From: Peter Rabbitson <ribasushi@cpan.org>
Date: Wed, 20 May 2015 13:25:06 +0000 (+0200)
Subject: Replace all instances of ; in the rowparser loop with , ( ~15% speedup )
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=05a5ca4b941f0741e91d0972334ab96b96e13f4d;p=dbsrgits%2FDBIx-Class.git

Replace all instances of ; in the rowparser loop with , ( ~15% speedup )

The functional diff best examined via `... --color-words -w lib ...`

This is another microoptimization, which is nevertheless measurable on 1000+
row resultsets. Investigation into this was prompted by a curious comment made
by bulk88[1] in response to xdg[2]:

  Every ";" is an op that executes that adjusts current line number

Given that we already generate all this code, and it is not intended to be
read by a human, swapping ; with , is only logical. A (very very crude) check
with the included benchmarker indeed shows a repeatable difference on 5.16.2

[1] http://www.nntp.perl.org/group/perl.perl5.porters/2015/05/msg228074.html
[2] http://www.nntp.perl.org/group/perl.perl5.porters/2015/05/msg228068.html
---

diff --git a/examples/Benchmarks/semicolon_vs_comma_rowparser/comma.src b/examples/Benchmarks/semicolon_vs_comma_rowparser/comma.src
new file mode 100644
index 0000000..95d4f96
--- /dev/null
+++ b/examples/Benchmarks/semicolon_vs_comma_rowparser/comma.src
@@ -0,0 +1,83 @@
+### BEGIN LITERAL STRING EVAL
+  my $rows_pos = 0;
+  my ($result_pos, @collapse_idx, $cur_row_data, %cur_row_ids );
+
+  # this loop is a bit arcane - the rationale is that the passed in
+  # $_[0] will either have only one row (->next) or will have all
+  # rows already pulled in (->all and/or unordered). Given that the
+  # result can be rather large - we reuse the same already allocated
+  # array, since the collapsed prefetch is smaller by definition.
+  # At the end we cut the leftovers away and move on.
+  while ($cur_row_data = (
+    (
+      $rows_pos >= 0
+        and
+      (
+        $_[0][$rows_pos++]
+          or
+        # It may be tempting to drop the -1 and undef $rows_pos instead
+        # thus saving the >= comparison above as well
+        # However NULL-handlers and underdefined root markers both use
+        # $rows_pos as a last-resort-uniqueness marker (it either is
+        # monotonically increasing while we parse ->all, or is set at
+        # a steady -1 when we are dealing with a single root node). For
+        # the time being the complication of changing all callsites seems
+        # overkill, for what is going to be a very modest saving of ops
+        ( ($rows_pos = -1), undef )
+      )
+    )
+      or
+    ( $_[1] and $_[1]->() )
+  ) ) {
+
+    # the undef checks may or may not be there
+    # depending on whether we prune or not
+    #
+    # due to left joins some of the ids may be NULL/undef, and
+    # won't play well when used as hash lookups
+    # we also need to differentiate NULLs on per-row/per-col basis
+    # (otherwise folding of optional 1:1s will be greatly confused
+( @cur_row_ids{( 0, 1, 5, 6, 8, 10 )} = (
+@{$cur_row_data}[( 0, 1, 5, 6, 8, 10 )]
+ ) ),
+
+    # in the case of an underdefined root - calculate the virtual id (otherwise no code at all)
+
+
+    # if we were supplied a coderef - we are collapsing lazily (the set
+    # is ordered properly)
+    # as long as we have a result already and the next result is new we
+    # return the pre-read data and bail
+( $_[1] and $result_pos and ! $collapse_idx[0]{ $cur_row_ids{1} } and (unshift @{$_[2]}, $cur_row_data) and last ),
+
+    # the rel assemblers
+( $collapse_idx[0]{ $cur_row_ids{1} } //= $_[0][$result_pos++] = [ { "genreid" => $cur_row_data->[4], "latest_cd" => $cur_row_data->[7], "year" => $cur_row_data->[3] } ] ),
+( $collapse_idx[0]{ $cur_row_ids{1} }[1]{"existing_single_track"} //= $collapse_idx[1]{ $cur_row_ids{1} } = [  ] ),
+( $collapse_idx[1]{ $cur_row_ids{1} }[1]{"cd"} //= $collapse_idx[2]{ $cur_row_ids{1} } = [  ] ),
+( $collapse_idx[2]{ $cur_row_ids{1} }[1]{"artist"} //= $collapse_idx[3]{ $cur_row_ids{1} } = [ { "artistid" => $cur_row_data->[1] } ] ),
+( ( ! defined $cur_row_data->[6] )
+  ? $collapse_idx[3]{ $cur_row_ids{1} }[1]{"cds"} = []
+  : do {
+( (! $collapse_idx[4]{ $cur_row_ids{1} }{ $cur_row_ids{6} }) and push @{$collapse_idx[3]{ $cur_row_ids{1} }[1]{"cds"}}, $collapse_idx[4]{ $cur_row_ids{1} }{ $cur_row_ids{6} } = [ { "cdid" => $cur_row_data->[6], "genreid" => $cur_row_data->[9], "year" => $cur_row_data->[2] } ] ),
+( ( ! defined $cur_row_data->[8] )
+  ? $collapse_idx[4]{ $cur_row_ids{1} }{ $cur_row_ids{6} }[1]{"tracks"} = []
+  : do {
+( (! $collapse_idx[5]{ $cur_row_ids{1} }{ $cur_row_ids{6} }{ $cur_row_ids{8} }) and push @{$collapse_idx[4]{ $cur_row_ids{1} }{ $cur_row_ids{6} }[1]{"tracks"}}, $collapse_idx[5]{ $cur_row_ids{1} }{ $cur_row_ids{6} }{ $cur_row_ids{8} } = [ { "title" => $cur_row_data->[8] } ] ),
+} ),
+} ),
+( ( ! defined $cur_row_data->[5] )
+  ? $collapse_idx[0]{ $cur_row_ids{1} }[1]{"tracks"} = []
+  : do {
+( (! $collapse_idx[6]{ $cur_row_ids{1} }{ $cur_row_ids{5} }) and push @{$collapse_idx[0]{ $cur_row_ids{1} }[1]{"tracks"}}, $collapse_idx[6]{ $cur_row_ids{1} }{ $cur_row_ids{5} } = [ { "title" => $cur_row_data->[5] } ] ),
+( ( ! defined $cur_row_data->[10] )
+  ? $collapse_idx[6]{ $cur_row_ids{1} }{ $cur_row_ids{5} }[1]{"lyrics"} = []
+  : do {
+( $collapse_idx[6]{ $cur_row_ids{1} }{ $cur_row_ids{5} }[1]{"lyrics"} //= $collapse_idx[7]{ $cur_row_ids{1} }{ $cur_row_ids{5} }{ $cur_row_ids{10} } = [  ] ),
+( (! $collapse_idx[8]{ $cur_row_ids{0} }{ $cur_row_ids{1} }{ $cur_row_ids{5} }{ $cur_row_ids{10} }) and push @{$collapse_idx[7]{ $cur_row_ids{1} }{ $cur_row_ids{5} }{ $cur_row_ids{10} }[1]{"existing_lyric_versions"}}, $collapse_idx[8]{ $cur_row_ids{0} }{ $cur_row_ids{1} }{ $cur_row_ids{5} }{ $cur_row_ids{10} } = [ { "lyric_id" => $cur_row_data->[10], "text" => $cur_row_data->[0] } ] ),
+} ),
+} ),
+
+  }
+
+  $#{$_[0]} = $result_pos - 1; # truncate the passed in array to where we filled it with results
+### END LITERAL STRING EVAL
diff --git a/examples/Benchmarks/semicolon_vs_comma_rowparser/semicol.src b/examples/Benchmarks/semicolon_vs_comma_rowparser/semicol.src
