lib/Data/Query/Renderer/SQL/Slice/RowNum.pm

   1 package Data::Query::Renderer::SQL::Slice::RowNum;
   2
   3 use Data::Query::ExprHelpers;
   4 use Moo::Role;
   5
   6 with 'Data::Query::Renderer::SQL::Slice::SubqueryRemap';
   7
   8 sub slice_stability {
   9   (offset => 'check');
  10 }
  11
  12 sub _render_slice {
  13   my ($self, $dq) = @_;
  14   die "Slice's inner is not a Select"
  15     unless is_Select my $orig_select = $dq->{from};
  16   my %remapped = $self->_subquery_remap_select($orig_select);
  17   my $inside_select = Alias(
  18     $remapped{default_inside_alias},
  19     Select($remapped{inside_select_list}, $orig_select->{from}),
  20   );
  21   unless ($dq->{offset}) {
  22     return $self->render(
  23       Select(
  24         $remapped{outside_select_list},
  25         Where(
  26           Operator(
  27             { 'SQL.Naive' => '<=' },
  28             [
  29               Literal(SQL => 'ROWNUM'),
  30               $dq->{limit}
  31             ]
  32           ),
  33           $inside_select
  34         )
  35       )
  36     );
  37   }
  38   my ($limit_plus_offset, $offset_plus) = (
  39     { %{$dq->{limit}}, value => $dq->{limit}{value}+$dq->{offset}{value} },
  40     { %{$dq->{limit}}, value => $dq->{offset}{value}+1 }
  41   );
  42
  43   my $rownum_name = 'rownum__index';
  44
  45   if ($dq->{order_is_stable}) {
  46     return $self->render(
  47       Select(
  48         $remapped{outside_select_list},
  49         Where(
  50           Operator(
  51             { 'SQL.Naive' => '>=' },
  52             [ Identifier($rownum_name), $offset_plus ]
  53           ),
  54           Alias(
  55             $remapped{default_inside_alias},
  56             Select(
  57               [ @{$remapped{outside_select_list}},
  58                 Alias($rownum_name, Literal(SQL => 'ROWNUM')) ],
  59               Where(
  60                 Operator(
  61                   { 'SQL.Naive' => '<=' },
  62                   [ Literal(SQL => 'ROWNUM'), $limit_plus_offset ]
  63                 ),
  64                 $inside_select,
  65               )
  66             )
  67           )
  68         )
  69       )
  70     );
  71   } else {
  72     return $self->render(
  73       Select(
  74         $remapped{outside_select_list},
  75         Where(
  76           Operator(
  77             { 'SQL.Naive' => 'BETWEEN' },
  78             [ Identifier($rownum_name), $offset_plus, $limit_plus_offset ]
  79           ),
  80           Alias(
  81             $remapped{default_inside_alias},
  82             Select(
  83               [ @{$remapped{outside_select_list}},
  84                 Alias($rownum_name, Literal(SQL => 'ROWNUM')) ],
  85               $inside_select
  86             )
  87           )
  88         )
  89       )
  90     );
  91   }
  92 }
  93
  94 1;