Attean::QueryPlanner - Query planner
This document describes Attean::QueryPlanner version 0.033
use v5.14;
use Attean;
my $planner = Attean::QueryPlanner->new();
my $default_graphs = [ Attean::IRI->new('http://example.org/') ];
my $plan = $planner->plan_for_algebra( $algebra, $model, $default_graphs );
my $iter = $plan->evaluate($model);
while (my $result = $iter->next()) {
say $result->as_string;
}
The Attean::QueryPlanner class is a base class implementing common
behavior for query planners. Subclasses will need to consume or compose the
Attean::API::JoinPlanner role.
Trivial sub-classes may consume Attean::API::NaiveJoinPlanner,
while more complex planners may choose to implement complex join planning
(e.g. Attean::IDPQueryPlanner).
- "new_temporary( $type )"
- Returns a new unique (in the context of the query planner) ID string that
may be used for things like fresh (temporary) variables. The
$type string is used in the generated name to aid
in identifying different uses for the names.
- "plan_for_algebra( $algebra, $model, \@active_graphs,
\@default_graphs )"
- Returns the first plan returned from
"plans_for_algebra".
- "plans_for_algebra( $algebra, $model, \@active_graphs,
\@default_graphs )"
- Returns Attean::API::Plan objects representing alternate query plans for
evaluating the query $algebra against the
$model, using the supplied
$active_graph.
- "simplify_path( $subject, $path, $object )"
- Return a simplified Attean::API::Algebra object corresponding to the given
property path.
- "new_projection( $plan, $distinct, @variable_names )"
- Return a new Attean::Plan::Project plan over
$plan, projecting the named variables.
$disctinct should be true if the caller can
guarantee that the resulting plan will produce distinct results, false
otherwise.
This method takes care of computing plan metadata such as the
resulting ordering.
- "bgp_join_plans( $bgp, $model, \@active_graphs, \@default_graphs,
\@interesting_order, \@plansA, \@plansB, ... )"
- Returns a list of alternative plans for the join of a set of triples. The
arguments @plansA,
@plansB, etc. represent alternative plans for each
triple participating in the join.
- "group_join_plans( $model, \@active_graphs, \@default_graphs,
\@interesting_order, \@plansA, \@plansB, ... )"
- Returns a list of alternative plans for the join of a set of sub-plans.
The arguments @plansA,
@plansB, etc. represent alternative plans for each
sub-plan participating in the join.
- "joins_for_plan_alternatives( $model, \@active_graphs,
\@default_graphs, $interesting, \@plan_A, \@plan_B, ... )"
- Returns a list of alternative plans that may all be used to produce
results matching the join of "plan_A",
" plan_B ">, etc. Each plan array
here (e.g. @plan_A) should contain equivalent
plans.
- "access_plans( $model, $active_graphs, $pattern )"
- Returns a list of alternative Attean::API::Plan objects that may be used
to produce results matching the Attean::API::TripleOrQuadPattern
$pattern in the context of
$active_graphs.
- "join_plans( $model, \@active_graphs, \@default_graphs, \@plan_left,
\@plan_right, $type [, $expr] )"
- Returns a list of alternative plans for the join of one plan from
@plan_left and one plan from
@plan_right. The join
$type must be one of
'inner', 'left', or
'minus', indicating the join algorithm to be used.
If $type is 'left', then
the optional $expr may be used to supply a filter
expression that should be used by the SPARQL left-join algorithm.
Please report any bugs or feature requests to through the GitHub
web interface at <https://github.com/kasei/attean/issues>.
Gregory Todd Williams
"<gwilliams@cpan.org>"
Copyright (c) 2014--2022 Gregory Todd Williams. This program is
free software; you can redistribute it and/or modify it under the same terms
as Perl itself.