new file mode 100644
index 0000000..3d33e96
--- /dev/null
+++ b/examples/Benchmarks/semicolon_vs_comma_rowparser/semicol.src
@@ -0,0 +1,83 @@
+### BEGIN LITERAL STRING EVAL
+  my $rows_pos = 0;
+  my ($result_pos, @collapse_idx, $cur_row_data, %cur_row_ids );
+
+  # this loop is a bit arcane - the rationale is that the passed in
+  # $_[0] will either have only one row (->next) or will have all
+  # rows already pulled in (->all and/or unordered). Given that the
+  # result can be rather large - we reuse the same already allocated
+  # array, since the collapsed prefetch is smaller by definition.
+  # At the end we cut the leftovers away and move on.
+  while ($cur_row_data = (
+    (
+      $rows_pos >= 0
+        and
+      (
+        $_[0][$rows_pos++]
+          or
+        # It may be tempting to drop the -1 and undef $rows_pos instead
+        # thus saving the >= comparison above as well
+        # However NULL-handlers and underdefined root markers both use
+        # $rows_pos as a last-resort-uniqueness marker (it either is
+        # monotonically increasing while we parse ->all, or is set at
+        # a steady -1 when we are dealing with a single root node). For
+        # the time being the complication of changing all callsites seems
+        # overkill, for what is going to be a very modest saving of ops
+        ( ($rows_pos = -1), undef )
+      )
+    )
+      or
+    ( $_[1] and $_[1]->() )
+  ) ) {
+
+    # the undef checks may or may not be there
+    # depending on whether we prune or not
+    #
+    # due to left joins some of the ids may be NULL/undef, and
+    # won't play well when used as hash lookups
+    # we also need to differentiate NULLs on per-row/per-col basis
+    # (otherwise folding of optional 1:1s will be greatly confused
+@cur_row_ids{( 0, 1, 5, 6, 8, 10 )} = (
+@{$cur_row_data}[( 0, 1, 5, 6, 8, 10 )]
+ );
+
+    # in the case of an underdefined root - calculate the virtual id (otherwise no code at all)
+
+
+    # if we were supplied a coderef - we are collapsing lazily (the set
+    # is ordered properly)
+    # as long as we have a result already and the next result is new we
+    # return the pre-read data and bail
+$_[1] and $result_pos and ! $collapse_idx[0]{ $cur_row_ids{1} } and (unshift @{$_[2]}, $cur_row_data) and last;
+
+    # the rel assemblers
+$collapse_idx[0]{ $cur_row_ids{1} } //= $_[0][$result_pos++] = [ { "genreid" => $cur_row_data->[4], "latest_cd" => $cur_row_data->[7], "year" => $cur_row_data->[3] } ];
+$collapse_idx[0]{ $cur_row_ids{1} }[1]{"existing_single_track"} //= $collapse_idx[1]{ $cur_row_ids{1} } = [  ];
+$collapse_idx[1]{ $cur_row_ids{1} }[1]{"cd"} //= $collapse_idx[2]{ $cur_row_ids{1} } = [  ];
+$collapse_idx[2]{ $cur_row_ids{1} }[1]{"artist"} //= $collapse_idx[3]{ $cur_row_ids{1} } = [ { "artistid" => $cur_row_data->[1] } ];
+( ! defined $cur_row_data->[6] )
+  ? $collapse_idx[3]{ $cur_row_ids{1} }[1]{"cds"} = []
+  : do {
+(! $collapse_idx[4]{ $cur_row_ids{1} }{ $cur_row_ids{6} }) and push @{$collapse_idx[3]{ $cur_row_ids{1} }[1]{"cds"}}, $collapse_idx[4]{ $cur_row_ids{1} }{ $cur_row_ids{6} } = [ { "cdid" => $cur_row_data->[6], "genreid" => $cur_row_data->[9], "year" => $cur_row_data->[2] } ];
+( ! defined $cur_row_data->[8] )
+  ? $collapse_idx[4]{ $cur_row_ids{1} }{ $cur_row_ids{6} }[1]{"tracks"} = []
+  : do {
+(! $collapse_idx[5]{ $cur_row_ids{1} }{ $cur_row_ids{6} }{ $cur_row_ids{8} }) and push @{$collapse_idx[4]{ $cur_row_ids{1} }{ $cur_row_ids{6} }[1]{"tracks"}}, $collapse_idx[5]{ $cur_row_ids{1} }{ $cur_row_ids{6} }{ $cur_row_ids{8} } = [ { "title" => $cur_row_data->[8] } ];
+};
+};
+( ! defined $cur_row_data->[5] )
+  ? $collapse_idx[0]{ $cur_row_ids{1} }[1]{"tracks"} = []
+  : do {
+(! $collapse_idx[6]{ $cur_row_ids{1} }{ $cur_row_ids{5} }) and push @{$collapse_idx[0]{ $cur_row_ids{1} }[1]{"tracks"}}, $collapse_idx[6]{ $cur_row_ids{1} }{ $cur_row_ids{5} } = [ { "title" => $cur_row_data->[5] } ];
+( ! defined $cur_row_data->[10] )
+  ? $collapse_idx[6]{ $cur_row_ids{1} }{ $cur_row_ids{5} }[1]{"lyrics"} = []
+  : do {
+$collapse_idx[6]{ $cur_row_ids{1} }{ $cur_row_ids{5} }[1]{"lyrics"} //= $collapse_idx[7]{ $cur_row_ids{1} }{ $cur_row_ids{5} }{ $cur_row_ids{10} } = [  ];
+(! $collapse_idx[8]{ $cur_row_ids{0} }{ $cur_row_ids{1} }{ $cur_row_ids{5} }{ $cur_row_ids{10} }) and push @{$collapse_idx[7]{ $cur_row_ids{1} }{ $cur_row_ids{5} }{ $cur_row_ids{10} }[1]{"existing_lyric_versions"}}, $collapse_idx[8]{ $cur_row_ids{0} }{ $cur_row_ids{1} }{ $cur_row_ids{5} }{ $cur_row_ids{10} } = [ { "lyric_id" => $cur_row_data->[10], "text" => $cur_row_data->[0] } ];
+};
+};
+
+  }
+
+  $#{$_[0]} = $result_pos - 1; # truncate the passed in array to where we filled it with results
+### END LITERAL STRING EVAL
diff --git a/examples/Benchmarks/semicolon_vs_comma_rowparser/sloppy_bench.pl b/examples/Benchmarks/semicolon_vs_comma_rowparser/sloppy_bench.pl
new file mode 100644
index 0000000..fb12fb8
--- /dev/null
+++ b/examples/Benchmarks/semicolon_vs_comma_rowparser/sloppy_bench.pl
@@ -0,0 +1,28 @@
+use warnings;
+use strict;
+
+use Benchmark qw( cmpthese :hireswallclock);
+use Sereal;
+use Devel::Dwarn;
+
+my ($semicol, $comma) = map {
+  my $src = do { local (@ARGV, $/) = $_; <> };
+  eval "sub { use strict; use warnings; use warnings FATAL => 'uninitialized'; $src }" or die $@;
+} qw( semicol.src comma.src );
+
+my $enc = Sereal::Encoder->new;
+my $dec = Sereal::Decoder->new;
+
+for my $iters ( 100, 10_000, 100_000 ) {
+  my $dataset = [];
+  push @$dataset, [ (scalar @$dataset) x 11 ]
+    while @$dataset < $iters;
+
+  my $ice = $enc->encode($dataset);
+
+  print "\nTiming $iters 'rows'...\n";
+  cmpthese( -10, {
+    semicol => sub { $semicol->($dec->decode($ice)) },
+    comma => sub { $comma->($dec->decode($ice)) },
+  })
+}
diff --git a/lib/DBIx/Class/ResultSource/RowParser/Util.pm b/lib/DBIx/Class/ResultSource/RowParser/Util.pm
index cb760ff..6ef7589 100644
--- a/lib/DBIx/Class/ResultSource/RowParser/Util.pm
+++ b/lib/DBIx/Class/ResultSource/RowParser/Util.pm
@@ -133,7 +133,7 @@ sub assemble_collapsing_parser {
 
