X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FStorage%2FDBIHacks.pm;h=26f8dcac1f559a252ba5ba3d69627cf32c8d9c46;hb=8d73fcd44e0441f0252744be32bada6816c5ff6b;hp=cb75f142ecd3d28e7f549519fc45d5a8c4606062;hpb=946f626022c63fd269d9d985c2abeabb52871027;p=dbsrgits%2FDBIx-Class.git diff --git a/lib/DBIx/Class/Storage/DBIHacks.pm b/lib/DBIx/Class/Storage/DBIHacks.pm index cb75f14..26f8dca 100644 --- a/lib/DBIx/Class/Storage/DBIHacks.pm +++ b/lib/DBIx/Class/Storage/DBIHacks.pm @@ -15,7 +15,8 @@ use mro 'c3'; use List::Util 'first'; use Scalar::Util 'blessed'; -use Sub::Name 'subname'; +use DBIx::Class::_Util 'UNRESOLVABLE_CONDITION'; +use SQL::Abstract qw(is_plain_value is_literal_value); use namespace::clean; # @@ -23,40 +24,68 @@ use namespace::clean; # {from} specs, aiding the RDBMS query optimizer # sub _prune_unused_joins { - my $self = shift; - my ($from, $select, $where, $attrs) = @_; + my ($self, $attrs) = @_; + + # only standard {from} specs are supported, and we could be disabled in general + return ($attrs->{from}, {}) unless ( + ref $attrs->{from} eq 'ARRAY' + and + @{$attrs->{from}} > 1 + and + ref $attrs->{from}[0] eq 'HASH' + and + ref $attrs->{from}[1] eq 'ARRAY' + and + $self->_use_join_optimizer + ); - return $from unless $self->_use_join_optimizer; + my $orig_aliastypes = $self->_resolve_aliastypes_from_select_args($attrs); - if (ref $from ne 'ARRAY' || ref $from->[0] ne 'HASH' || ref $from->[1] ne 'ARRAY') { - return $from; # only standard {from} specs are supported - } + my $new_aliastypes = { %$orig_aliastypes }; - my $aliastypes = $self->_resolve_aliastypes_from_select_args(@_); + # we will be recreating this entirely + my @reclassify = 'joining'; # a grouped set will not be affected by amount of rows. Thus any - # {multiplying} joins can go - delete $aliastypes->{multiplying} if $attrs->{group_by}; + # purely multiplicator classifications can go + # (will be reintroduced below if needed by something else) + push @reclassify, qw(multiplying premultiplied) + if $attrs->{_force_prune_multiplying_joins} or $attrs->{group_by}; + + # nuke what will be recalculated + delete @{$new_aliastypes}{@reclassify}; - my @newfrom = $from->[0]; # FROM head is always present + my @newfrom = $attrs->{from}[0]; # FROM head is always present + # recalculate what we need once the multipliers are potentially gone + # ignore premultiplies, since they do not add any value to anything my %need_joins; - for (values %$aliastypes) { + for ( @{$new_aliastypes}{grep { $_ ne 'premultiplied' } keys %$new_aliastypes }) { # add all requested aliases $need_joins{$_} = 1 for keys %$_; # add all their parents (as per joinpath which is an AoH { table => alias }) - $need_joins{$_} = 1 for map { values %$_ } map { @$_ } values %$_; + $need_joins{$_} = 1 for map { values %$_ } map { @{$_->{-parents}} } values %$_; } - for my $j (@{$from}[1..$#$from]) { + + for my $j (@{$attrs->{from}}[1..$#{$attrs->{from}}]) { push @newfrom, $j if ( - (! $j->[0]{-alias}) # legacy crap + (! defined $j->[0]{-alias}) # legacy crap || $need_joins{$j->[0]{-alias}} ); } - return \@newfrom; + # we have a new set of joiners - for everything we nuked pull the classification + # off the original stack + for my $ctype (@reclassify) { + $new_aliastypes->{$ctype} = { map + { $need_joins{$_} ? ( $_ => $orig_aliastypes->{$ctype}{$_} ) : () } + keys %{$orig_aliastypes->{$ctype}} + } + } + + return ( \@newfrom, $new_aliastypes ); } # @@ -64,92 +93,159 @@ sub _prune_unused_joins { # SELECT me.*, other.* FROM ( SELECT me.* FROM ... ) JOIN other ON ... # sub _adjust_select_args_for_complex_prefetch { - my ($self, $from, $select, $where, $attrs) = @_; + my ($self, $attrs) = @_; + + $self->throw_exception ('Complex prefetches are not supported on resultsets with a custom from attribute') unless ( + ref $attrs->{from} eq 'ARRAY' + and + @{$attrs->{from}} > 1 + and + ref $attrs->{from}[0] eq 'HASH' + and + ref $attrs->{from}[1] eq 'ARRAY' + ); - $self->throw_exception ('Nothing to prefetch... how did we get here?!') - if not @{$attrs->{_prefetch_selector_range}}; - - $self->throw_exception ('Complex prefetches are not supported on resultsets with a custom from attribute') - if (ref $from ne 'ARRAY' || ref $from->[0] ne 'HASH' || ref $from->[1] ne 'ARRAY'); + my $root_alias = $attrs->{alias}; # generate inner/outer attribute lists, remove stuff that doesn't apply my $outer_attrs = { %$attrs }; - delete $outer_attrs->{$_} for qw/where bind rows offset group_by having/; + delete @{$outer_attrs}{qw(from bind rows offset group_by _grouped_by_distinct having)}; - my $inner_attrs = { %$attrs, _is_internal_subuery => 1 }; - delete $inner_attrs->{$_} for qw/for collapse _prefetch_selector_range select as/; + my $inner_attrs = { %$attrs }; + delete @{$inner_attrs}{qw(for collapse select as _related_results_construction)}; - # if the user did not request it, there is no point using it inside - delete $inner_attrs->{order_by} if delete $inner_attrs->{_order_is_artificial}; + # there is no point of ordering the insides if there is no limit + delete $inner_attrs->{order_by} if ( + delete $inner_attrs->{_order_is_artificial} + or + ! $inner_attrs->{rows} + ); # generate the inner/outer select lists # for inside we consider only stuff *not* brought in by the prefetch # on the outside we substitute any function for its alias - my $outer_select = [ @$select ]; - my $inner_select = []; + $outer_attrs->{select} = [ @{$attrs->{select}} ]; + + my ($root_node, $root_node_offset); + + for my $i (0 .. $#{$inner_attrs->{from}}) { + my $node = $inner_attrs->{from}[$i]; + my $h = (ref $node eq 