xapian-bindings/perl/Xapian/Enquire.pm

   1 package Xapian::Enquire;
   2
   3 =head1 NAME
   4
   5 Xapian::Enquire - Make queries against a database
   6
   7 =head1 DESCRIPTION
   8
   9 This class provides an interface to the information retrieval system for the
  10 purpose of searching.
  11
  12 =head1 METHODS
  13
  14 =over 4
  15
  16 =item new
  17
  18 =item set_query
  19
  20 takes either a ready made L<Xapian::Query> or a scalar containing
  21 a query, which in that case will be passed to L<Xapian::Query>'s
  22 constructor, together with any other passed arguments.
  23
  24 =item set_query_object <query>
  25
  26 =item get_query
  27
  28 =item matches <start> <size> [<check_at_least>]
  29
  30 Takes the start element, and maximum number of elements (and optionally
  31 the minimum number of matches to check), and returns an array tied to
  32 L<Xapian::MSet::Tied>.
  33
  34 =item get_matching_terms_begin
  35
  36 Returns a L<Xapian::TermIterator>, pointing to the start
  37 of the stream.
  38
  39 =item get_matching_terms_end
  40
  41 Returns a L<Xapian::TermIterator>, pointing to the end
  42 of the stream.
  43
  44 =item set_collapse_key <collapse_key>
  45
  46 =item set_docid_order <order>
  47
  48 Set the direction in which documents are ordered by document id
  49 in the returned MSet.
  50
  51 This order only has an effect on documents which would otherwise
  52 have equal rank.  When ordering by relevance without a sort key,
  53 this means documents with equal weight.  For a boolean match
  54 with no sort key, this means all documents.  And if a sort key
  55 is used, this means documents with equal sort key (and also equal
  56 weight if ordering on relevance before or after the sort key).
  57
  58 order can be ENQ_ASCENDING (the default, docids sort in ascending order),
  59 ENQ_DESCENDING (docds sort in descending order), or ENQ_DONT_CARE (docids sort
  60 in whatever order is most efficient for the backend.)
  61
  62 Note: If you add documents in strict date order, then a boolean
  63 search - i.e. set_weighting_scheme(Xapian::BoolWeight()) - with
  64 set_docid_order(Xapian::Enquire::DESCENDING) is an efficient
  65 way to perform "sort by date, newest first", and with
  66 set_docid_order(Xapian::Enquire::ASCENDING) a very efficient way
  67 to perform "sort by date, oldest first".
  68
  69 =item set_cutoff <percent_cutoff> [<weight_cutoff>]
  70
  71 =item set_sort_by_relevance
  72
  73 Set the sorting to be by relevance only.  This is the default.
  74
  75 =item set_sort_by_value <sort_key> [<ascending>]
  76
  77 Set the sorting to be by value only.
  78
  79 sort_key - value number to reorder on.  Sorting is with a
  80 string compare.  If ascending is true (the default) higher
  81 is better; if ascending is false, lower is better.
  82
  83 ascending - If true, document values which sort higher by
  84 string compare are better.  If false, the sort order
  85 is reversed.  (default true)
  86
  87 =item set_sort_by_value_then_relevance <sort_key> [<ascending>]
  88
  89 Set the sorting to be by value, then by relevance for documents
  90 with the same value.
  91
  92 sort_key - value number to reorder on.  Sorting is with a
  93 string compare.  If ascending is true (the default) higher
  94 is better; if ascending is false, lower is better.
  95
  96 ascending - If true, document values which sort higher by
  97 string compare are better.  If false, the sort order
  98 is reversed.  (default true)
  99
 100 =item set_sort_by_relevance_then_value <sort_key> [<ascending>]
 101
 102 Set the sorting to be by relevance then value.
 103
 104 Note that with the default BM25 weighting scheme parameters,
 105 non-identical documents will rarely have the same weight, so
 106 this setting will give very similar results to
 107 set_sort_by_relevance().  It becomes more useful with particular
 108 BM25 parameter settings (e.g. BM25Weight(1,0,1,0,0)) or custom
 109 weighting schemes.
 110
 111 sort_key - value number to reorder on.  Sorting is with a
 112 string compare.  If ascending is true (the default) higher
 113 is better; if ascending is false, lower is better.
 114
 115 ascending - If true, document values which sort higher by
 116 string compare are better.  If false, the sort order
 117 is reversed.  (default true)
 118
 119 =item set_sort_by_key <sorter> [<ascending>]
 120
 121 Set the sorting to be by key only.
 122
 123 sorter - the functor to use to build the key.
 124
 125 ascending - If true, keys which sort higher by
 126 string compare are better.  If false, the sort order
 127 is reversed.  (default true)
 128
 129 =item set_sort_by_key_then_relevance <sorter> [<ascending>]
 130
 131 Set the sorting to be by key, then by relevance for documents
 132 with the same key.
 133
 134 sorter - the functor to use to build the key.
 135
 136 ascending - If true, keys which sort higher by
 137 string compare are better.  If false, the sort order
 138 is reversed.  (default true)
 139
 140 =item set_sort_by_relevance_then_key <sorter> [<ascending>]
 141
 142 Set the sorting to be by relevance then key.
 143
 144 sorter - the functor to use to build the key.
 145
 146 ascending - If true, keys which sort higher by
 147 string compare are better.  If false, the sort order
 148 is reversed.  (default true)
 149
 150 =item get_mset
 151
 152 Get match set.
 153
 154 =item get_eset
 155
 156 Get set of query expansion terms.
 157
 158 =item get_description
 159
 160 Return a description of this object.
 161
 162 =back
 163
 164 =head1 SEE ALSO
 165
 166 L<Xapian::Query>,
 167 L<Xapian::Database>
 168
 169 =cut
 170 1;