     $top_node_key = "{ \$cur_row_ids{$virtual_column_idx} }";
 
-    $top_node_key_assembler = sprintf " \$cur_row_ids{%d} = ( %s ); ",
+    $top_node_key_assembler = sprintf "( \$cur_row_ids{%d} = (%s) ),",
       $virtual_column_idx,
       "\n" . join( "\n  or\n", @path_parts, qq{"\0\$rows_pos\0"} )
     ;
@@ -155,16 +155,16 @@ sub assemble_collapsing_parser {
     %{ $stats->{idcols_seen} },
   } };
 
-  my $row_id_defs = sprintf "\@cur_row_ids{( %s )} = ( \n%s \n );",
+  my $row_id_defs = sprintf "( \@cur_row_ids{( %s )} = (\n%s\n ) ),",
     join (', ', @row_ids ),
     # in case we prune - we will never hit undefs/NULLs as pigeon-hole-criteria
     ( $args->{prune_null_branches}
       ? sprintf( '@{$cur_row_data}[( %s )]', join ', ', @row_ids )
       : join (",\n", map {
-        my $quoted_null_val = qq( "\0NULL\xFF\${rows_pos}\xFF${_}\0" );
+        my $quoted_null_val = qq("\0NULL\xFF\${rows_pos}\xFF${_}\0");
         HAS_DOR
-          ? qq! ( \$cur_row_data->[$_] // $quoted_null_val ) !
-          : qq! ( defined(\$cur_row_data->[$_]) ? \$cur_row_data->[$_] : $quoted_null_val ) !
+          ? qq!( \$cur_row_data->[$_] // $quoted_null_val )!
+          : qq!( defined(\$cur_row_data->[$_]) ? \$cur_row_data->[$_] : $quoted_null_val )!
       } @row_ids)
     )
   ;
@@ -218,7 +218,7 @@ sub assemble_collapsing_parser {
     # is ordered properly)
     # as long as we have a result already and the next result is new we
     # return the pre-read data and bail
-$_[1] and $result_pos and ! $collapse_idx[0]%3$s and (unshift @{$_[2]}, $cur_row_data) and last;
+( $_[1] and $result_pos and ! $collapse_idx[0]%3$s and (unshift @{$_[2]}, $cur_row_data) and last ),
 
     # the rel assemblers
 %4$s
@@ -271,7 +271,7 @@ sub __visit_infmap_collapse {
   my @src;
 
   if ($cur_node_idx == 0) {
-    push @src, sprintf( '%s %s $_[0][$result_pos++] = %s;',
+    push @src, sprintf( '( %s %s $_[0][$result_pos++] = %s ),',
       $node_idx_slot,
       (HAS_DOR ? '//=' : '||='),
       $me_struct || '{}',
@@ -285,7 +285,7 @@ sub __visit_infmap_collapse {
     );
 
     if ($args->{collapse_map}->{-is_single}) {
-      push @src, sprintf ( '%s %s %s%s;',
+      push @src, sprintf ( '( %s %s %s%s ),',
         $parent_attach_slot,
         (HAS_DOR ? '//=' : '||='),
         $node_idx_slot,
@@ -293,7 +293,7 @@ sub __visit_infmap_collapse {
       );
     }
     else {
-      push @src, sprintf('(! %s) and push @{%s}, %s%s;',
+      push @src, sprintf('( (! %s) and push @{%s}, %s%s ),',
         $node_idx_slot,
         $parent_attach_slot,
         $node_idx_slot,
@@ -332,7 +332,7 @@ sub __visit_infmap_collapse {
       if ($args->{prune_null_branches}) {
 
         # start of wrap of the entire chain in a conditional
-        splice @src, $rel_src_pos, 0, sprintf "( ! defined %s )\n  ? %s%s{%s} = %s\n  : do {",
+        splice @src, $rel_src_pos, 0, sprintf "( ( ! defined %s )\n  ? %s%s{%s} = %s\n  : do {",
           "\$cur_row_data->[$first_distinct_child_idcol]",
           $node_idx_slot,
           $args->{hri_style} ? '' : '[1]',
@@ -341,11 +341,11 @@ sub __visit_infmap_collapse {
         ;
 
         # end of wrap
-        push @src, '};'
+        push @src, '} ),'
       }
       else {
 
-        splice @src, $rel_src_pos + 1, 0, sprintf ( '(defined %s) or bless (%s[1]{%s}, %s);',
+        splice @src, $rel_src_pos + 1, 0, sprintf ( '( (defined %s) or bless (%s[1]{%s}, %s) ),',
           "\$cur_row_data->[$first_distinct_child_idcol]",
           $node_idx_slot,
           perlstring($rel),
diff --git a/t/resultset/rowparser_internals.t b/t/resultset/rowparser_internals.t
index 646ead0..5818248 100644
--- a/t/resultset/rowparser_internals.t
+++ b/t/resultset/rowparser_internals.t
@@ -265,45 +265,49 @@ is_same_src (
       ( $_[1] and $_[1]->() )
     ) ) {
 
-      @cur_row_ids{0,1,3,4,5} = (
+      ( @cur_row_ids{0,1,3,4,5} = (
         ( $cur_row_data->[0] // "\0NULL\xFF$rows_pos\xFF0\0" ),
         ( $cur_row_data->[1] // "\0NULL\xFF$rows_pos\xFF1\0" ),
         ( $cur_row_data->[3] // "\0NULL\xFF$rows_pos\xFF3\0" ),
         ( $cur_row_data->[4] // "\0NULL\xFF$rows_pos\xFF4\0" ),
         ( $cur_row_data->[5] // "\0NULL\xFF$rows_pos\xFF5\0" ),
-      );
+      ) ),
 
       # a present cref in $_[1] implies lazy prefetch, implies a supplied stash in $_[2]
-      $_[1] and $result_pos and ! $collapse_idx[0]{$cur_row_ids{4}}{$cur_row_ids{5}} and (unshift @{$_[2]}, $cur_row_data) and last;
+      ( $_[1] and $result_pos and ! $collapse_idx[0]{$cur_row_ids{4}}{$cur_row_ids{5}} and (unshift @{$_[2]}, $cur_row_data) and last ),
 