'HASH') ? $node + : (ref $node eq 'ARRAY' and ref $node->[0] eq 'HASH') ? $node->[0] + : next + ; - my ($p_start, $p_end) = @{$outer_attrs->{_prefetch_selector_range}}; - for my $i (0 .. $p_start - 1, $p_end + 1 .. $#$outer_select) { - my $sel = $outer_select->[$i]; + if ( ($h->{-alias}||'') eq $root_alias and $h->{-rsrc} ) { + $root_node = $h; + $root_node_offset = $i; + last; + } + } + + $self->throw_exception ('Complex prefetches are not supported on resultsets with a custom from attribute') + unless $root_node; + + # use the heavy duty resolver to take care of aliased/nonaliased naming + my $colinfo = $self->_resolve_column_info($inner_attrs->{from}); + my $selected_root_columns; + + for my $i (0 .. $#{$outer_attrs->{select}}) { + my $sel = $outer_attrs->{select}->[$i]; + + next if ( + $colinfo->{$sel} and $colinfo->{$sel}{-source_alias} ne $root_alias + ); if (ref $sel eq 'HASH' ) { $sel->{-as} ||= $attrs->{as}[$i]; - $outer_select->[$i] = join ('.', $attrs->{alias}, ($sel->{-as} || "inner_column_$i") ); + $outer_attrs->{select}->[$i] = join ('.', $root_alias, ($sel->{-as} || "inner_column_$i") ); + } + elsif (! ref $sel and my $ci = $colinfo->{$sel}) { + $selected_root_columns->{$ci->{-colname}} = 1; } - push @$inner_select, $sel; + push @{$inner_attrs->{select}}, $sel; push @{$inner_attrs->{as}}, $attrs->{as}[$i]; } - # 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 - # 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) + # We will need to fetch all native columns in the inner subquery, which may + # be a part of an *outer* join condition, or an order_by (which needs to be + # preserved outside), or wheres. In other words everything but the inner + # selector + # We can not just fetch everything because a potential has_many restricting + # join collapse *will not work* on heavy data types. + my $connecting_aliastypes = $self->_resolve_aliastypes_from_select_args({ + %$inner_attrs, + select => [], + }); + + for (sort map { keys %{$_->{-seen_columns}||{}} } map { values %$_ } values %$connecting_aliastypes) { + my $ci = $colinfo->{$_} or next; + if ( + $ci->{-source_alias} eq $root_alias + and + ! $selected_root_columns->{$ci->{-colname}}++ + ) { + # adding it to both to keep limits not supporting dark selectors happy + push @{$inner_attrs->{select}}, $ci->{-fq_colname}; + push @{$inner_attrs->{as}}, $ci->{-fq_colname}; + } + } + # 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 + # throw away all non-selecting, non-restricting multijoins + # (since we def. do not care about multiplication of the contents of the subquery) my $inner_subq = do { - # must use it here regardless of user requests + # must use it here regardless of user requests (vastly gentler on optimizer) local $self->{_use_join_optimizer} = 1; - my $inner_from = $self->_prune_unused_joins ($from, $inner_select, $where, { - group_by => ['dummy'], %$inner_attrs, + # throw away multijoins since we def. do not care about those inside the subquery + ($inner_attrs->{from}, my $inner_aliastypes) = $self->_prune_unused_joins ({ + %$inner_attrs, _force_prune_multiplying_joins => 1 }); - my $inner_aliastypes = - $self->_resolve_aliastypes_from_select_args( $inner_from, $inner_select, $where, $inner_attrs ); - - # we need to simulate collapse in the subq if a multiplying join is pulled - # by being a non-selecting restrictor + # uh-oh a multiplier (which is not us) left in, this is a problem for limits + # we will need to add a group_by to collapse the resultset for proper counts if ( - ! $inner_attrs->{group_by} + grep { $_ ne $root_alias } keys %{ $inner_aliastypes->{multiplying} || {} } and - first { - $inner_aliastypes->{restricting}{$_} - and - ! $inner_aliastypes->{selecting}{$_} - } ( keys %{$inner_aliastypes->{multiplying}||{}} ) + # if there are user-supplied groups - assume user knows wtf they are up to + ( ! $inner_aliastypes->{grouping} or $inner_attrs->{_grouped_by_distinct} ) ) { - my $unprocessed_order_chunks; - ($inner_attrs->{group_by}, $unprocessed_order_chunks) = $self->_group_over_selection ( - $inner_from, $inner_select, $inner_attrs->{order_by} - ); - $self->throw_exception ( - 'A required group_by clause could not be constructed automatically due to a complex ' - . 'order_by criteria. Either order_by columns only (no functions) or construct a suitable ' - . 'group_by by hand' - ) if $unprocessed_order_chunks; + my $cur_sel = { map { $_ => 1 } @{$inner_attrs->{select}} }; + + # *possibly* supplement the main selection with pks if not already + # there, as they will have to be a part of the group_by to collapse + # things properly + my $inner_select_with_extras; + my @pks = map { "$root_alias.$_" } $root_node->{-rsrc}->primary_columns + or $self->throw_exception( sprintf + 'Unable to perform complex limited prefetch off %s without declared primary key', + $root_node->{-rsrc}->source_name, + ); + for my $col (@pks) { + push @{ $inner_select_with_extras ||= [ @{$inner_attrs->{select}} ] }, $col + unless $cur_sel->{$col}++; + } + + ($inner_attrs->{group_by}, $inner_attrs->{order_by}) = $self->_group_over_selection({ + %$inner_attrs, + $inner_select_with_extras ? ( select => $inner_select_with_extras ) : (), + _aliastypes => $inner_aliastypes, + }); } - # we already optimized $inner_from above - local $self->{_use_join_optimizer} = 0; + # we already optimized $inner_attrs->{from} above + # and already local()ized + $self->{_use_join_optimizer} = 0; # generate the subquery $self->_select_args_to_query ( - $inner_from, - $inner_select, - $where, + @{$inner_attrs}{qw(from select where)}, $inner_attrs, ); }; @@ -164,45 +260,51 @@ 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 - $from = [ @$from ]; + # work on a shallow copy + my @orig_from = @{$attrs->{from}}; - # 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 + $outer_attrs->{from} = \ my @outer_from; - push @outer_from, [ - { - -alias => $attrs->{alias}, - -rsrc => $j->[0]{-rsrc}, - $attrs->{alias} => $inner_subq, - }, - @{$j}[1 .. $#$j], - ]; - last; # we'll take care of what's left in $from below - } - else { - push @outer_from, $j; - } + # we may not be the head + if ($root_node_offset) { + # first generate the outer_from, up to the substitution point + @outer_from = splice @orig_from, 0, $root_node_offset; + + # substitute the subq at the right spot + push @outer_from, [ + { + -alias => $root_alias, + -rsrc => $root_node->{-rsrc}, + $root_alias => $inner_subq, + }, + # preserve attrs from what is now the head of the from after the splice + @{$orig_from[0]}[1 .. $#{$orig_from[0]}], + ]; } + else { + @outer_from = { + -alias => $root_alias, + -rsrc => $root_node->{-rsrc}, + $root_alias => $inner_subq, + }; + } + + shift @orig_from; # what we just replaced above # 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 ); + my $outer_aliastypes = $outer_attrs->{_aliastypes} = + $self->_resolve_aliastypes_from_select_args({ %$outer_attrs, from => \@orig_from }); # unroll parents - my ($outer_select_chain, $outer_restrict_chain) = map { +{ - map { $_ => 1 } map { values %$_} map { @$_ } values %{ $outer_aliastypes->{$_} || {} } - } } qw/selecting restricting/; + my ($outer_select_chain, @outer_nonselecting_chains) = map { +{ + map { $_ => 1 } map { values %$_} map { @{$_->{-parents}} } values %{ $outer_aliastypes->{$_} || {} } + } } qw/selecting restricting grouping ordering/; # see what's left - throw away if not selecting/restricting - # also throw in a group_by if a non-selecting multiplier, - # to guard against cross-join explosions - my $need_outer_group_by; - while (my $j = shift @$from) { + my $may_need_outer_group_by; + while (my $j = shift @orig_from) { my $alias = $j->[0]{-alias}; if ( @@ -210,38 +312,31 @@ sub _adjust_select_args_for_complex_prefetch { ) { push @outer_from, $j } - elsif ($outer_restrict_chain->{$alias}) { + elsif (first { $_->{$alias} } @outer_nonselecting_chains ) { push @outer_from, $j; - $need_outer_group_by ||= $outer_aliastypes->{multiplying}{$alias} ? 1 : 0; + $may_need_outer_group_by ||= $outer_aliastypes->{multiplying}{$alias} ? 1 : 0; } } - # demote the outer_from head - $outer_from[0] = $outer_from[0][0]; - - if ($need_outer_group_by and ! $outer_attrs->{group_by}) { - - my $unprocessed_order_chunks; - ($outer_attrs->{group_by}, $unprocessed_order_chunks) = $self->_group_over_selection ( - \@outer_from, $outer_select, $outer_attrs->{order_by} - ); - - $self->throw_exception ( - 'A required group_by clause could not be constructed automatically due to a complex ' - . 'order_by criteria. Either order_by columns only (no functions) or construct a suitable ' - . 'group_by by hand' - ) if $unprocessed_order_chunks; - + # also throw in a synthetic group_by if a non-selecting multiplier, + # to guard against cross-join explosions + # the logic is somewhat fragile, but relies on the idea that if a user supplied + # a group by on their own - they know what they were doing + if ( $may_need_outer_group_by and $attrs->{_grouped_by_distinct} ) { + ($outer_attrs->{group_by}, $outer_attrs->{order_by}) = $self->_group_over_selection ({ + %$outer_attrs, + from => \@outer_from, + }); } - # This is totally horrific - the $where ends up in both the inner and outer query + # This is totally horrific - the {where} ends up in both the inner and outer query # Unfortunately not much can be done until SQLA2 introspection arrives, and even # then if where conditions apply to the *right* side of the prefetch, you may have # to both filter the inner select (e.g. to apply a limit) and then have to re-filter - # the outer select to exclude joins you didin't want in the first place + # the outer select to exclude joins you didn't want in the first place # # OTOH it can be seen as a plus: (notes that this query would make a DBA cry ;) - return (\@outer_from, $outer_select, $where, $outer_attrs); + return $outer_attrs; } # @@ -249,50 +344,56 @@ sub _adjust_select_args_for_complex_prefetch { # # Due to a lack of SQLA2 we fall back to crude scans of all the # select/where/order/group attributes, in order to determine what -# aliases are neded to fulfill the query. This information is used +# aliases are needed to fulfill the query. This information is used # throughout the code to prune unnecessary JOINs from the queries # in an attempt to reduce the execution time. # Although the method is pretty horrific, the worst thing that can # happen is for it to fail due to some scalar SQL, which in turn will # result in a vocal exception. sub _resolve_aliastypes_from_select_args { - my ( $self, $from, $select, $where, $attrs ) = @_; + my ( $self, $attrs ) = @_; $self->throw_exception ('Unable to analyze custom {from}') - if ref $from ne 'ARRAY'; + if ref $attrs->{from} ne 'ARRAY'; # what we will return my $aliases_by_type; # see what aliases are there to work with + # and record who is a multiplier and who is premultiplied my $alias_list; - for (@$from) { - my $j = $_; + for my $node (@{$attrs->{from}}) { + + my $j = $node; $j = $j->[0] if ref $j eq 'ARRAY'; my $al = $j->{-alias} or next; $alias_list->{$al} = $j; - $aliases_by_type->{multiplying}{$al} ||= $j->{-join_path}||[] if ( + + $aliases_by_type->{multiplying}{$al} ||= { -parents => $j->{-join_path}||[] } # not