explain

lib/DBIx/Class/Helper/ResultSet/Explain.pm

@@ -0,0 +1,117 @@
+package DBIx::Class::Helper::ResultSet::Explain;
+
+use strict;
+use warnings;
+
+use DBIx::Introspector;
+
+# ABSTRACT: Get query plan for a ResultSet
+
+sub _introspector {
+   my $d = DBIx::Introspector->new(drivers => '2013-12.01');
+
+   $d->decorate_driver_connected(MSSQL => splain => 'GETUTCDATE()');
+   $d->decorate_driver_connected(
+      SQLite => splain => sub {
+         sub {
+            my ($dbh, $query) = @_;
+            my ($sql, @bind)  = @{$$query};
+
+            $sql =~ s/\s*\((.*)\)\s*/$1/;
+
+            shift->selectall_arrayref("EXPLAIN $sql", undef, @bind)
+         },
+      },
+   );
+   $d->decorate_driver_connected(
+      Pg => splain => sub {
+         sub {
+            my ($dbh, $query) = @_;
+            my ($sql, @bind)  = @{$$query};
+            shift->selectall_arrayref("EXPLAIN ANALYZE $sql", undef, @bind)
+         },
+      },
+   );
+
+   $d->decorate_driver_connected(
+      mysql => splain => sub {
+         sub {
+            my ($dbh, $query) = @_;
+            my ($sql, @bind)  = @{$$query};
+            shift->selectall_arrayref("EXPLAIN EXTENDED $sql", undef, @bind)
+         },
+      },
+   );
+
+   return $d;
+}
+
+use namespace::clean;
+
+my $i;
+
+sub explain {
+   $i ||= _introspector();
+
+   my $self = shift;
+
+   my $storage = $self->result_source->storage;
+   $storage->ensure_connected;
+   my $dbh = $storage->dbh;
+
+   $i->get($dbh, undef, 'splain')->($dbh, $self->as_query)
+}
+
+1;
+
+__END__
+
+=pod
+
+=head1 SYNOPSIS
+
+This module mostly makes sense to be used without setting as a component:
+
+ ues Devel::Dwarn;
+ Dwarn DBIx::Class::ResultSet::Explain::explain($rs)
+
+But as usual, if you prefer to use it as a component here's how:
+
+ package MyApp::Schema::ResultSet::Foo;
+
+ __PACKAGE__->load_components(qw{Helper::ResultSet::Explain});
+
+ ...
+
+ 1;
+
+And then in a script or something:
+
+ use Devel::Dwarn;
+ Dwarn $rs->explain;
+
+=head1 DESCRIPTION
+
+This is just a handy little tool that gives you the query plan for a given
+ResultSet.  The output is in no way normalized, so just treat it as a debug tool
+or something.  The only supported DB's are those listed below.  Have fun!
+
+See L<DBIx::Class::Helper::ResultSet/NOTE> for a nice way to apply it
+to your entire schema.
+
+=head1 EXAMPLE OUTPUT FROM SUPPORTED DB's
+
+=head2 SQlite
+
+=for exec
+perl maint/explain-out SQLite
+
+=head2 Pg
+
+=for exec
+perl maint/explain-out Pg
+
+=head2 mysql
+
+=for exec
+perl maint/explain-out mysql

maint/explain-out

@@ -0,0 +1,19 @@
+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+
+use Data::Dumper::Concise;
+
+use lib 't/lib';
+
+use A::Util;
+
+my $engine = shift;
+if ($engine eq 'SQLite') {
+   my $s = TestSchema->connect('dbi:SQLite::memory:');
+   $s->deploy;
+   print Dumper($s->resultset('Gnarly')->explain)
+} else {
+   print Dumper(A::Util::connect($engine, $engine)->resultset('Gnarly')->explain)
+}

t/lib/TestSchema.pm

@@ -56,7 +56,7 @@ sub generate_ddl {
           ($_ ne 'SQLite'
             ? (
                 add_drop_table => 1,
-                parser_args => { sources => ['HasDateOps'] })
+                parser_args => { sources => ['HasDateOps', 'Gnarly'] })
             : ( add_drop_table => 0 )
          )
       },

t/lib/TestSchema/ResultSet/Gnarly.pm

@@ -5,7 +5,7 @@ use warnings;
 # intentionally not using TestSchema::ResultSet
 use parent 'DBIx::Class::ResultSet';
 
-__PACKAGE__->load_components(qw{ Helper::ResultSet::Me Helper::ResultSet::ResultClassDWIM Helper::ResultSet::CorrelateRelationship Helper::ResultSet::SearchOr Helper::ResultSet::NoColumns });
+__PACKAGE__->load_components(qw{ Helper::ResultSet::Me Helper::ResultSet::ResultClassDWIM Helper::ResultSet::CorrelateRelationship Helper::ResultSet::SearchOr Helper::ResultSet::NoColumns Helper::ResultSet::Explain });
 
 sub with_id_plus_one {
    my $self = shift;

t/resultset/explain.t

@@ -0,0 +1,33 @@
+#!perl
+
+use Test::Roo;
+use Test::Fatal;
+use Data::Dumper::Concise;
+
+use lib 't/lib';
+
+with 'A::Role::TestConnect';
+
+sub rs { shift->schema->resultset('Gnarly') }
+
+test basic => sub {
+   my $self = shift;
+   my $rs = $self->rs;
+   SKIP: {
+      skip 'cannot test without a connection', 1 unless $self->connected;
+
+      my $s;
+      my $e = exception { $s = $rs->explain };
+      ok(!$e, 'valid SQL') or diag $e;
+      note(Dumper($s)) if $s;
+   }
+};
+
+run_me(SQLite => {
+   engine => 'SQLite',
+   connect_info => [ 'dbi:SQLite::memory:'],
+});
+run_me(Pg     => { engine => 'Pg'     });
+run_me(mysql  => { engine => 'mysql'  });
+
+done_testing;

weaver.ini

@@ -0,0 +1,23 @@
+[-Exec]
+[@CorePrep]
+
+[Name]
+
+[Region  / prelude]
+
+[Generic / SYNOPSIS]
+[Generic / DESCRIPTION]
+[Generic / OVERVIEW]
+
+[Leftovers]
+
+[Collect / ATTRIBUTES]
+command = attr
+
+[Collect / METHODS]
+command = method
+
+[Region  / postlude]
+
+[Authors]
+[Legal]