       # the rowdata itself for root node
-      $collapse_idx[0]{$cur_row_ids{4}}{$cur_row_ids{5}} //= $_[0][$result_pos++] = [{ artist => $cur_row_data->[5], title => $cur_row_data->[4], year => $cur_row_data->[2] }];
+      ( $collapse_idx[0]{$cur_row_ids{4}}{$cur_row_ids{5}} //= $_[0][$result_pos++] = [{ artist => $cur_row_data->[5], title => $cur_row_data->[4], year => $cur_row_data->[2] }] ),
 
       # prefetch data of single_track (placed in root)
-      $collapse_idx[0]{$cur_row_ids{4}}{$cur_row_ids{5}}[1]{single_track} //= $collapse_idx[1]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}} = [];
-      defined($cur_row_data->[1]) or bless( $collapse_idx[0]{$cur_row_ids{4}}{$cur_row_ids{5}}[1]{single_track}, __NBC__ );
+      ( $collapse_idx[0]{$cur_row_ids{4}}{$cur_row_ids{5}}[1]{single_track} //= $collapse_idx[1]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}} = [] ),
+      ( defined($cur_row_data->[1]) or bless( $collapse_idx[0]{$cur_row_ids{4}}{$cur_row_ids{5}}[1]{single_track}, __NBC__ ) ),
 
       # prefetch data of cd (placed in single_track)
-      $collapse_idx[1]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}}[1]{cd} //= $collapse_idx[2]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}} = [];
+      ( $collapse_idx[1]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}}[1]{cd} //= $collapse_idx[2]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}} = [] ),
 
       # prefetch data of artist ( placed in single_track->cd)
-      $collapse_idx[2]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}}[1]{artist} //= $collapse_idx[3]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}} = [{ artistid => $cur_row_data->[1] }];
+      ( $collapse_idx[2]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}}[1]{artist} //= $collapse_idx[3]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}} = [{ artistid => $cur_row_data->[1] }] ),
 
       # prefetch data of cds (if available)
-      (! $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}} )
-        and
-      push @{$collapse_idx[3]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}}[1]{cds}}, (
-        $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}} = [{ cdid => $cur_row_data->[3] }]
-      );
-      defined($cur_row_data->[3]) or bless( $collapse_idx[3]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}}[1]{cds}, __NBC__ );
+      (
+        (! $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}} )
+          and
+        push @{$collapse_idx[3]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}}[1]{cds}}, (
+          $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}} = [{ cdid => $cur_row_data->[3] }]
+        )
+      ),
+      ( defined($cur_row_data->[3]) or bless( $collapse_idx[3]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}}[1]{cds}, __NBC__ ) ),
 
       # prefetch data of tracks (if available)
-      (! $collapse_idx[5]{$cur_row_ids{0}}{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}} )
-        and
-      push @{$collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}}[1]{tracks}}, (
-        $collapse_idx[5]{$cur_row_ids{0}}{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}} = [{ title => $cur_row_data->[0] }]
-      );
-      defined($cur_row_data->[0]) or bless( $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}}[1]{tracks}, __NBC__ );
+      (
+        (! $collapse_idx[5]{$cur_row_ids{0}}{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}} )
+          and
+        push @{$collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}}[1]{tracks}}, (
+          $collapse_idx[5]{$cur_row_ids{0}}{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}} = [{ title => $cur_row_data->[0] }]
+        )
+      ),
+      ( defined($cur_row_data->[0]) or bless( $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}}[1]{tracks}, __NBC__ ) ),
 
     }
     $#{$_[0]} = $result_pos - 1;
@@ -335,44 +339,48 @@ is_same_src (
       ( $_[1] and $_[1]->() )
     ) ) {
 
-      @cur_row_ids{0, 1, 3, 4, 5} = @{$cur_row_data}[0, 1, 3, 4, 5];
+      ( @cur_row_ids{0, 1, 3, 4, 5} = @{$cur_row_data}[0, 1, 3, 4, 5] ),
 
       # a present cref in $_[1] implies lazy prefetch, implies a supplied stash in $_[2]
-      $_[1] and $result_pos and ! $collapse_idx[0]{$cur_row_ids{4}}{$cur_row_ids{5}} and (unshift @{$_[2]}, $cur_row_data) and last;
+      ( $_[1] and $result_pos and ! $collapse_idx[0]{$cur_row_ids{4}}{$cur_row_ids{5}} and (unshift @{$_[2]}, $cur_row_data) and last ),
 
       # the rowdata itself for root node
-      $collapse_idx[0]{$cur_row_ids{4}}{$cur_row_ids{5}} //= $_[0][$result_pos++] = { artist => $cur_row_data->[5], title => $cur_row_data->[4], year => $cur_row_data->[2] };
+      ( $collapse_idx[0]{$cur_row_ids{4}}{$cur_row_ids{5}} //= $_[0][$result_pos++] = { artist => $cur_row_data->[5], title => $cur_row_data->[4], year => $cur_row_data->[2] } ),
 
       # prefetch data of single_track (placed in root)
-      (! defined($cur_row_data->[1]) ) ? $collapse_idx[0]{$cur_row_ids{4}}{$cur_row_ids{5}}{single_track} = undef : do {
-        $collapse_idx[0]{$cur_row_ids{4}}{$cur_row_ids{5}}{single_track} //= $collapse_idx[1]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}};
+      ( (! defined($cur_row_data->[1]) ) ? $collapse_idx[0]{$cur_row_ids{4}}{$cur_row_ids{5}}{single_track} = undef : do {
+        ( $collapse_idx[0]{$cur_row_ids{4}}{$cur_row_ids{5}}{single_track} //= $collapse_idx[1]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}} ),
 
         # prefetch data of cd (placed in single_track)
-        $collapse_idx[1]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}}{cd} //= $collapse_idx[2]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}};
+        ( $collapse_idx[1]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}}{cd} //= $collapse_idx[2]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}} ),
 
         # prefetch data of artist ( placed in single_track->cd)
-        $collapse_idx[2]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}}{artist} //= $collapse_idx[3]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}} = { artistid => $cur_row_data->[1] };
+        ( $collapse_idx[2]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}}{artist} //= $collapse_idx[3]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}} = { artistid => $cur_row_data->[1] } ),
 
         # prefetch data of cds (if available)
-        (! defined $cur_row_data->[3] ) ? $collapse_idx[3]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}}{cds} = [] : do {
+        ( (! defined $cur_row_data->[3] ) ? $collapse_idx[3]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}}{cds} = [] : do {
 
-          (! $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}} )
-            and
-          push @{$collapse_idx[3]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}}{cds}}, (
-            $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}} = { cdid => $cur_row_data->[3] }
-          );
+          (
+            (! $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}} )
+              and
+            push @{$collapse_idx[3]{$cur_row_ids{1}}{$cur_row_ids{4}}{$cur_row_ids{5}}{cds}}, (
+              $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}} = { cdid => $cur_row_data->[3] }
+            )
+          ),
 
           # prefetch data of tracks (if available)
-          ( ! defined $cur_row_data->[0] ) ? $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}}{tracks} = [] : do {
-
-            (! $collapse_idx[5]{$cur_row_ids{0}}{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}} )
-              and
-            push @{$collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}}{tracks}}, (
-              $collapse_idx[5]{$cur_row_ids{0}}{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}} = { title => $cur_row_data->[0] }
-            );
-          };
-        };
-      };
+          (( ! defined $cur_row_data->[0] ) ? $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}}{tracks} = [] : do {
+
+            (
+              (! $collapse_idx[5]{$cur_row_ids{0}}{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}} )
+                and
+              push @{$collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}}{tracks}}, (
+                $collapse_idx[5]{$cur_row_ids{0}}{$cur_row_ids{1}}{$cur_row_ids{3}}{$cur_row_ids{4}}{$cur_row_ids{5}} = { title => $cur_row_data->[0] }
+              )
+            ),
+          } ),
+        } ),
+      } ),
     }
     $#{$_[0]} = $result_pos - 1;
   ',
@@ -462,53 +470,61 @@ is_same_src (
       ( $_[1] and $_[1]->() )
     ) ) {
 