array == {from} head == can't be multiplying - ( ref($_) eq 'ARRAY' and ! $j->{-is_single} ) - or - # a parent of ours is already a multiplier - ( grep { $aliases_by_type->{multiplying}{$_} } @{ $j->{-join_path}||[] } ) - ); + if ref($node) eq 'ARRAY' and ! $j->{-is_single}; + + $aliases_by_type->{premultiplied}{$al} ||= { -parents => $j->{-join_path}||[] } + # parts of the path that are not us but are multiplying + if grep { $aliases_by_type->{multiplying}{$_} } + grep { $_ ne $al } + map { values %$_ } + @{ $j->{-join_path}||[] } } - # get a column to source/alias map (including unqualified ones) - my $colinfo = $self->_resolve_column_info ($from); + # get a column to source/alias map (including unambiguous unqualified ones) + my $colinfo = $self->_resolve_column_info ($attrs->{from}); # set up a botched SQLA my $sql_maker = $self->sql_maker; # these are throw away results, do not pollute the bind stack - local $sql_maker->{select_bind}; local $sql_maker->{where_bind}; local $sql_maker->{group_bind}; local $sql_maker->{having_bind}; + local $sql_maker->{from_bind}; # we can't scan properly without any quoting (\b doesn't cut it # everywhere), so unless there is proper quoting set - use our @@ -315,33 +416,86 @@ sub _resolve_aliastypes_from_select_args { # generate sql chunks my $to_scan = { restricting => [ - $sql_maker->_recurse_where ($where), - $sql_maker->_parse_rs_attrs ({ - map { $_ => $attrs->{$_} } (qw/group_by having/) - }), + $sql_maker->_recurse_where ($attrs->{where}), + $sql_maker->_parse_rs_attrs ({ having => $attrs->{having} }), + ], + grouping => [ + $sql_maker->_parse_rs_attrs ({ group_by => $attrs->{group_by} }), + ], + joining => [ + $sql_maker->_recurse_from ( + ref $attrs->{from}[0] eq 'ARRAY' ? $attrs->{from}[0][0] : $attrs->{from}[0], + @{$attrs->{from}}[1 .. $#{$attrs->{from}}], + ), ], selecting => [ - $sql_maker->_recurse_fields ($select), - ( map { $_->[0] } $self->_extract_order_criteria ($attrs->{order_by}, $sql_maker) ), + map { ($sql_maker->_recurse_fields($_))[0] } @{$attrs->{select}}, + ], + ordering => [ + map { $_->[0] } $self->_extract_order_criteria ($attrs->{order_by}, $sql_maker), ], }; - # throw away empty chunks - $_ = [ map { $_ || () } @$_ ] for values %$to_scan; + # throw away empty chunks and all 2-value arrayrefs: the thinking is that these are + # bind value specs left in by the sloppy renderer above. It is ok to do this + # at this point, since we are going to end up rewriting this crap anyway + for my $v (values %$to_scan) { + my @nv; + for (@$v) { + next if ( + ! defined $_ + or + ( + ref $_ eq 'ARRAY' + and + ( @$_ == 0 or @$_ == 2 ) + ) + ); + + if (ref $_) { + require Data::Dumper::Concise; + $self->throw_exception("Unexpected ref in scan-plan: " . Data::Dumper::Concise::Dumper($v) ); + } + + push @nv, $_; + } - # first loop through all fully qualified columns and get the corresponding + $v = \@nv; + } + + # kill all selectors which look like a proper subquery + # this is a sucky heuristic *BUT* - if we get it wrong the query will simply + # fail to run, so we are relatively safe + $to_scan->{selecting} = [ grep { + $_ !~ / \A \s* \( \s* SELECT \s+ .+? \s+ FROM \s+ .+? \) \s* \z /xsi + } @{ $to_scan->{selecting} || [] } ]; + + # first see if we have any exact matches (qualified or unqualified) + for my $type (keys %$to_scan) { + for my $piece (@{$to_scan->{$type}}) { + if ($colinfo->{$piece} and my $alias = $colinfo->{$piece}{-source_alias}) { + $aliases_by_type->{$type}{$alias} ||= { -parents => $alias_list->{$alias}{-join_path}||[] }; + $aliases_by_type->{$type}{$alias}{-seen_columns}{$colinfo->{$piece}{-fq_colname}} = $piece; + } + } + } + + # now loop through all fully qualified columns and get the corresponding # alias (should work even if they are in scalarrefs) for my $alias (keys %$alias_list) { my $al_re = qr/ - $lquote $alias $rquote $sep + $lquote $alias $rquote $sep (?: $lquote ([^$rquote]+) $rquote )? | - \b $alias \. + \b $alias \. ([^\s\)\($rquote]+)? /x; for my $type (keys %$to_scan) { for my $piece (@{$to_scan->{$type}}) { - $aliases_by_type->{$type}{$alias} ||= $alias_list->{$alias}{-join_path}||[] - if ($piece =~ $al_re); + if (my @matches = $piece =~ /$al_re/g) { + $aliases_by_type->{$type}{$alias} ||= { -parents => $alias_list->{$alias}{-join_path}||[] }; + $aliases_by_type->{$type}{$alias}{-seen_columns}{"$alias.$_"} = "$alias.$_" + for grep { defined $_ } @matches; + } } } } @@ -351,13 +505,15 @@ sub _resolve_aliastypes_from_select_args { for my $col (keys %$colinfo) { next if $col =~ / \. /x; # if column is qualified it was caught by the above - my $col_re = qr/ $lquote $col $rquote /x; + my $col_re = qr/ $lquote ($col) $rquote /x; for my $type (keys %$to_scan) { for my $piece (@{$to_scan->{$type}}) { - if ($piece =~ $col_re) { + if ( my @matches = $piece =~ /$col_re/g) { my $alias = $colinfo->{$col}{-source_alias}; - $aliases_by_type->{$type}{$alias} ||= $alias_list->{$alias}{-join_path}||[]; + $aliases_by_type->{$type}{$alias} ||= { -parents => $alias_list->{$alias}{-join_path}||[] }; + $aliases_by_type->{$type}{$alias}{-seen_columns}{"$alias.$_"} = $_ + for grep { defined $_ } @matches; } } } @@ -366,76 +522,166 @@ sub _resolve_aliastypes_from_select_args { # Add any non-left joins to the restriction list (such joins are indeed restrictions) for my $j (values %$alias_list) { my $alias = $j->{-alias} or next; - $aliases_by_type->{restricting}{$alias} ||= $j->{-join_path}||[] if ( + $aliases_by_type->{restricting}{$alias} ||= { -parents => $j->{-join_path}||[] } if ( (not $j->{-join_type}) or ($j->{-join_type} !