1RDF::Trine::Pattern(3)User Contributed Perl DocumentationRDF::Trine::Pattern(3)
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NAME

6       RDF::Trine::Pattern - Class for basic graph patterns
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VERSION

9       This document describes RDF::Trine::Pattern version 1.019
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METHODS

12       "new ( @triples )"
13           Returns a new BasicGraphPattern structure.
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15       "construct_args"
16           Returns a list of arguments that, passed to this class'
17           constructor, will produce a clone of this algebra pattern.
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19       "triples"
20           Returns a list of triples belonging to this BGP.
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22       "type"
23       "sse"
24           Returns the SSE string for this algebra expression.
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26       "referenced_variables"
27           Returns a list of the variable names used in this algebra
28           expression.
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30       "definite_variables"
31           Returns a list of the variable names that will be bound after
32           evaluating this algebra expression.
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34       "clone"
35       "bind_variables ( \%bound )"
36           Returns a new pattern with variables named in %bound replaced by
37           their corresponding bound values.
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39       "subsumes ( $statement )"
40           Returns true if the pattern will subsume the $statement when
41           matched against a triple store.
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43       "merge_patterns ( @patterns )"
44           Given an array of patterns, this will merge them into one.
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46       "sort_for_join_variables"
47           Returns a new pattern object with the subpatterns of the referrant
48           sorted based on heuristics that ensure firstly that patterns can be
49           joined on the same variable and secondly on the usual selectivity
50           (i.e. how quickly the engine can drill down to the answer) of
51           triple patterns. Calls "subgroup", "sort_triples" and
52           "merge_patterns" in that order.
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54       "subgroup"
55           Splits the pattern object up in an array of pattern objects where
56           the same triple patterns occur. It will group on common variables,
57           so that triple patterns can be joined together is in a group
58           together. It will also group triples that have no connection to
59           other triples in a group. It will then order the groups, first by
60           number triples with common variables, then by number of literals,
61           then by the total number of terms that are not variables.
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63       "sort_triples"
64           Will sort the triple patterns based on heuristics that looks at how
65           many variables the patterns have, and where they occur, see
66           REFERENCES for details. Returns a new sorted pattern object.
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BUGS

69       Please report any bugs or feature requests to through the GitHub web
70       interface at <https://github.com/kasei/perlrdf/issues>.
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REFERENCES

73       The heuristics to order triple patterns in this module is strongly
74       influenced by The ICS-FORTH Heuristics-based SPARQL Planner (HSP)
75       <http://www.ics.forth.gr/isl/index_main.php?l=e&c=645>.
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AUTHOR

78       Gregory Todd Williams  "<gwilliams@cpan.org>"
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80       Kjetil Kjernsmo "<kjetilk@cpan.org>"
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83       Copyright (c) 2006-2012 Gregory Todd Williams. This program is free
84       software; you can redistribute it and/or modify it under the same terms
85       as Perl itself.
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89perl v5.30.0                      2019-07-26            RDF::Trine::Pattern(3)
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