-      @cur_row_ids{0, 1, 5, 6, 8, 10} = (
+      ( @cur_row_ids{0, 1, 5, 6, 8, 10} = (
         $cur_row_data->[0] // "\0NULL\xFF$rows_pos\xFF0\0",
         $cur_row_data->[1] // "\0NULL\xFF$rows_pos\xFF1\0",
         $cur_row_data->[5] // "\0NULL\xFF$rows_pos\xFF5\0",
         $cur_row_data->[6] // "\0NULL\xFF$rows_pos\xFF6\0",
         $cur_row_data->[8] // "\0NULL\xFF$rows_pos\xFF8\0",
         $cur_row_data->[10] // "\0NULL\xFF$rows_pos\xFF10\0",
-      );
+      ) ),
 
       # a present cref in $_[1] implies lazy prefetch, implies a supplied stash in $_[2]
-      $_[1] and $result_pos and ! $collapse_idx[0]{$cur_row_ids{1}} and (unshift @{$_[2]}, $cur_row_data) and last;
-
-      $collapse_idx[0]{$cur_row_ids{1}} //= $_[0][$result_pos++] = [{ genreid => $cur_row_data->[4], latest_cd => $cur_row_data->[7], year => $cur_row_data->[3] }];
-
-      $collapse_idx[0]{$cur_row_ids{1}}[1]{existing_single_track} //= $collapse_idx[1]{$cur_row_ids{1}} = [];
-      $collapse_idx[1]{$cur_row_ids{1}}[1]{cd} //= $collapse_idx[2]{$cur_row_ids{1}} = [];
-      $collapse_idx[2]{$cur_row_ids{1}}[1]{artist} //= $collapse_idx[3]{$cur_row_ids{1}} = [{ artistid => $cur_row_data->[1] }];
-
-      (! $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{6}} )
-        and
-      push @{ $collapse_idx[3]{$cur_row_ids{1}}[1]{cds} }, (
-        $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{6}} = [{ cdid => $cur_row_data->[6], genreid => $cur_row_data->[9], year => $cur_row_data->[2] }]
-      );
-      defined($cur_row_data->[6]) or bless( $collapse_idx[3]{$cur_row_ids{1}}[1]{cds}, __NBC__ );
-
-      (! $collapse_idx[5]{$cur_row_ids{1}}{$cur_row_ids{6}}{$cur_row_ids{8}} )
-        and
-      push @{ $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{6}}[1]{tracks} }, (
-        $collapse_idx[5]{$cur_row_ids{1}}{$cur_row_ids{6}}{$cur_row_ids{8}} = [{ title => $cur_row_data->[8] }]
-      );
-      defined($cur_row_data->[8]) or bless( $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{6}}[1]{tracks}, __NBC__ );
-
-      (! $collapse_idx[6]{$cur_row_ids{1}}{$cur_row_ids{5}} )
-        and
-      push @{ $collapse_idx[0]{$cur_row_ids{1}}[1]{tracks} }, (
-        $collapse_idx[6]{$cur_row_ids{1}}{$cur_row_ids{5}} = [{ title => $cur_row_data->[5] }]
-      );
-      defined($cur_row_data->[5]) or bless( $collapse_idx[0]{$cur_row_ids{1}}[1]{tracks}, __NBC__ );
-
-      $collapse_idx[6]{$cur_row_ids{1}}{$cur_row_ids{5}}[1]{lyrics} //= $collapse_idx[7]{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}} = [];
-      defined($cur_row_data->[10]) or bless( $collapse_idx[6]{$cur_row_ids{1}}{$cur_row_ids{5}}[1]{lyrics}, __NBC__ );
-
-      (! $collapse_idx[8]{$cur_row_ids{0}}{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}} )
-        and
-      push @{ $collapse_idx[7]{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}}[1]{existing_lyric_versions} }, (
-        $collapse_idx[8]{$cur_row_ids{0}}{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}} = [{ lyric_id => $cur_row_data->[10], text => $cur_row_data->[0] }]
-      );
+      ( $_[1] and $result_pos and ! $collapse_idx[0]{$cur_row_ids{1}} and (unshift @{$_[2]}, $cur_row_data) and last ),
+
+      ( $collapse_idx[0]{$cur_row_ids{1}} //= $_[0][$result_pos++] = [{ genreid => $cur_row_data->[4], latest_cd => $cur_row_data->[7], year => $cur_row_data->[3] }] ),
+
+      ( $collapse_idx[0]{$cur_row_ids{1}}[1]{existing_single_track} //= $collapse_idx[1]{$cur_row_ids{1}} = [] ),
+      ( $collapse_idx[1]{$cur_row_ids{1}}[1]{cd} //= $collapse_idx[2]{$cur_row_ids{1}} = [] ),
+      ( $collapse_idx[2]{$cur_row_ids{1}}[1]{artist} //= $collapse_idx[3]{$cur_row_ids{1}} = [{ artistid => $cur_row_data->[1] }] ),
+
+      (
+        (! $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{6}} )
+          and
+        push @{ $collapse_idx[3]{$cur_row_ids{1}}[1]{cds} }, (
+          $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{6}} = [{ cdid => $cur_row_data->[6], genreid => $cur_row_data->[9], year => $cur_row_data->[2] }]
+        )
+      ),
+      ( defined($cur_row_data->[6]) or bless( $collapse_idx[3]{$cur_row_ids{1}}[1]{cds}, __NBC__ ) ),
+
+      (
+        (! $collapse_idx[5]{$cur_row_ids{1}}{$cur_row_ids{6}}{$cur_row_ids{8}} )
+          and
+        push @{ $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{6}}[1]{tracks} }, (
+          $collapse_idx[5]{$cur_row_ids{1}}{$cur_row_ids{6}}{$cur_row_ids{8}} = [{ title => $cur_row_data->[8] }]
+        )
+      ),
+      ( defined($cur_row_data->[8]) or bless( $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{6}}[1]{tracks}, __NBC__ ) ),
+
+      (
+        (! $collapse_idx[6]{$cur_row_ids{1}}{$cur_row_ids{5}} )
+          and
+        push @{ $collapse_idx[0]{$cur_row_ids{1}}[1]{tracks} }, (
+          $collapse_idx[6]{$cur_row_ids{1}}{$cur_row_ids{5}} = [{ title => $cur_row_data->[5] }]
+        )
+      ),
+      ( defined($cur_row_data->[5]) or bless( $collapse_idx[0]{$cur_row_ids{1}}[1]{tracks}, __NBC__ ) ),
+
+      ( $collapse_idx[6]{$cur_row_ids{1}}{$cur_row_ids{5}}[1]{lyrics} //= $collapse_idx[7]{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}} = [] ),
+      ( defined($cur_row_data->[10]) or bless( $collapse_idx[6]{$cur_row_ids{1}}{$cur_row_ids{5}}[1]{lyrics}, __NBC__ ) ),
+
+      (
+        (! $collapse_idx[8]{$cur_row_ids{0}}{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}} )
+          and
+        push @{ $collapse_idx[7]{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}}[1]{existing_lyric_versions} }, (
+          $collapse_idx[8]{$cur_row_ids{0}}{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}} = [{ lyric_id => $cur_row_data->[10], text => $cur_row_data->[0] }]
+        )
+      ),
     }
 
