X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FResultSet.pm;h=574b2da18f3dea55c4e8ae5d5065e472921e3ce5;hb=c97338007ede15e7c62095a642b3de382a3508bd;hp=d8dcfcaa45255a3127422b2767426de101daea88;hpb=fe0708a2d68b5d34b6bc6f7e70164c3e569f1dd0;p=dbsrgits%2FDBIx-Class.git

diff --git a/lib/DBIx/Class/ResultSet.pm b/lib/DBIx/Class/ResultSet.pm
index d8dcfca..574b2da 100644
--- a/lib/DBIx/Class/ResultSet.pm
+++ b/lib/DBIx/Class/ResultSet.pm
@@ -829,7 +829,7 @@ sub find {
 
   # Run the query, passing the result_class since it should propagate for find
   my $rs = $self->search ($final_cond, {result_class => $self->result_class, %$attrs});
-  if ($rs->_resolved_attrs->{collapse}) {
+  if (keys %{$rs->_resolved_attrs->{collapse}}) {
     my $row = $rs->next;
     carp "Query returned more than one row" if $rs->next;
     return $row;
@@ -1038,7 +1038,7 @@ sub single {
 
   my $attrs = $self->_resolved_attrs_copy;
 
-  if ($attrs->{collapse}) {
+  if (keys %{$attrs->{collapse}}) {
     $self->throw_exception(
       'single() can not be used on resultsets prefetching has_many. Use find( \%cond ) or next() instead'
     );
@@ -1061,10 +1061,7 @@ sub single {
     $attrs->{where}, $attrs
   );
 
-  return @data
-    ? ($self->_construct_objects(@data))[0]
-    : undef
-  ;
+  return (@data ? ($self->_construct_object(@data))[0] : undef);
 }
 
 
@@ -1241,361 +1238,141 @@ sub next {
       : $self->cursor->next
   );
   return undef unless (@row);
-  my ($row, @more) = $self->_construct_objects(@row);
+  my ($row, @more) = $self->_construct_object(@row);
   $self->{stashed_objects} = \@more if @more;
   return $row;
 }
 
-# takes a single DBI-row of data and coinstructs as many objects
-# as the resultset attributes call for.
-# This can be a bit of an action at a distance - it takes as an argument
-# the *current* cursor-row (already taken off the $sth), but if
-# collapsing is requested it will keep advancing the cursor either
-# until the current row-object is assembled (the collapser was able to
-# order the result sensibly) OR until the cursor is exhausted (an
-# unordered collapsing resultset effectively triggers ->all)
-
-# FIXME: why the *FUCK* do we pass around DBI data by copy?! Sadly needs
-# assessment before changing...
-#
-sub _construct_objects {
+sub _construct_object {
   my ($self, @row) = @_;
-  my $attrs = $self->_resolved_attrs;
-  my $keep_collapsing = $attrs->{collapse};
-
-  my $res_index;
-=begin
-  do {
-    my $me_pref_col = $attrs->{_row_parser}->($row_ref);
-
-    my $container;
-    if ($keep_collapsing) {
-
-      # FIXME - we should be able to remove these 2 checks after the design validates
-      $self->throw_exception ('Collapsing without a top-level collapse-set... can not happen')
-        unless @{$me_ref_col->[2]};
-      $self->throw_exception ('Top-level collapse-set contains a NULL-value... can not happen')
-        if grep { ! defined $_ }  @{$me_pref_col->[2]};
-
-      my $main_ident = join "\x00", @{$me_pref_col->[2]};
-
-      if (! $res_index->{$main_ident}) {
-        # this is where we bail out IFF we are ordered, and the $main_ident changes
 