~ /^left (?: \s+ outer)? $/xi) ); } + for (keys %$aliases_by_type) { + delete $aliases_by_type->{$_} unless keys %{$aliases_by_type->{$_}}; + } + return $aliases_by_type; } -# This is the engine behind { distinct => 1 } +# This is the engine behind { distinct => 1 } and the general +# complex prefetch grouper sub _group_over_selection { - my ($self, $from, $select, $order_by) = @_; + my ($self, $attrs) = @_; - my $rs_column_list = $self->_resolve_column_info ($from); + my $colinfos = $self->_resolve_column_info ($attrs->{from}); my (@group_by, %group_index); # the logic is: if it is a { func => val } we assume an aggregate, # otherwise if \'...' or \[...] we assume the user knows what is # going on thus group over it - for (@$select) { + for (@{$attrs->{select}}) { if (! ref($_) or ref ($_) ne 'HASH' ) { push @group_by, $_; $group_index{$_}++; - if ($rs_column_list->{$_} and $_ !~ /\./ ) { + if ($colinfos->{$_} and $_ !~ /\./ ) { # add a fully qualified version as well - $group_index{"$rs_column_list->{$_}{-source_alias}.$_"}++; + $group_index{"$colinfos->{$_}{-source_alias}.$_"}++; } } } + my @order_by = $self->_extract_order_criteria($attrs->{order_by}) + or return (\@group_by, $attrs->{order_by}); + # add any order_by parts that are not already present in the group_by - # we need to be careful not to add any named functions/aggregates - # i.e. order_by => [ ... { count => 'foo' } ... ] - my @leftovers; - for ($self->_extract_order_criteria($order_by)) { + # to maintain SQL cross-compatibility and general sanity + # + # also in case the original selection is *not* unique, or in case part + # of the ORDER BY refers to a multiplier - we will need to replace the + # skipped order_by elements with their MIN/MAX equivalents as to maintain + # the proper overall order without polluting the group criteria (and + # possibly changing the outcome entirely) + + my ($leftovers, $sql_maker, @new_order_by, $order_chunks, $aliastypes); + + my $group_already_unique = $self->_columns_comprise_identifying_set($colinfos, \@group_by); + + for my $o_idx (0 .. $#order_by) { + + # if the chunk is already a min/max function - there is nothing left to touch + next if $order_by[$o_idx][0] =~ /^ (?: min | max ) \s* \( .+ \) $/ix; + # only consider real columns (for functions the user got to do an explicit group_by) - if (@$_ != 1) { - push @leftovers, $_; - next; - } - my $chunk = $_->[0]; - my $colinfo = $rs_column_list->{$chunk} or do { - push @leftovers, $_; - next; - }; + my $chunk_ci; + if ( + @{$order_by[$o_idx]} != 1 + or + # only declare an unknown *plain* identifier as "leftover" if we are called with + # aliastypes to examine. If there are none - we are still in _resolve_attrs, and + # can just assume the user knows what they want + ( ! ( $chunk_ci = $colinfos->{$order_by[$o_idx][0]} ) and $attrs->{_aliastypes} ) + ) { + push @$leftovers, $order_by[$o_idx][0]; + } + + next unless $chunk_ci; + + # no duplication of group criteria + next if $group_index{$chunk_ci->{-fq_colname}}; + + $aliastypes ||= ( + $attrs->{_aliastypes} + or + $self->_resolve_aliastypes_from_select_args({ + from => $attrs->{from}, + order_by => $attrs->{order_by}, + }) + ) if $group_already_unique; + + # check that we are not ordering by a multiplier (if a check is requested at all) + if ( + $group_already_unique + and + ! $aliastypes->{multiplying}{$chunk_ci->{-source_alias}} + and + ! $aliastypes->{premultiplied}{$chunk_ci->{-source_alias}} + ) { + push @group_by, $chunk_ci->{-fq_colname}; + $group_index{$chunk_ci->{-fq_colname}}++ + } + else { + # We need to order by external columns without adding them to the group + # (eiehter a non-unique selection, or a multi-external) + # + # This doesn't really make sense in SQL, however from DBICs point + # of view is rather valid (e.g. order the leftmost objects by whatever + # criteria and get the offset/rows many). There is a way around + # this however in SQL - we simply tae the direction of each piece + # of the external order and convert them to MIN(X) for ASC or MAX(X) + # for DESC, and group_by the root columns. The end result should be + # exactly what we expect + + # FIXME - this code is a joke, will need to be completely rewritten in + # the DQ branch. But I need to push a POC here, otherwise the + # pesky tests won't pass + # wrap any part of the order_by that "responds" to an ordering alias + # into a MIN/MAX + $sql_maker ||= $self->sql_maker; + $order_chunks ||= [ + map { ref $_ eq 'ARRAY' ? $_ : [ $_ ] } $sql_maker->_order_by_chunks($attrs->{order_by}) + ]; + + my ($chunk, $is_desc) = $sql_maker->_split_order_chunk($order_chunks->[$o_idx][0]); - $chunk = "$colinfo->{-source_alias}.$chunk" if $chunk !~ /\./; - push @group_by, $chunk unless $group_index{$chunk}++; + $new_order_by[$o_idx] = \[ + sprintf( '%s( %s )%s', + ($is_desc ? 'MAX' : 'MIN'), + $chunk, + ($is_desc ? ' DESC' : ''), + ), + @ {$order_chunks->[$o_idx]} [ 1 .. $#{$order_chunks->[$o_idx]} ] + ]; + } } - return wantarray - ? (\@group_by, (@leftovers ? \@leftovers : undef) ) - : \@group_by - ; + $self->throw_exception ( sprintf + 'Unable to programatically derive a required group_by from the supplied ' + . 'order_by criteria. To proceed either add an explicit group_by, or ' + . 