/usr/lib/x86_64-linux-gnu/perl5/5.22/MongoDB/Op/_Explain.pm is in libmongodb-perl 1.2.2-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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# Copyright 2014 MongoDB, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
package MongoDB::Op::_Explain;
# Encapsulate code path for explain commands/queries
use version;
our $VERSION = 'v1.2.2';
use Moo;
use MongoDB::Op::_Command;
use MongoDB::Op::_Query;
use MongoDB::QueryResult::Filtered;
use MongoDB::_Constants;
use MongoDB::Error;
use MongoDB::CommandResult;
use MongoDB::_Types qw(
Document
);
use Types::Standard qw(
HashRef
InstanceOf
Str
);
use Tie::IxHash;
use boolean;
use namespace::clean;
has query => (
is => 'ro',
required => 1,
isa => InstanceOf['MongoDB::_Query'],
);
has db_name => (
is => 'ro',
required => 1,
isa => Str,
);
has coll_name => (
is => 'ro',
required => 1,
isa => Str,
);
with $_ for qw(
MongoDB::Role::_PrivateConstructor
MongoDB::Role::_ReadOp
);
sub execute {
my ( $self, $link, $topology ) = @_;
my $res =
$link->accepts_wire_version(4)
? $self->_command_explain( $link, $topology )
: $self->_legacy_explain( $link, $topology );
return $res;
}
sub _command_explain {
my ( $self, $link, $topology ) = @_;
my $cmd = Tie::IxHash->new( @{ $self->query->as_query_op->as_command } );
# XXX need to standardize error here
if (defined $self->query->modifiers->{hint}) {
# cannot use hint on explain, throw error
MongoDB::Error->throw(
message => "cannot use 'hint' with 'explain'",
);
}
my $op = MongoDB::Op::_Command->_new(
db_name => $self->db_name,
query => [
explain => $cmd,
@{ $self->read_concern->as_args }
],
query_flags => {},
read_preference => $self->read_preference,
bson_codec => $self->bson_codec,
);
my $res = $op->execute( $link, $topology );
return $res->{output};
}
sub _legacy_explain {
my ( $self, $link, $topology ) = @_;
my $new_query = $self->query->clone;
$new_query->modifiers->{'$explain'} = true;
# per David Storch, drivers *must* send a negative limit to instruct
# the query planner analysis module to add a LIMIT stage. For older
# explain implementations, it also ensures a cursor isn't left open.
$new_query->limit( -1 * abs( $new_query->limit ) );
return $new_query->execute->next;
}
1;
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