-        $res_index->{$main_ident} = {
-          all_me_pref => [,
-          index => scalar keys %$res_index,
-        };
-      }
-    }
-
-
-
-      $container = $res_index->{$main_ident}{container};
-    };
-
-    push @$container, [ @{$me_pref_col}[0,1] ];
-
-
-
-  } while (
-    $keep_collapsing
-      &&
-    do { $row_ref = [$self->cursor->next]; $self->{stashed_row} = $row_ref if @$row_ref; scalar @$row_ref }
-  );
-
-  # attempt collapse all rows with same collapse identity
-  if (@to_collapse > 1) {
-    my @collapsed;
-    while (@to_collapse) {
-      $self->_merge_result(\@collapsed, shift @to_collapse);
-    }
-  }
-=cut
-
-  my $mepref_structs = $self->_collapse_result($attrs->{as}, \@row, $keep_collapsing)
+  my $info = $self->_collapse_result($self->{_attrs}{as}, \@row)
     or return ();
-
-  my $rsrc = $self->result_source;
-  my $res_class = $self->result_class;
-  my $inflator = $res_class->can ('inflate_result');
-
-  my @objs =
-    $res_class->$inflator ($rsrc, @$mepref_structs);
-
-  if (my $f = $attrs->{record_filter}) {
-    @objs = map { $f->($_) } @objs;
-  }
-
-  return @objs;
+  my @new = $self->result_class->inflate_result($self->result_source, @$info);
+  @new = $self->{_attrs}{record_filter}->(@new)
+    if exists $self->{_attrs}{record_filter};
+  return @new;
 }
 
-
 sub _collapse_result {
-  my ( $self, $as_proto, $row_ref, $keep_collapsing ) = @_;
-  my $collapse = $self->_resolved_attrs->{collapse};
-  my $parser   = $self->result_source->_mk_row_parser( $as_proto, $collapse );
-  my $result   = [];
-  my $register = {};
-  my $rel_register = {};
-
-  my @row = @$row_ref;
-  do {
-    my $row = $parser->( \@row );
+  my ($self, $as_proto, $row) = @_;
 
-    # init register
-    $self->_check_register( $register, $row ) unless ( keys %$register );
+  my @copy = @$row;
 
-    $self->_merge_result( $result, $row, $rel_register )
-      if ( !$collapse
-      || ( $collapse = $self->_check_register( $register, $row ) ) );
+  # 'foo'         => [ undef, 'foo' ]
+  # 'foo.bar'     => [ 'foo', 'bar' ]
+  # 'foo.bar.baz' => [ 'foo.bar', 'baz' ]
 
-    } while (
-    $collapse
-    && do { @row = $self->cursor->next; $self->{stashed_row} = \@row if @row; }
+  my @construct_as = map { [ (/^(?:(.*)\.)?([^.]+)$/) ] } @$as_proto;
 
-  # run this as long as there is a next row and we are not yet done collapsing
-    );
-  return $result;
-}
-
-
-
-# Taubenschlag
-sub _check_register {
-  my ( $self, $register, $obj ) = @_;
-  return undef unless ( ref $obj eq 'ARRAY' && ref $obj->[2] eq 'ARRAY' );
-  my @ids = @{ $obj->[2] };
-  while ( defined( my $id = shift @ids ) ) {
-    return $register->{$id} if ( exists $register->{$id} && !@ids );
-    $register->{$id} = @ids ? {} : $obj unless ( exists $register->{$id} );
-    $register = $register->{$id};
-  }
-  return undef;
-}
+  my %collapse = %{$self->{_attrs}{collapse}||{}};
 
-sub _merge_result {
-  my ( $self, $result, $row, $register ) = @_;
-  return @$result = @$row if ( @$result == 0 );  # initialize with $row
+  my @pri_index;
 
-  my ( undef, $rels,   $ids )   = @$result;
-  my ( undef, $new_rels, $new_ids ) = @$row;
+  # if we're doing collapsing (has_many prefetch) we need to grab records
+  # until the PK changes, so fill @pri_index. if not, we leave it empty so
+  # we know we don't have to bother.
 
-  my @rels = keys %{ { %{$rels||{} }, %{ $new_rels||{} } } };
-  foreach my $rel (@rels) {
-    $register = $register->{$rel} ||= {};
+  # the reason for not using the collapse stuff directly is because if you
+  # had for e.g. two artists in a row with no cds, the collapse info for
+  # both would be NULL (undef) so you'd lose the second artist
 
-    my $new_data = $new_rels->{$rel};
-    my $data   = $rels->{$rel};
-    @$data = [@$data] unless ( ref $data->[0] eq 'ARRAY' );
+  # store just the index so we can check the array positions from the row
+  # without having to contruct the full hash
 