     $#{$_[0]} = $result_pos - 1;
@@ -539,53 +555,60 @@ is_same_src (
       ( $_[1] and $_[1]->() )
     ) ) {
 
-      @cur_row_ids{( 0, 1, 5, 6, 8, 10 )} = @{$cur_row_data}[( 0, 1, 5, 6, 8, 10 )];
+      ( @cur_row_ids{( 0, 1, 5, 6, 8, 10 )} = @{$cur_row_data}[( 0, 1, 5, 6, 8, 10 )] ),
 
       # a present cref in $_[1] implies lazy prefetch, implies a supplied stash in $_[2]
-      $_[1] and $result_pos and ! $collapse_idx[0]{$cur_row_ids{1}} and (unshift @{$_[2]}, $cur_row_data) and last;
+      ( $_[1] and $result_pos and ! $collapse_idx[0]{$cur_row_ids{1}} and (unshift @{$_[2]}, $cur_row_data) and last ),
 
-      $collapse_idx[0]{$cur_row_ids{1}} //= $_[0][$result_pos++] = [{ genreid => $cur_row_data->[4], latest_cd => $cur_row_data->[7], year => $cur_row_data->[3] }];
+      ( $collapse_idx[0]{$cur_row_ids{1}} //= $_[0][$result_pos++] = [{ genreid => $cur_row_data->[4], latest_cd => $cur_row_data->[7], year => $cur_row_data->[3] }] ),
 
-      $collapse_idx[0]{$cur_row_ids{1}}[1]{existing_single_track} //= $collapse_idx[1]{$cur_row_ids{1}} = [];
-      $collapse_idx[1]{$cur_row_ids{1}}[1]{cd} //= $collapse_idx[2]{$cur_row_ids{1}} = [];
-      $collapse_idx[2]{$cur_row_ids{1}}[1]{artist} //= $collapse_idx[3]{$cur_row_ids{1}} = [{ artistid => $cur_row_data->[1] }];
+      ( $collapse_idx[0]{$cur_row_ids{1}}[1]{existing_single_track} //= $collapse_idx[1]{$cur_row_ids{1}} = [] ),
+      ( $collapse_idx[1]{$cur_row_ids{1}}[1]{cd} //= $collapse_idx[2]{$cur_row_ids{1}} = [] ),
+      ( $collapse_idx[2]{$cur_row_ids{1}}[1]{artist} //= $collapse_idx[3]{$cur_row_ids{1}} = [{ artistid => $cur_row_data->[1] }] ),
 
-      (! defined($cur_row_data->[6])) ? $collapse_idx[3]{$cur_row_ids{1}}[1]{cds} = [] : do {
-        (! $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{6}} )
-          and
-        push @{ $collapse_idx[3]{$cur_row_ids{1}}[1]{cds} }, (
-          $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{6}} = [{ cdid => $cur_row_data->[6], genreid => $cur_row_data->[9], year => $cur_row_data->[2] }]
-        );
-
-        (! defined($cur_row_data->[8]) ) ? $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{6}}[1]{tracks} = [] : do {
-
-          (! $collapse_idx[5]{$cur_row_ids{1}}{$cur_row_ids{6}}{$cur_row_ids{8}} )
+      ( (! defined($cur_row_data->[6])) ? $collapse_idx[3]{$cur_row_ids{1}}[1]{cds} = [] : do {
+        (
+          (! $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{6}} )
             and
-          push @{ $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{6}}[1]{tracks} }, (
-            $collapse_idx[5]{$cur_row_ids{1}}{$cur_row_ids{6}}{$cur_row_ids{8}} = [{ title => $cur_row_data->[8] }]
-          );
-        };
-      };
+          push @{ $collapse_idx[3]{$cur_row_ids{1}}[1]{cds} }, (
+            $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{6}} = [{ cdid => $cur_row_data->[6], genreid => $cur_row_data->[9], year => $cur_row_data->[2] }]
+          )
+        ),
+
+        ( (! defined($cur_row_data->[8]) ) ? $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{6}}[1]{tracks} = [] : do {
+          (
+            (! $collapse_idx[5]{$cur_row_ids{1}}{$cur_row_ids{6}}{$cur_row_ids{8}} )
+              and
+            push @{ $collapse_idx[4]{$cur_row_ids{1}}{$cur_row_ids{6}}[1]{tracks} }, (
+              $collapse_idx[5]{$cur_row_ids{1}}{$cur_row_ids{6}}{$cur_row_ids{8}} = [{ title => $cur_row_data->[8] }]
+            )
+          ),
+        } ),
+      } ),
 
-      (! defined($cur_row_data->[5]) ) ? $collapse_idx[0]{$cur_row_ids{1}}[1]{tracks} = [] : do {
+      ( (! defined($cur_row_data->[5]) ) ? $collapse_idx[0]{$cur_row_ids{1}}[1]{tracks} = [] : do {
 
-        (! $collapse_idx[6]{$cur_row_ids{1}}{$cur_row_ids{5}} )
-          and
-        push @{ $collapse_idx[0]{$cur_row_ids{1}}[1]{tracks} }, (
-          $collapse_idx[6]{$cur_row_ids{1}}{$cur_row_ids{5}} = [{ title => $cur_row_data->[5] }]
-        );
+        (
+          (! $collapse_idx[6]{$cur_row_ids{1}}{$cur_row_ids{5}} )
+            and
+          push @{ $collapse_idx[0]{$cur_row_ids{1}}[1]{tracks} }, (
+            $collapse_idx[6]{$cur_row_ids{1}}{$cur_row_ids{5}} = [{ title => $cur_row_data->[5] }]
+          )
+        ),
 
-        (! defined($cur_row_data->[10]) ) ? $collapse_idx[6]{$cur_row_ids{1}}{$cur_row_ids{5}}[1]{lyrics} = [] : do {
+        ( (! defined($cur_row_data->[10]) ) ? $collapse_idx[6]{$cur_row_ids{1}}{$cur_row_ids{5}}[1]{lyrics} = [] : do {
 
-          $collapse_idx[6]{$cur_row_ids{1}}{$cur_row_ids{5}}[1]{lyrics} //= $collapse_idx[7]{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}} = [];
+          ( $collapse_idx[6]{$cur_row_ids{1}}{$cur_row_ids{5}}[1]{lyrics} //= $collapse_idx[7]{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}} = [] ),
 
-          (! $collapse_idx[8]{$cur_row_ids{0}}{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}} )
-            and
-          push @{ $collapse_idx[7]{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}}[1]{existing_lyric_versions} }, (
-            $collapse_idx[8]{$cur_row_ids{0}}{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}} = [{ lyric_id => $cur_row_data->[10], text => $cur_row_data->[0] }]
-          );
-        };
-      };
+          (
+            (! $collapse_idx[8]{$cur_row_ids{0}}{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}} )
+              and
+            push @{ $collapse_idx[7]{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}}[1]{existing_lyric_versions} }, (
+              $collapse_idx[8]{$cur_row_ids{0}}{$cur_row_ids{1}}{$cur_row_ids{5}}{$cur_row_ids{10}} = [{ lyric_id => $cur_row_data->[10], text => $cur_row_data->[0] }]
+            )
+          ),
+        } ),
+      } ),
     }
 
