_vector
# File lib/ferret/index.rb, line 471 def term_vector(id, field) @dir.synchronize do ensure_reader_open() if id.kind_of?(String) or id.kind_of?(Symbol) term_doc_enum = @reader.term_docs_for(@id_field, id.to_s) if term_doc_enum.next? id = term_doc_enum.doc else return nil end end return @reader.term_vector(id, field) end end
# File lib/ferret/index.rb, line 808 def to_s buf = "" (0...(size)).each do |i| buf << self[i].to_s + "\n" if not deleted?(i) end buf end
Update the document referenced by the document number id if id is an integer or all of the documents which have the term id if id is a term.. For batch update of set of documents, for performance reasons, see batch_update
id |
The number of the document to update. Can also be a string representing the value in the id field. Also consider using the :key attribute. |
new_doc |
The document to replace the old document with |
# File lib/ferret/index.rb, line 569 def update(id, new_doc) @dir.synchronize do ensure_writer_open() delete(id) if id.is_a?(String) or id.is_a?(Symbol) @writer.commit else ensure_writer_open() end @writer << new_doc flush() if @auto_flush end end
returns the new reader if one is opened
# File lib/ferret/index.rb, line 864 def ensure_reader_open(get_latest = true) raise "tried to use a closed index" if not @open if @reader if get_latest latest = false begin latest = @reader.latest? rescue Lock::LockError => le sleep(@options[:lock_retry_time]) # sleep for 2 seconds and try again latest = @reader.latest? end if not latest @searcher.close if @searcher @reader.close return @reader = IndexReader.new(@dir) end end else if @writer @writer.close @writer = nil end return @reader = IndexReader.new(@dir) end return false end
# File lib/ferret/index.rb, line 891 def ensure_searcher_open() raise "tried to use a closed index" if not @open if ensure_reader_open() or not @searcher @searcher = Searcher.new(@reader) end end
# File lib/ferret/index.rb, line 851 def ensure_writer_open() raise "tried to use a closed index" if not @open return if @writer if @reader @searcher.close if @searcher @reader.close @reader = nil @searcher = nil end @writer = IndexWriter.new(@options) end
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