-    $self->_check_register( $register, $data->[0] )
-      unless ( keys %$register );
-
-    if ( my $found = $self->_check_register( $register, $new_data ) ) {
-      $self->_merge_result( $found, $new_data, $register );
-    }
-    else {
-      push( @$data, $new_data );
+  if (keys %collapse) {
+    my %pri = map { ($_ => 1) } $self->result_source->_pri_cols;
+    foreach my $i (0 .. $#construct_as) {
+      next if defined($construct_as[$i][0]); # only self table
+      if (delete $pri{$construct_as[$i][1]}) {
+        push(@pri_index, $i);
+      }
+      last unless keys %pri; # short circuit (Johnny Five Is Alive!)
     }
   }
-  return 1;
-}
-
-=begin
-
-# two arguments: $as_proto is an arrayref of column names,
-# $row_ref is an arrayref of the data. If none of the row data
-# is defined we return undef (that's copied from the old
-# _collapse_result). Next we decide whether we need to collapse
-# the resultset (i.e. we prefetch something) or not. $collapse
-# indicates that. The do-while loop will run once if we do not need
-# to collapse the result and will run as long as _merge_result returns
-# a true value. It will return undef if the current added row does not
-# match the previous row. A bit of stashing and cursor magic is
-# required so that the cursor is not mixed up.
-
-# "$rows" is a bit misleading. In the end, there should only be one
-# element in this arrayref. 
-
-sub _collapse_result {
-    my ( $self, $as_proto, $row_ref ) = @_;
-    my $has_def;
-    for (@$row_ref) {
-        if ( defined $_ ) {
-            $has_def++;
-            last;
-        }
-    }
-    return undef unless $has_def;
-
-    my $collapse = $self->_resolved_attrs->{collapse};
-    my $rows     = [];
-    my @row      = @$row_ref;
-    do {
-        my $i = 0;
-        my $row = { map { $_ => $row[ $i++ ] } @$as_proto };
-        $row = $self->result_source->_parse_row($row, $collapse);
-        unless ( scalar @$rows ) {
-            push( @$rows, $row );
-        }
-        $collapse = undef unless ( $self->_merge_result( $rows, $row ) );
-      } while (
-        $collapse
-        && do { @row = $self->cursor->next; $self->{stashed_row} = \@row if @row; }
-      );
 
-    return $rows->[0];
+  # no need to do an if, it'll be empty if @pri_index is empty anyway
 
-}
+  my %pri_vals = map { ($_ => $copy[$_]) } @pri_index;
 
-# _merge_result accepts an arrayref of rows objects (again, an arrayref of two elements)
-# and a row object which should be merged into the first object.
-# First we try to find out whether $row is already in $rows. If this is the case
-# we try to merge them by iteration through their relationship data. We call
-# _merge_result again on them, so they get merged.
-
-# If we don't find the $row in $rows, we append it to $rows and return undef.
-# _merge_result returns 1 otherwise (i.e. $row has been found in $rows).
-
-sub _merge_result {
-    my ( $self, $rows, $row ) = @_;
-    my ( $columns, $rels ) = @$row;
-    my $found = undef;
-    foreach my $seen (@$rows) {
-        my $match = 1;
-        foreach my $column ( keys %$columns ) {
-            if (   defined $seen->[0]->{$column} ^ defined $columns->{$column}
-                or defined $columns->{$column}
-                && $seen->[0]->{$column} ne $columns->{$column} )
-            {
-
-                $match = 0;
-                last;
-            }
-        }
-        if ($match) {
-            $found = $seen;
-            last;
-        }
-    }
-    if ($found) {
-        foreach my $rel ( keys %$rels ) {
-            my $old_rows = $found->[1]->{$rel};
-            $self->_merge_result(
-                ref $found->[1]->{$rel}->[0] eq 'HASH' ? [ $found->[1]->{$rel} ]
-                : $found->[1]->{$rel},
-                ref $rels->{$rel}->[0] eq 'HASH' ? [ $rels->{$rel}->[0], $rels->{$rel}->[1] ]
-                : $rels->{$rel}->[0]
-            );
-
-  my $attrs = $self->_resolved_attrs;
-  my ($keep_collapsing, $set_ident) = @{$attrs}{qw/collapse _collapse_ident/};
-
-  # FIXME this is temporary, need to calculate in _resolved_attrs
-  $set_ident ||= { me => [ $self->result_source->_pri_cols ], pref => {} };
-
-  my @cur_row = @$row_ref;
-  my (@to_collapse, $last_ident);
-
-  do {
-    my $row_hr = { map { $as_proto->[$_] => $cur_row[$_] } (0 .. $#$as_proto) };
-
-    # see if we are switching to another object
-    # this can be turned off and things will still work
-    # since _merge_prefetch knows about _collapse_ident
-#    my $cur_ident = [ @{$row_hr}{@$set_ident} ];
-    my $cur_ident = [];
-    $last_ident ||= $cur_ident;
-
-#    if ($keep_collapsing = Test::Deep::eq_deeply ($cur_ident, $last_ident)) {
-#      push @to_collapse, $self->result_source->_parse_row (
-#        $row_hr,
-#      );
-#    }
-  } while (
-    $keep_collapsing
-      &&
-    do { @cur_row = $self->cursor->next; $self->{stashed_row} = \@cur_row if @cur_row; }
-  );
+  my @const_rows;
 
