Add undocumented ability to disable the join optimizer

[dbsrgits/DBIx-Class.git] / lib / DBIx / Class / Storage / DBIHacks.pm

diff --git a/lib/DBIx/Class/Storage/DBIHacks.pm b/lib/DBIx/Class/Storage/DBIHacks.pm
index 23b528b..240fa3c 100644 (file)
--- a/lib/DBIx/Class/Storage/DBIHacks.pm
+++ b/lib/DBIx/Class/Storage/DBIHacks.pm
@@ -23,10 +23,11 @@ use namespace::clean;
 # {from} specs, aiding the RDBMS query optimizer
 #
 sub _prune_unused_joins {
-  my ($self) = shift;
-
+  my $self = shift;
   my ($from, $select, $where, $attrs) = @_;
 
+  return $from unless $self->_use_join_optimizer;
+
   if (ref $from ne 'ARRAY' || ref $from->[0] ne 'HASH' || ref $from->[1] ne 'ARRAY') {
     return $from;   # only standard {from} specs are supported
   }
@@ -37,7 +38,6 @@ sub _prune_unused_joins {
   # {multiplying} joins can go
   delete $aliastypes->{multiplying} if $attrs->{group_by};
 
-
   my @newfrom = $from->[0]; # FROM head is always present
 
   my %need_joins = (map { %{$_||{}} } (values %$aliastypes) );
@@ -101,27 +101,41 @@ sub _adjust_select_args_for_complex_prefetch {
     push @{$inner_attrs->{as}}, $attrs->{as}[$i];
   }
 
-  # construct the inner $from for the subquery
+  # construct the inner $from and lock it in a subquery
   # we need to prune first, because this will determine if we need a group_by below
-  my $inner_from = $self->_prune_unused_joins ($from, $inner_select, $where, $inner_attrs);
-
-  # if a multi-type join was needed in the subquery - add a group_by to simulate the
-  # collapse in the subq
-  $inner_attrs->{group_by} ||= $inner_select
-    if first { ! $_->[0]{-is_single} } (@{$inner_from}[1 .. $#$inner_from]);
-
-  # generate the subquery
-  my $subq = $self->_select_args_to_query (
-    $inner_from,
-    $inner_select,
-    $where,
-    $inner_attrs,
-  );
+  # the fake group_by is so that the pruner throws away all non-selecting, non-restricting
+  # multijoins (since we def. do not care about those inside the subquery)
+
+  my $subq_joinspec = do {
+
+    # must use it here regardless of user requests
+    local $self->{_use_join_optimizer} = 1;
+
+    my $inner_from = $self->_prune_unused_joins ($from, $inner_select, $where, {
+      group_by => ['dummy'], %$inner_attrs,
+    });
+
+    # if a multi-type join was needed in the subquery - add a group_by to simulate the
+    # collapse in the subq
+    $inner_attrs->{group_by} ||= $inner_select
+      if first { ! $_->[0]{-is_single} } (@{$inner_from}[1 .. $#$inner_from]);
+
+    # we already optimized $inner_from above
+    local $self->{_use_join_optimizer} = 0;
 
-  my $subq_joinspec = {
-    -alias => $attrs->{alias},
-    -source_handle => $inner_from->[0]{-source_handle},
-    $attrs->{alias} => $subq,
+    # generate the subquery
+    my $subq = $self->_select_args_to_query (
+      $inner_from,
+      $inner_select,
+      $where,
+      $inner_attrs,
+    );
+
+    +{
+      -alias => $attrs->{alias},
+      -source_handle => $inner_from->[0]{-source_handle},
+      $attrs->{alias} => $subq,
+    };
   };
 
   # Generate the outer from - this is relatively easy (really just replace
@@ -134,14 +148,13 @@ sub _adjust_select_args_for_complex_prefetch {
   # - it is part of the restrictions, in which case we need to collapse the outer
   #   result by tackling yet another group_by to the outside of the query
 
-  # normalize a copy of $from, so it will be easier to work with further
-  # down (i.e. promote the initial hashref to an AoH)
   $from = [ @$from ];
-  $from->[0] = [ $from->[0] ];
 
   # so first generate the outer_from, up to the substitution point
   my @outer_from;
   while (my $j = shift @$from) {
+    $j = [ $j ] unless ref $j eq 'ARRAY'; # promote the head-from to an AoH
+
     if ($j->[0]{-alias} eq $attrs->{alias}) { # time to swap
       push @outer_from, [
         $subq_joinspec,
@@ -154,7 +167,7 @@ sub _adjust_select_args_for_complex_prefetch {
     }
   }
 
-  # scan the from spec against different attributes, and see which joins are needed
+  # scan the *remaining* from spec against different attributes, and see which joins are needed
   # in what role
   my $outer_aliastypes =
     $self->_resolve_aliastypes_from_select_args( $from, $outer_select, $where, $outer_attrs );
@@ -218,7 +231,7 @@ sub _resolve_aliastypes_from_select_args {
 
     $alias_list->{$al} = $j;
     $aliases_by_type->{multiplying}{$al} = 1
-      unless $j->{-is_single};
+      if ref($_) eq 'ARRAY' and ! $j->{-is_single}; # not array == {from} head == can't be multiplying
   }
 
   # get a column to source/alias map (including unqualified ones)
@@ -245,7 +258,6 @@ sub _resolve_aliastypes_from_select_args {
 
   my ($lquote, $rquote, $sep) = map { quotemeta $_ } ($sql_maker->_quote_chars, $sql_maker->name_sep);
 
-
   # generate sql chunks
   my $to_scan = {
     restricting => [
@@ -303,10 +315,10 @@ sub _resolve_aliastypes_from_select_args {
     );
   }
 
-  # mark all join parents as mentioned
+  # mark all restricting/selecting join parents as such
   # (e.g.  join => { cds => 'tracks' } - tracks will need to bring cds too )
-  for my $type (keys %$aliases_by_type) {
-    for my $alias (keys %{$aliases_by_type->{$type}}) {
+  for my $type (qw/restricting selecting/) {
+    for my $alias (keys %{$aliases_by_type->{$type}||{}}) {
       $aliases_by_type->{$type}{$_} = 1
         for (map { values %$_ } @{ $alias_list->{$alias}{-join_path} || [] });
     }
@@ -519,8 +531,13 @@ sub _strip_cond_qualifiers {
     }
     else {
       foreach my $key (keys %$where) {
-        $key =~ /([^.]+)$/;
-        $cond->{$1} = $where->{$key};
+        if ($key eq '-or' && ref $where->{$key} eq 'ARRAY') {
+          $cond->{$key} = $self->_strip_cond_qualifiers($where->{$key});
+        }
+        else {
+          $key =~ /([^.]+)$/;
+          $cond->{$1} = $where->{$key};
+        }
       }
     }
   }