     $#{$_[0]} = $result_pos - 1;
@@ -663,55 +686,61 @@ is_same_src (
       ( $_[1] and $_[1]->() )
     ) ) {
 
-      @cur_row_ids{( 0, 2, 3, 4, 8 )} = (
+      ( @cur_row_ids{( 0, 2, 3, 4, 8 )} = (
         $cur_row_data->[0] // "\0NULL\xFF$rows_pos\xFF0\0",
         $cur_row_data->[2] // "\0NULL\xFF$rows_pos\xFF2\0",
         $cur_row_data->[3] // "\0NULL\xFF$rows_pos\xFF3\0",
         $cur_row_data->[4] // "\0NULL\xFF$rows_pos\xFF4\0",
         $cur_row_data->[8] // "\0NULL\xFF$rows_pos\xFF8\0",
-      );
+      )),
 
       # cache expensive set of ops in a non-existent rowid slot
-      $cur_row_ids{10} = (
+      ( $cur_row_ids{10} = (
         ( ( defined $cur_row_data->[0] ) && (join "\xFF", q{}, $cur_row_ids{0}, q{} ))
           or
         ( ( defined $cur_row_data->[2] ) && (join "\xFF", q{}, $cur_row_ids{2}, q{} ))
           or
         "\0$rows_pos\0"
-      );
+      )),
 
       # a present cref in $_[1] implies lazy prefetch, implies a supplied stash in $_[2]
-      $_[1] and $result_pos and ! $collapse_idx[0]{$cur_row_ids{10}} and (unshift @{$_[2]}, $cur_row_data) and last;
+      ( $_[1] and $result_pos and ! $collapse_idx[0]{$cur_row_ids{10}} and (unshift @{$_[2]}, $cur_row_data) and last ),
 
-      $collapse_idx[0]{$cur_row_ids{10}} //= $_[0][$result_pos++] = [{ year => $$cur_row_data[1] }];
+      ( $collapse_idx[0]{$cur_row_ids{10}} //= $_[0][$result_pos++] = [{ year => $$cur_row_data[1] }] ),
 
-      $collapse_idx[0]{$cur_row_ids{10}}[1]{single_track} //= ($collapse_idx[1]{$cur_row_ids{0}} = [{ trackid => $cur_row_data->[0] }]);
-      defined($cur_row_data->[0]) or bless ( $collapse_idx[0]{$cur_row_ids{10}}[1]{single_track}, __NBC__ );
+      ( $collapse_idx[0]{$cur_row_ids{10}}[1]{single_track} //= ($collapse_idx[1]{$cur_row_ids{0}} = [{ trackid => $cur_row_data->[0] }]) ),
+      ( defined($cur_row_data->[0]) or bless ( $collapse_idx[0]{$cur_row_ids{10}}[1]{single_track}, __NBC__ ) ),
 
-      $collapse_idx[1]{$cur_row_ids{0}}[1]{cd} //= $collapse_idx[2]{$cur_row_ids{0}} = [];
+      ( $collapse_idx[1]{$cur_row_ids{0}}[1]{cd} //= $collapse_idx[2]{$cur_row_ids{0}} = [] ),
 
-      $collapse_idx[2]{$cur_row_ids{0}}[1]{artist} //= ($collapse_idx[3]{$cur_row_ids{0}} = [{ artistid => $cur_row_data->[6] }]);
+      ( $collapse_idx[2]{$cur_row_ids{0}}[1]{artist} //= ($collapse_idx[3]{$cur_row_ids{0}} = [{ artistid => $cur_row_data->[6] }]) ),
 
-      (! $collapse_idx[4]{$cur_row_ids{0}}{$cur_row_ids{4}} )
-        and
-      push @{$collapse_idx[3]{$cur_row_ids{0}}[1]{cds}}, (
+      (
+        (! $collapse_idx[4]{$cur_row_ids{0}}{$cur_row_ids{4}} )
+          and
+        push @{$collapse_idx[3]{$cur_row_ids{0}}[1]{cds}}, (
           $collapse_idx[4]{$cur_row_ids{0}}{$cur_row_ids{4}} = [{ cdid => $cur_row_data->[4], genreid => $cur_row_data->[7], year => $cur_row_data->[5] }]
-      );
-      defined($cur_row_data->[4]) or bless ( $collapse_idx[3]{$cur_row_ids{0}}[1]{cds}, __NBC__ );
-
-      (! $collapse_idx[5]{$cur_row_ids{0}}{$cur_row_ids{4}}{$cur_row_ids{8}} )
-        and
-      push @{$collapse_idx[4]{$cur_row_ids{0}}{$cur_row_ids{4}}[1]{tracks}}, (
-          $collapse_idx[5]{$cur_row_ids{0}}{$cur_row_ids{4}}{$cur_row_ids{8}} = [{ title => $cur_row_data->[8] }]
-      );
-      defined($cur_row_data->[8]) or bless ( $collapse_idx[4]{$cur_row_ids{0}}{$cur_row_ids{4}}[1]{tracks}, __NBC__ );
-
-      (! $collapse_idx[6]{$cur_row_ids{2}}{$cur_row_ids{3}} )
-        and
-      push @{$collapse_idx[0]{$cur_row_ids{10}}[1]{tracks}}, (
+        )
+      ),
+      ( defined($cur_row_data->[4]) or bless ( $collapse_idx[3]{$cur_row_ids{0}}[1]{cds}, __NBC__ ) ),
+
+      (
+        (! $collapse_idx[5]{$cur_row_ids{0}}{$cur_row_ids{4}}{$cur_row_ids{8}} )
+          and
+        push @{$collapse_idx[4]{$cur_row_ids{0}}{$cur_row_ids{4}}[1]{tracks}}, (
+            $collapse_idx[5]{$cur_row_ids{0}}{$cur_row_ids{4}}{$cur_row_ids{8}} = [{ title => $cur_row_data->[8] }]
+        )
+      ),
+      ( defined($cur_row_data->[8]) or bless ( $collapse_idx[4]{$cur_row_ids{0}}{$cur_row_ids{4}}[1]{tracks}, __NBC__ ) ),
+
+      (
+        (! $collapse_idx[6]{$cur_row_ids{2}}{$cur_row_ids{3}} )
+          and
+        push @{$collapse_idx[0]{$cur_row_ids{10}}[1]{tracks}}, (
           $collapse_idx[6]{$cur_row_ids{2}}{$cur_row_ids{3}} = [{ cd => $$cur_row_data[2], title => $cur_row_data->[3] }]
-      );
-      defined($cur_row_data->[2]) or bless ( $collapse_idx[0]{$cur_row_ids{10}}[1]{tracks}, __NBC__ );
+        )
+      ),
+      ( defined($cur_row_data->[2]) or bless ( $collapse_idx[0]{$cur_row_ids{10}}[1]{tracks}, __NBC__ ) ),
     }
 
     $#{$_[0]} = $result_pos - 1;
@@ -744,56 +773,60 @@ is_same_src (
     ) ) {
 
       # do not care about nullability here
-      @cur_row_ids{( 0, 2, 3, 4, 8 )} = @{$cur_row_data}[( 0, 2, 3, 4, 8 )];
+      ( @cur_row_ids{( 0, 2, 3, 4, 8 )} = @{$cur_row_data}[( 0, 2, 3, 4, 8 )] ),
 