-  die Dumper \@to_collapse;
+  do { # no need to check anything at the front, we always want the first row
 
+    my %const;
 
-  # attempt collapse all rows with same collapse identity
-  if (@to_collapse > 1) {
-    my @collapsed;
-    while (@to_collapse) {
-      $self->_merge_result(\@collapsed, shift @to_collapse);
+    foreach my $this_as (@construct_as) {
+      $const{$this_as->[0]||''}{$this_as->[1]} = shift(@copy);
     }
-    @to_collapse = @collapsed;
-  }
 
-  # still didn't fully collapse
-  $self->throw_exception ('Resultset collapse failed (theoretically impossible). Maybe a wrong collapse_ident...?')
-    if (@to_collapse > 1);
+    push(@const_rows, \%const);
 
-  return $to_collapse[0];
-}
+  } until ( # no pri_index => no collapse => drop straight out
+      !@pri_index
+    or
+      do { # get another row, stash it, drop out if different PK
 
+        @copy = $self->cursor->next;
+        $self->{stashed_row} = \@copy;
 
-# two arguments: $as_proto is an arrayref of 'as' column names,
-# $row_ref is an arrayref of the data. The do-while loop will run
-# once if we do not need to collapse the result and will run as long as
-# _merge_result returns a true value. It will return undef if the
-# current added row does not match the previous row, which in turn
-# means we need to stash the row for the subsequent ->next call
-sub _collapse_result {
-  my ( $self, $as_proto, $row_ref ) = @_;
-
-  my $attrs = $self->_resolved_attrs;
-  my ($keep_collapsing, $set_ident) = @{$attrs}{qw/collapse _collapse_ident/};
+        # last thing in do block, counts as true if anything doesn't match
 
-  die Dumper [$as_proto, $row_ref, $keep_collapsing, $set_ident ];
+        # check xor defined first for NULL vs. NOT NULL then if one is
+        # defined the other must be so check string equality
 
+        grep {
+          (defined $pri_vals{$_} ^ defined $copy[$_])
+          || (defined $pri_vals{$_} && ($pri_vals{$_} ne $copy[$_]))
+        } @pri_index;
+      }
+  );
 
-  my @cur_row = @$row_ref;
-  my (@to_collapse, $last_ident);
-
-  do {
-    my $row_hr = { map { $as_proto->[$_] => $cur_row[$_] } (0 .. $#$as_proto) };
-
-    # see if we are switching to another object
-    # this can be turned off and things will still work
-    # since _merge_prefetch knows about _collapse_ident
-#    my $cur_ident = [ @{$row_hr}{@$set_ident} ];
-    my $cur_ident = [];
-    $last_ident ||= $cur_ident;
+  my $alias = $self->{attrs}{alias};
+  my $info = [];
 
-#    if ($keep_collapsing = eq_deeply ($cur_ident, $last_ident)) {
-#      push @to_collapse, $self->result_source->_parse_row (
-#        $row_hr,
-#      );
-#    }
-  } while (
-    $keep_collapsing
-      &&
-    do { @cur_row = $self->cursor->next; $self->{stashed_row} = \@cur_row if @cur_row; }
-  );
+  my %collapse_pos;
 
-  # attempt collapse all rows with same collapse identity
-}
-=cut
+  my @const_keys;
 
