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1 : : /** @file queryoptimiser.h
2 : : * @brief Convert a Xapian::Query::Internal tree into an optimal PostList tree.
3 : : */
4 : : /* Copyright (C) 2007,2008,2009,2010 Olly Betts
5 : : * Copyright (C) 2008 Lemur Consulting Ltd
6 : : *
7 : : * This program is free software; you can redistribute it and/or
8 : : * modify it under the terms of the GNU General Public License as
9 : : * published by the Free Software Foundation; either version 2 of the
10 : : * License, or (at your option) any later version.
11 : : *
12 : : * This program is distributed in the hope that it will be useful,
13 : : * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 : : * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 : : * GNU General Public License for more details.
16 : : *
17 : : * You should have received a copy of the GNU General Public License
18 : : * along with this program; if not, write to the Free Software
19 : : * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
20 : : */
21 : :
22 : : #ifndef XAPIAN_INCLUDED_QUERYOPTIMISER_H
23 : : #define XAPIAN_INCLUDED_QUERYOPTIMISER_H
24 : :
25 : : #include "xapian/query.h"
26 : :
27 : : #include "database.h"
28 : : #include "localsubmatch.h"
29 : : #include "omenquireinternal.h"
30 : : #include "postlist.h"
31 : :
32 : : #include <list>
33 : : #include <vector>
34 : :
35 : : class MultiMatch;
36 : : struct PosFilter;
37 : :
38 : : class QueryOptimiser {
39 : : const Xapian::Database::Internal & db;
40 : :
41 : : Xapian::doccount db_size;
42 : :
43 : : LocalSubMatch & localsubmatch;
44 : :
45 : : MultiMatch * matcher;
46 : :
47 : : /** How many leaf subqueries there are.
48 : : *
49 : : * Used for scaling percentages when the highest weighted document doesn't
50 : : * "match all terms".
51 : : */
52 : : Xapian::termcount total_subqs;
53 : :
54 : : /** Optimise a Xapian::Query::Internal subtree into a PostList subtree.
55 : : *
56 : : * @param query The subtree to optimise.
57 : : * @param factor How much to scale weights for this subtree by.
58 : : *
59 : : * @return A PostList subtree.
60 : : */
61 : : PostList * do_subquery(const Xapian::Query::Internal * query,
62 : : double factor);
63 : :
64 : : /** Optimise an AND-like Xapian::Query::Internal subtree into a PostList
65 : : * subtree.
66 : : *
67 : : * @param query The subtree to optimise.
68 : : * @param factor How much to scale weights for this subtree by.
69 : : *
70 : : * @return A PostList subtree.
71 : : */
72 : : PostList * do_and_like(const Xapian::Query::Internal *query, double factor);
73 : :
74 : : /** Optimise an AND-like Xapian::Query::Internal subtree into a PostList
75 : : * subtree.
76 : : *
77 : : * @param query The subtree to optimise.
78 : : * @param factor How much to scale weights for this subtree by.
79 : : * @param and_plists Append new PostList subtrees to be combined with
80 : : * AND to this vector.
81 : : * @param pos_filters Append any positional filters to be applied to the
82 : : * tree to this list.
83 : : */
84 : : void do_and_like(const Xapian::Query::Internal *query, double factor,
85 : : std::vector<PostList *> & and_plists,
86 : : std::list<PosFilter> & pos_filters);
87 : :
88 : : /** Optimise an OR-like Xapian::Query::Internal subtree into a PostList
89 : : * subtree.
90 : : *
91 : : * @param query The subtree to optimise.
92 : : * @param factor How much to scale weights for this subtree by.
93 : : *
94 : : * @return A PostList subtree.
95 : : */
96 : : PostList * do_or_like(const Xapian::Query::Internal *query, double factor);
97 : :
98 : : /** Optimise a synonym Xapian::Query::Internal subtree into a PostList
99 : : *
100 : : * @param query The subtree to optimise.
101 : : * @param factor How much to scale weights for this subtree by.
102 : : *
103 : : * @return A PostList subtree.
104 : : */
105 : : PostList * do_synonym(const Xapian::Query::Internal *query, double factor);
106 : :
107 : : public:
108 : 246352 : QueryOptimiser(const Xapian::Database::Internal & db_,
109 : : LocalSubMatch & localsubmatch_,
110 : : MultiMatch * matcher_)
111 : 246352 : : db(db_), db_size(db.get_doccount()), localsubmatch(localsubmatch_),
112 : 246352 : matcher(matcher_), total_subqs(0) { }
113 : :
114 : 246352 : PostList * optimise_query(const Xapian::Query::Internal * query) {
115 : 246352 : return do_subquery(query, 1.0);
116 : : }
117 : :
118 : 246352 : Xapian::termcount get_total_subqueries() const { return total_subqs; }
119 : : };
120 : :
121 : : #endif // XAPIAN_INCLUDED_QUERYOPTIMISER_H
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