'simplify your order_by to only include plain columns ' + . '(supplied order_by: %s)', + join ', ', map { "'$_'" } @$leftovers, + ) if $leftovers; + + # recreate the untouched order parts + if (@new_order_by) { + $new_order_by[$_] ||= \ $order_chunks->[$_] for ( 0 .. $#$order_chunks ); + } + + return ( + \@group_by, + (@new_order_by ? \@new_order_by : $attrs->{order_by} ), # same ref as original == unchanged + ); } sub _resolve_ident_sources { my ($self, $ident) = @_; my $alias2source = {}; - my $rs_alias; # the reason this is so contrived is that $ident may be a {from} # structure, specifying multiple tables to join if ( blessed $ident && $ident->isa("DBIx::Class::ResultSource") ) { # this is compat mode for insert/update/delete which do not deal with aliases $alias2source->{me} = $ident; - $rs_alias = 'me'; } elsif (ref $ident eq 'ARRAY') { @@ -443,7 +689,6 @@ sub _resolve_ident_sources { my $tabinfo; if (ref $_ eq 'HASH') { $tabinfo = $_; - $rs_alias = $tabinfo->{-alias}; } if (ref $_ eq 'ARRAY' and ref $_->[0] eq 'HASH') { $tabinfo = $_->[0]; @@ -454,7 +699,7 @@ sub _resolve_ident_sources { } } - return ($alias2source, $rs_alias); + return $alias2source; } # Takes $ident, \@column_names @@ -466,7 +711,10 @@ sub _resolve_ident_sources { # for all sources sub _resolve_column_info { my ($self, $ident, $colnames) = @_; - my ($alias2src, $root_alias) = $self->_resolve_ident_sources($ident); + + return {} if $colnames and ! @$colnames; + + my $alias2src = $self->_resolve_ident_sources($ident); my (%seen_cols, @auto_colnames); @@ -536,31 +784,9 @@ sub _resolve_column_info { sub _inner_join_to_node { my ($self, $from, $alias) = @_; - # subqueries and other oddness are naturally not supported - return $from if ( - ref $from ne 'ARRAY' - || - @$from <= 1 - || - ref $from->[0] ne 'HASH' - || - ! $from->[0]{-alias} - || - $from->[0]{-alias} eq $alias # this last bit means $alias is the head of $from - nothing to do - ); - - # find the current $alias in the $from structure - my $switch_branch; - JOINSCAN: - for my $j (@{$from}[1 .. $#$from]) { - if ($j->[0]{-alias} eq $alias) { - $switch_branch = $j->[0]{-join_path}; - last JOINSCAN; - } - } + my $switch_branch = $self->_find_join_path_to_node($from, $alias); - # something else went quite wrong - return $from unless $switch_branch; + return $from unless @{$switch_branch||[]}; # So it looks like we will have to switch some stuff around. # local() is useless here as we will be leaving the scope @@ -588,74 +814,53 @@ sub _inner_join_to_node { return \@new_from; } -# yet another atrocity: attempt to extract all columns from a -# where condition by hooking _quote -sub _extract_condition_columns { - my ($self, $cond, $sql_maker) = @_; - - return [] unless $cond; - - $sql_maker ||= $self->{_sql_ident_capturer} ||= do { - # FIXME - replace with a Moo trait - my $orig_sm_class = ref $self->sql_maker; - my $smic_class = "${orig_sm_class}::_IdentCapture_"; - - unless ($smic_class->isa('SQL::Abstract')) { - - no strict 'refs'; - *{"${smic_class}::_quote"} = subname "${smic_class}::_quote" => sub { - my ($self, $ident) = @_; - if (ref $ident eq 'SCALAR') { - $ident = $$ident; - my $storage_quotes = $self->sql_quote_char || '"'; - my ($ql, $qr) = map - { quotemeta $_ } - (ref $storage_quotes eq 'ARRAY' ? @$storage_quotes : ($storage_quotes) x 2 ) - ; - - while ($ident =~ / - $ql (\w+) $qr - | - ([\w\.]+) - /xg) { - $self->{_captured_idents}{$1||$2}++; - } - } - else { - $self->{_captured_idents}{$ident}++; - } - return $ident; - }; - - *{"${smic_class}::_get_captured_idents"} = subname "${smic_class}::_get_captures" => sub { - (delete shift->{_captured_idents}) || {}; - }; +sub _find_join_path_to_node { + my ($self, $from, $target_alias) = @_; - $self->inject_base ($smic_class, $orig_sm_class); - - } + # subqueries and other oddness are naturally not supported + return undef if ( + ref $from ne 'ARRAY' + || + ref $from->[0] ne 'HASH' + || + ! defined $from->[0]{-alias} + ); - $smic_class->new(); - }; + # no path - the head is the alias + return [] if $from->[0]{-alias} eq $target_alias; - $sql_maker->_recurse_where($cond); + for my $i (1 .. $#$from) { + return $from->[$i][0]{-join_path} if ( ($from->[$i][0]{-alias}||'') eq $target_alias ); + } - return [ sort keys %{$sql_maker->_get_captured_idents} ]; + # something else went quite wrong + return undef; } sub _extract_order_criteria { my ($self, $order_by, $sql_maker) = @_; my $parser = sub { - my ($sql_maker, $order_by) = @_; + my ($sql_maker, $order_by, $orig_quote_chars) = @_; return scalar $sql_maker->_order_by_chunks ($order_by) unless wantarray; + my ($lq, $rq, $sep) = map { quotemeta($_) } ( + ($orig_quote_chars ? @$orig_quote_chars : $sql_maker->_quote_chars), + $sql_maker->name_sep + ); + my @chunks; for ($sql_maker->_order_by_chunks ($order_by) ) { - my $chunk = ref $_ ? $_ : [ $_ ]; - $chunk->[0] =~ s/\s+ (?: ASC|DESC ) \s* $//ix; + my $chunk = ref $_ ? [ @$_ ] : [ $_ ]; + ($chunk->[0]) = $sql_maker->_split_order_chunk($chunk->[0]); + + # order criteria may have come back pre-quoted (literals and whatnot) + # this is fragile, but the best we can currently do + $chunk->[0] =~ s/^ $lq (.+?) $rq $sep $lq (.+?) $rq $/"$1.$2"/xe + or $chunk->[0] =~ s/^ $lq (.