-# Takes an arrayref of me/pref pairs and a new me/pref pair that should
-# be merged on a preexisting matching me (or should be pushed into $merged
-# as a new me/pref pair for further invocations). It should be possible to
-# use this function to collapse complete ->all results,  provided _collapse_result() is adjusted
-# to provide everything to this sub not to barf when $merged contains more than one 
-# arrayref)
-sub _merge_prefetch {
-  my ($self, $merged, $next_row) = @_;
-
-  unless (@$merged) {
-    push @$merged, $next_row;
-    return;
+  foreach my $const (@const_rows) {
+    scalar @const_keys or do {
+      @const_keys = sort { length($a) <=> length($b) } keys %$const;
+    };
+    foreach my $key (@const_keys) {
+      if (length $key) {
+        my $target = $info;
+        my @parts = split(/\./, $key);
+        my $cur = '';
+        my $data = $const->{$key};
+        foreach my $p (@parts) {
+          $target = $target->[1]->{$p} ||= [];
+          $cur .= ".${p}";
+          if ($cur eq ".${key}" && (my @ckey = @{$collapse{$cur}||[]})) {
+            # collapsing at this point and on final part
+            my $pos = $collapse_pos{$cur};
+            CK: foreach my $ck (@ckey) {
+              if (!defined $pos->{$ck} || $pos->{$ck} ne $data->{$ck}) {
+                $collapse_pos{$cur} = $data;
+                delete @collapse_pos{ # clear all positioning for sub-entries
+                  grep { m/^\Q${cur}.\E/ } keys %collapse_pos
+                };
+                push(@$target, []);
+                last CK;
+              }
+            }
+          }
+          if (exists $collapse{$cur}) {
+            $target = $target->[-1];
+          }
+        }
+        $target->[0] = $data;
+      } else {
+        $info->[0] = $const->{$key};
+      }
+    }
   }
 
+  return $info;
 }
 
 =head2 result_source
@@ -1766,7 +1543,7 @@ sub _count_subq_rs {
 
   # if we multi-prefetch we group_by something unique, as this is what we would
   # get out of the rs via ->next/->all. We *DO WANT* to clobber old group_by regardless
-  if ( $attrs->{collapse}  ) {
+  if ( keys %{$attrs->{collapse}}  ) {
     $sub_attrs->{group_by} = [ map { "$attrs->{alias}.$_" } @{
       $rsrc->_identifying_column_set || $self->throw_exception(
         'Unable to construct a unique group_by criteria properly collapsing the '
@@ -1886,32 +1663,30 @@ sub all {
       $self->throw_exception("all() doesn't take any arguments, you probably wanted ->search(...)->all()");
   }
 
-  if (my $c = $self->get_cache) {
-    return @$c;
-  }
+  return @{ $self->get_cache } if $self->get_cache;
 
-  my @objects;
+  my @obj;
 
-  if ($self->_resolved_attrs->{collapse}) {
+  if (keys %{$self->_resolved_attrs->{collapse}}) {
     # Using $self->cursor->all is really just an optimisation.
     # If we're collapsing has_many prefetches it probably makes
     # very little difference, and this is cleaner than hacking
-    # _construct_objects to survive the approach
+    # _construct_object to survive the approach
     $self->cursor->reset;
     my @row = $self->cursor->next;
     while (@row) {
-      push(@objects, $self->_construct_objects(@row));
+      push(@obj, $self->_construct_object(@row));
       @row = (exists $self->{stashed_row}
                ? @{delete $self->{stashed_row}}
                : $self->cursor->next);
     }
   } else {
-    @objects = map { $self->_construct_objects(@$_) } $self->cursor->all;
+    @obj = map { $self->_construct_object(@$_) } $self->cursor->all;
   }
 
-  $self->set_cache(\@objects) if $self->{attrs}{cache};
+  $self->set_cache(\@obj) if $self->{attrs}{cache};
 