       # cache expensive set of ops in a non-existent rowid slot
-      $cur_row_ids{10} = (
+      ( $cur_row_ids{10} = (
         ( ( defined $cur_row_data->[0] ) && (join "\xFF", q{}, $cur_row_ids{0}, q{} ))
           or
         ( ( defined $cur_row_data->[2] ) && (join "\xFF", q{}, $cur_row_ids{2}, q{} ))
           or
         "\0$rows_pos\0"
-      );
+      )),
 
       # a present cref in $_[1] implies lazy prefetch, implies a supplied stash in $_[2]
-      $_[1] and $result_pos and ! $collapse_idx[0]{$cur_row_ids{10}} and (unshift @{$_[2]}, $cur_row_data) and last;
+      ( $_[1] and $result_pos and ! $collapse_idx[0]{$cur_row_ids{10}} and (unshift @{$_[2]}, $cur_row_data) and last ),
 
-      $collapse_idx[0]{$cur_row_ids{10}} //= $_[0][$result_pos++] = { year => $$cur_row_data[1] };
+      ( $collapse_idx[0]{$cur_row_ids{10}} //= $_[0][$result_pos++] = { year => $$cur_row_data[1] } ),
 
-      (! defined $cur_row_data->[0] ) ? $collapse_idx[0]{$cur_row_ids{10}}{single_track} = undef : do {
+      ( (! defined $cur_row_data->[0] ) ? $collapse_idx[0]{$cur_row_ids{10}}{single_track} = undef : do {
 
-        $collapse_idx[0]{$cur_row_ids{10}}{single_track} //= ($collapse_idx[1]{$cur_row_ids{0}} = { trackid => $$cur_row_data[0] });
+        ( $collapse_idx[0]{$cur_row_ids{10}}{single_track} //= ($collapse_idx[1]{$cur_row_ids{0}} = { trackid => $$cur_row_data[0] }) ),
 
-        $collapse_idx[1]{$cur_row_ids{0}}{cd} //= $collapse_idx[2]{$cur_row_ids{0}};
+        ( $collapse_idx[1]{$cur_row_ids{0}}{cd} //= $collapse_idx[2]{$cur_row_ids{0}} ),
 
-        $collapse_idx[2]{$cur_row_ids{0}}{artist} //= ($collapse_idx[3]{$cur_row_ids{0}} = { artistid => $$cur_row_data[6] });
+        ( $collapse_idx[2]{$cur_row_ids{0}}{artist} //= ($collapse_idx[3]{$cur_row_ids{0}} = { artistid => $$cur_row_data[6] }) ),
 
-        (! defined $cur_row_data->[4] ) ? $collapse_idx[3]{$cur_row_ids{0}}{cds} = [] : do {
+        ( (! defined $cur_row_data->[4] ) ? $collapse_idx[3]{$cur_row_ids{0}}{cds} = [] : do {
 
-          (! $collapse_idx[4]{$cur_row_ids{0}}{$cur_row_ids{4}} )
-            and
-          push @{$collapse_idx[3]{$cur_row_ids{0}}{cds}}, (
-              $collapse_idx[4]{$cur_row_ids{0}}{$cur_row_ids{4}} = { cdid => $$cur_row_data[4], genreid => $$cur_row_data[7], year => $$cur_row_data[5] }
-          );
+          (
+            (! $collapse_idx[4]{$cur_row_ids{0}}{$cur_row_ids{4}} )
+              and
+            push @{$collapse_idx[3]{$cur_row_ids{0}}{cds}}, (
+                $collapse_idx[4]{$cur_row_ids{0}}{$cur_row_ids{4}} = { cdid => $$cur_row_data[4], genreid => $$cur_row_data[7], year => $$cur_row_data[5] }
+            )
+          ),
 
-          (! defined $cur_row_data->[8] ) ? $collapse_idx[4]{$cur_row_ids{0}}{$cur_row_ids{4}}{tracks} = [] : do {
+          ( (! defined $cur_row_data->[8] ) ? $collapse_idx[4]{$cur_row_ids{0}}{$cur_row_ids{4}}{tracks} = [] : do {
 
             (! $collapse_idx[5]{$cur_row_ids{0}}{$cur_row_ids{4}}{$cur_row_ids{8}} )
               and
             push @{$collapse_idx[4]{$cur_row_ids{0}}{$cur_row_ids{4}}{tracks}}, (
                 $collapse_idx[5]{$cur_row_ids{0}}{$cur_row_ids{4}}{$cur_row_ids{8}} = { title => $$cur_row_data[8] }
-            );
-          };
-        };
-      };
+            ),
+          } ),
+        } ),
+      } ),
 
-      (! defined $cur_row_data->[2] ) ? $collapse_idx[0]{$cur_row_ids{10}}{tracks} = [] : do {
-        (! $collapse_idx[6]{$cur_row_ids{2}}{$cur_row_ids{3}} )
-          and
-        push @{$collapse_idx[0]{$cur_row_ids{10}}{tracks}}, (
+      ( (! defined $cur_row_data->[2] ) ? $collapse_idx[0]{$cur_row_ids{10}}{tracks} = [] : do {
+        (
+          (! $collapse_idx[6]{$cur_row_ids{2}}{$cur_row_ids{3}} )
+            and
+          push @{$collapse_idx[0]{$cur_row_ids{10}}{tracks}}, (
             $collapse_idx[6]{$cur_row_ids{2}}{$cur_row_ids{3}} = { cd => $$cur_row_data[2], title => $$cur_row_data[3] }
-        );
-      };
+          )
+        ),
+      } ),
     }
 
     $#{$_[0]} = $result_pos - 1;
@@ -824,24 +857,24 @@ is_same_src (
       ( $_[1] and $_[1]->() )
     ) ) {
 
-      @cur_row_ids{0,1} = @{$cur_row_data}[0,1];
+      ( @cur_row_ids{0,1} = @{$cur_row_data}[0,1] ),
 
-      $cur_row_ids{3} = (
+      ( $cur_row_ids{3} = (
         ( ( defined $cur_row_data->[1] ) && (join "\xFF", q{}, $cur_row_ids{1}, q{} ))
           or
         "\0${rows_pos}\0"
-      );
+      )),
 
-      $_[1] and $result_pos and ! $collapse_idx[0]{$cur_row_ids{3}} and (unshift @{$_[2]}, $cur_row_data) and last;
+      ( $_[1] and $result_pos and ! $collapse_idx[0]{$cur_row_ids{3}} and (unshift @{$_[2]}, $cur_row_data) and last ),
 
       # empty data for the root node
-      $collapse_idx[0]{$cur_row_ids{3}} //= $_[0][$result_pos++] = [];
+      ( $collapse_idx[0]{$cur_row_ids{3}} //= $_[0][$result_pos++] = [] ),
 
-      ( ! defined $cur_row_data->[0] ) ? $collapse_idx[0]{$cur_row_ids{3}}[1]{"books"} = [] : do {
+      ( ( ! defined $cur_row_data->[0] ) ? $collapse_idx[0]{$cur_row_ids{3}}[1]{"books"} = [] : do {
         push @{$collapse_idx[0]{$cur_row_ids{3}}[1]{books}},
           $collapse_idx[1]{$cur_row_ids{0}} = [ { owner => $cur_row_data->[1], title => $cur_row_data->[0] } ]
         unless $collapse_idx[1]{$cur_row_ids{0}}
-      };
+      } ),
     }
 
     $#{$_[0]} = $result_pos - 1; # truncate the passed in array to where we filled it with results