+) $rq $/$1/x; + push @chunks, $chunk; } @@ -667,67 +872,395 @@ sub _extract_order_criteria { } else { $sql_maker = $self->sql_maker; + + # pass these in to deal with literals coming from + # the user or the deep guts of prefetch + my $orig_quote_chars = [$sql_maker->_quote_chars]; + local $sql_maker->{quote_char}; - return $parser->($sql_maker, $order_by); + return $parser->($sql_maker, $order_by, $orig_quote_chars); } } sub _order_by_is_stable { my ($self, $ident, $order_by, $where) = @_; - my $colinfo = $self->_resolve_column_info($ident, [ - (map { $_->[0] } $self->_extract_order_criteria($order_by)), - $where ? @{$self->_extract_fixed_condition_columns($where)} :(), - ]); + my @cols = ( + ( map { $_->[0] } $self->_extract_order_criteria($order_by) ), + ( $where ? keys %{ $self->_extract_fixed_condition_columns($where) } : () ), + ) or return 0; + + my $colinfo = $self->_resolve_column_info($ident, \@cols); + + return keys %$colinfo + ? $self->_columns_comprise_identifying_set( $colinfo, \@cols ) + : 0 + ; +} - return undef unless keys %$colinfo; +sub _columns_comprise_identifying_set { + my ($self, $colinfo, $columns) = @_; my $cols_per_src; - $cols_per_src->{$_->{-source_alias}}{$_->{-colname}} = $_ for values %$colinfo; + $cols_per_src -> {$_->{-source_alias}} -> {$_->{-colname}} = $_ + for grep { defined $_ } @{$colinfo}{@$columns}; for (values %$cols_per_src) { my $src = (values %$_)[0]->{-result_source}; return 1 if $src->_identifying_column_set($_); } - return undef; + return 0; } -# returns an arrayref of column names which *definitely* have som -# sort of non-nullable equality requested in the given condition -# specification. This is used to figure out if a resultset is -# constrained to a column which is part of a unique constraint, -# which in turn allows us to better predict how ordering will behave -# etc. +# this is almost similar to _order_by_is_stable, except it takes +# a single rsrc, and will succeed only if the first portion of the order +# by is stable. +# returns that portion as a colinfo hashref on success +sub _extract_colinfo_of_stable_main_source_order_by_portion { + my ($self, $attrs) = @_; + + my $nodes = $self->_find_join_path_to_node($attrs->{from}, $attrs->{alias}); + + return unless defined $nodes; + + my @ord_cols = map + { $_->[0] } + ( $self->_extract_order_criteria($attrs->{order_by}) ) + ; + return unless @ord_cols; + + my $valid_aliases = { map { $_ => 1 } ( + $attrs->{from}[0]{-alias}, + map { values %$_ } @$nodes, + ) }; + + my $colinfos = $self->_resolve_column_info($attrs->{from}); + + my ($colinfos_to_return, $seen_main_src_cols); + + for my $col (@ord_cols) { + # if order criteria is unresolvable - there is nothing we can do + my $colinfo = $colinfos->{$col} or last; + + # if we reached the end of the allowed aliases - also nothing we can do + last unless $valid_aliases->{$colinfo->{-source_alias}}; + + $colinfos_to_return->{$col} = $colinfo; + + $seen_main_src_cols->{$colinfo->{-colname}} = 1 + if $colinfo->{-source_alias} eq $attrs->{alias}; + } + + # FIXME the condition may be singling out things on its own, so we + # conceivable could come back wi "stable-ordered by nothing" + # not confient enough in the parser yet, so punt for the time being + return unless $seen_main_src_cols; + + my $main_src_fixed_cols_from_cond = [ $attrs->{where} + ? ( + map + { + ( $colinfos->{$_} and $colinfos->{$_}{-source_alias} eq $attrs->{alias} ) + ? $colinfos->{$_}{-colname} + : () + } + keys %{ $self->_extract_fixed_condition_columns($attrs->{where}) } + ) + : () + ]; + + return $attrs->{result_source}->_identifying_column_set([ + keys %$seen_main_src_cols, + @$main_src_fixed_cols_from_cond, + ]) ? $colinfos_to_return : (); +} + +# Attempts to flatten a passed in SQLA condition as much as possible towards +# a plain hashref, *without* altering its semantics. Required by +# create/populate being able to extract definitive conditions from preexisting +# resultset {where} stacks # -# this is a rudimentary, incomplete, and error-prone extractor -# however this is OK - it is conservative, and if we can not find -# something that is in fact there - the stack will recover gracefully -# Also - DQ and the mst it rode in on will save us all RSN!!! -sub _extract_fixed_condition_columns { - my ($self, $where, $nested) = @_; +# FIXME - while relatively robust, this is still imperfect, one of the first +# things to tackle with DQ +sub _collapse_cond { + my ($self, $where, $where_is_anded_array) = @_; + + if (! $where) { + return; + } + elsif ($where_is_anded_array or ref $where eq 'HASH') { + + my @pairs; + + my @pieces = $where_is_anded_array ? @$where : $where; + while (@pieces) { + my $chunk = shift @pieces; + + if (ref $chunk eq 'HASH') { + push @pairs, map { [ $_ => $chunk->{$_} ] } sort keys %$chunk; + } + elsif (ref $chunk eq 'ARRAY') { + push @pairs, [ -or => $chunk ] + if @$chunk; + } + elsif ( ! ref $chunk) { + push @pairs, [ $chunk, shift @pieces ]; + } + else { + push @pairs, [ '', $chunk ]; + } + } + + return unless @pairs; + + my @conds = $self->_collapse_cond_unroll_pairs(\@pairs) + or return; + + # Consolidate various @conds back into something more compact + my $fin; + + for my $c (@conds) { + if (ref $c ne 'HASH') { + push @{$fin->{-and}}, $c; + } + else { + for my $col (sort keys %$c) { + if (exists $fin->{$col}) { + my ($l, $r) = ($fin->{$col}, $c->{$col}); + + (ref $_ ne 'ARRAY' or !@$_) and $_ = [ -and => $_ ] for ($l, $r); + + if (@$l and @$r and $l->[0] eq $r->[0] and $l->[0] eq '-and') { + $fin->{$col} = [ -and => map { @$_[1..$#$_] } ($l, $r) ]; + } + else { + $fin->{$col} = [ -and => $fin->{$col}, $c->{$col} ]; + } + } + else { + $fin->{$col} = $c->{$col}; + } + } + } + } + + if ( ref $fin->{-and} eq 'ARRAY' and @{$fin->{-and}} == 1 ) { + my $piece = (delete $fin->{-and})->[0]; + if (ref $piece eq 'ARRAY') { + $fin->{-or} = $fin->{-or} ? [ $piece, $fin->{-or} ] : $piece; + } + elsif (! exists $fin->{''}) { + $fin->{''} = $piece; + } + } + + return $fin; + } + elsif (ref $where eq 'ARRAY') { + my @w = @$where; + + while ( @w and ( + (ref $w[0] eq 'ARRAY' and ! @{$w[0]} ) + or + (ref $w[0] eq 'HASH' and ! keys %{$w[0]}) + )) { shift @w }; - return unless ref $where eq 'HASH'; + return unless @w; - my @cols; - for my $lhs (keys %$where) { - if ($lhs =~ /^\-and$/i) { - push @cols, ref $where->{$lhs} eq 'ARRAY' - ? ( map { $self->_extract_fixed_condition_columns($_, 1) } @{$where->{$lhs}} ) - : $self->_extract_fixed_condition_columns($where->{$lhs}, 1) + if ( @w == 1 ) { + return ( ref $w[0] ) + ? $self->_collapse_cond($w[0]) + : { $w[0] => undef } ; } - elsif ($lhs !