-  return @objects;
+  return @obj;
 }
 
 =head2 reset
@@ -1981,14 +1756,19 @@ sub _rs_update_delete {
   # simplify the joinmap and maybe decide if a grouping (and thus subquery) is necessary
   my $relation_classifications;
   if (ref($attrs->{from}) eq 'ARRAY') {
-    $attrs->{from} = $storage->_prune_unused_joins ($attrs->{from}, $attrs->{select}, $cond, $attrs);
-
-    $relation_classifications = $storage->_resolve_aliastypes_from_select_args (
-      [ @{$attrs->{from}}[1 .. $#{$attrs->{from}}] ],
-      $attrs->{select},
-      $cond,
-      $attrs
-    ) unless $needs_group_by_subq;  # we already know we need a group, no point of resolving them
+    if (@{$attrs->{from}} == 1) {
+      # not a fucking JOIN at all, quit with the dickery
+      $relation_classifications = {};
+    } else {
+      $attrs->{from} = $storage->_prune_unused_joins ($attrs->{from}, $attrs->{select}, $cond, $attrs);
+
+      $relation_classifications = $storage->_resolve_aliastypes_from_select_args (
+        [ @{$attrs->{from}}[1 .. $#{$attrs->{from}}] ],
+        $attrs->{select},
+        $cond,
+        $attrs
+      ) unless $needs_group_by_subq;  # we already know we need a group, no point of resolving them
+    }
   }
   else {
     $needs_group_by_subq ||= 1; # if {from} is unparseable assume the worst
@@ -2006,21 +1786,13 @@ sub _rs_update_delete {
   ) {
     # Most databases do not allow aliasing of tables in UPDATE/DELETE. Thus
     # a condition containing 'me' or other table prefixes will not work
-    # at all. What this code tries to do (badly) is to generate a condition
-    # with the qualifiers removed, by exploiting the quote mechanism of sqla
-    #
-    # this is atrocious and should be replaced by normal sqla introspection
-    # one sunny day
-    my ($sql, @bind) = do {
-      my $sqla = $rsrc->storage->sql_maker;
-      local $sqla->{_dequalify_idents} = 1;
-      $sqla->_recurse_where($self->{cond});
-    } if $self->{cond};
-
+    # at all. Tell SQLMaker to dequalify idents via a gross hack.
+    my $sqla = $rsrc->storage->sql_maker;
+    local $sqla->{_dequalify_idents} = 1;
     return $rsrc->storage->$op(
       $rsrc,
       $op eq 'update' ? $values : (),
-      $self->{cond} ? \[$sql, @bind] : (),
+      $self->{cond},
     );
   }
 
@@ -3660,17 +3432,15 @@ sub _resolved_attrs {
     }
   }
 
-  # generate selections based on the prefetch helper
-  my $prefetch;
-  $prefetch = $self->_merge_joinpref_attr( {}, delete $attrs->{prefetch} )
-    if defined $attrs->{prefetch};
-
-  if ($prefetch) {
+  $attrs->{collapse} ||= {};
+  if ($attrs->{prefetch}) {
 
     $self->throw_exception("Unable to prefetch, resultset contains an unnamed selector $attrs->{_dark_selector}{string}")
       if $attrs->{_dark_selector};
 
-    $attrs->{collapse} = 1;
+    my $prefetch = $self->_merge_joinpref_attr( {}, delete $attrs->{prefetch} );
+
+    my $prefetch_ordering = [];
 
     # this is a separate structure (we don't look in {from} directly)
     # as the resolver needs to shift things off the lists to work
@@ -3693,7 +3463,8 @@ sub _resolved_attrs {
       }
     }
 
-    my @prefetch = $source->_resolve_prefetch( $prefetch, $alias, $join_map );
+    my @prefetch =
+      $source->_resolve_prefetch( $prefetch, $alias, $join_map, $prefetch_ordering, $attrs->{collapse} );
 
     # we need to somehow mark which columns came from prefetch
     if (@prefetch) {
@@ -3703,34 +3474,11 @@ sub _resolved_attrs {
 
     push @{ $attrs->{select} }, (map { $_->[0] } @prefetch);
     push @{ $attrs->{as} }, (map { $_->[1] } @prefetch);
-  }
-
-  # run through the resulting joinstructure (starting from our current slot)
-  # and unset collapse if proven unnesessary
-  if ($attrs->{collapse} && ref $attrs->{from} eq 'ARRAY') {
-
-    if (@{$attrs->{from}} > 1) {
-
-      # find where our table-spec starts and consider only things after us
-      my @fromlist = @{$attrs->{from}};
-      while (@fromlist) {
-        my $t = shift @fromlist;
-        $t = $t->[0] if ref $t eq 'ARRAY';  #me vs join from-spec mismatch
-        last if ($t->{-alias} && $t->{-alias} eq $alias);
-      }
 
-      for (@fromlist) {
-        $attrs->{collapse} = ! $_->[0]{-is_single}
-          and last;
-      }
-    }
-    else {
-      # no joins - no collapse
-      $attrs->{collapse} = 0;
-    }
+    push( @{$attrs->{order_by}}, @$prefetch_ordering );
+    $attrs->{_collapse_order_by} = \@$prefetch_ordering;
   }
 
-
   # if both page and offset are specified, produce a combined offset
   # even though it doesn't make much sense, this is what pre 081xx has
   # been doing