~ /^\-/) { - my $val = $where->{$lhs}; + elsif ( @w == 2 and ! ref $w[0]) { + if ( ( $w[0]||'' ) =~ /^\-and$/i ) { + return (ref $w[1] eq 'HASH' or ref $w[1] eq 'ARRAY') + ? $self->_collapse_cond($w[1], (ref $w[1] eq 'ARRAY') ) + : $self->throw_exception("Unsupported top-level op/arg pair: [ $w[0] => $w[1] ]") + ; + } + else { + return $self->_collapse_cond({ @w }); + } + } + else { + return { -or => \@w }; + } + } + else { + # not a hash not an array + return { '' => $where }; + } - push @cols, $lhs if (defined $val and ( - ! ref $val - or - (ref $val eq 'HASH' and keys %$val == 1 and defined $val->{'='}) - )); + die 'should not get here'; +} + +sub _collapse_cond_unroll_pairs { + my ($self, $pairs) = @_; + + my @conds; + + while (@$pairs) { + my ($lhs, $rhs) = @{ shift @$pairs }; + + if ($lhs eq '') { + push @conds, $self->_collapse_cond($rhs); + } + elsif ( $lhs =~ /^\-and$/i ) { + push @conds, $self->_collapse_cond($rhs, (ref $rhs eq 'ARRAY')); + } + elsif ( $lhs =~ /^\-or$/i ) { + push @conds, $self->_collapse_cond( + (ref $rhs eq 'HASH') ? [ map { $_ => $rhs->{$_} } sort keys %$rhs ] : $rhs + ); + } + else { + if (ref $rhs eq 'HASH' and ! keys %$rhs) { + # FIXME - SQLA seems to be doing... nothing...? + } + elsif (ref $rhs eq 'HASH' and keys %$rhs == 1 and exists $rhs->{-ident}) { + push @conds, { $lhs => { '=', $rhs } }; + } + elsif (ref $rhs eq 'HASH' and keys %$rhs == 1 and exists $rhs->{-value} and is_plain_value $rhs->{-value}) { + push @conds, { $lhs => $rhs->{-value} }; + } + elsif (ref $rhs eq 'HASH' and keys %$rhs == 1 and exists $rhs->{'='}) { + if( is_literal_value $rhs->{'='}) { + push @conds, { $lhs => $rhs }; + } + else { + for my $p ($self->_collapse_cond_unroll_pairs([ [ $lhs => $rhs->{'='} ] ])) { + + # extra sanity check + if (keys %$p > 1) { + require Data::Dumper::Concise; + local $Data::Dumper::Deepcopy = 1; + $self->throw_exception( + "Internal error: unexpected collapse unroll:" + . Data::Dumper::Concise::Dumper { in => { $lhs => $rhs }, out => $p } + ); + } + + my ($l, $r) = %$p; + + push @conds, ( ! length ref $r or is_plain_value($r) ) + ? { $l => $r } + : { $l => { '=' => $r } } + ; + } + } + } + elsif (ref $rhs eq 'ARRAY') { + # some of these conditionals encounter multi-values - roll them out using + # an unshift, which will cause extra looping in the while{} above + if (! @$rhs ) { + push @conds, { $lhs => [] }; + } + elsif ( ($rhs->[0]||'') =~ /^\-(?:and|or)$/i ) { + $self->throw_exception("Value modifier not followed by any values: $lhs => [ $rhs->[0] ] ") + if @$rhs == 1; + + if( $rhs->[0] =~ /^\-and$/i ) { + unshift @$pairs, map { [ $lhs => $_ ] } @{$rhs}[1..$#$rhs]; + } + # if not an AND then it's an OR + elsif(@$rhs == 2) { + unshift @$pairs, [ $lhs => $rhs->[1] ]; + } + else { + push @conds, { $lhs => $rhs }; + } + } + elsif (@$rhs == 1) { + unshift @$pairs, [ $lhs => $rhs->[0] ]; + } + else { + push @conds, { $lhs => $rhs }; + } + } + else { + push @conds, { $lhs => $rhs }; + } + } + } + + return @conds; +} + +# Analyzes a given condition and attempts to extract all columns +# with a definitive fixed-condition criteria. Returns a hashref +# of k/v pairs suitable to be passed to set_columns(), with a +# MAJOR CAVEAT - multi-value (contradictory) equalities are still +# represented as a reference to the UNRESOVABLE_CONDITION constant +# The reason we do this is that some codepaths only care about the +# codition being stable, as opposed to actually making sense +# +# The normal mode is used to figure out if a resultset is constrained +# to a column which is part of a unique constraint, which in turn +# allows us to better predict how ordering will behave etc. +# +# With the optional "consider_nulls" boolean argument, the function +# is instead used to infer inambiguous values from conditions +# (e.g. the inheritance of resultset conditions on new_result) +# +my $undef_marker = \ do{ my $x = 'undef' }; +sub _extract_fixed_condition_columns { + my ($self, $where, $consider_nulls) = @_; + my $where_hash = $self->_collapse_cond($_[1]); + + my $res = {}; + my ($c, $v); + for $c (keys %$where_hash) { + my $vals; + + if (!defined ($v = $where_hash->{$c}) ) { + $vals->{$undef_marker} = $v if $consider_nulls + } + elsif ( + ref $v eq 'HASH' + and + keys %$v == 1 + ) { + if (exists $v->{-value}) { + if (defined $v->{-value}) { + $vals->{$v->{-value}} = $v->{-value} + } + elsif( $consider_nulls ) { + $vals->{$undef_marker} = $v->{-value}; + } + } + # do not need to check for plain values - _collapse_cond did it for us + elsif(ref $v->{'='} and is_literal_value($v->{'='}) ) { + $vals->{$v->{'='}} = $v->{'='}; + } + } + elsif ( + ! length ref $v + or + is_plain_value ($v) + ) { + $vals->{$v} = $v; + } + elsif (ref $v eq 'ARRAY' and ($v->[0]||'') eq '-and') { + for ( @{$v}[1..$#$v] ) { + my $subval = $self->_extract_fixed_condition_columns({ $c => $_ }, 'consider nulls'); # always fish nulls out on recursion + next unless exists $subval->{$c}; # didn't find anything + $vals->{defined $subval->{$c} ? $subval->{$c} : $undef_marker} = $subval->{$c}; + } + } + + if (keys %$vals == 1) { + ($res->{$c}) = (values %$vals) + unless !$consider_nulls and exists $vals->{$undef_marker}; + } + elsif (keys %$vals > 1) { + $res->{$c} = UNRESOLVABLE_CONDITION; } } - return $nested ? @cols : \@cols; + + $res; } 1;