X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FDBIx%2FClass%2FStorage%2FDBIHacks.pm;h=8a3cb0279ff273c6e23c686cfab15aaca214a439;hb=93d7452f38b38b66d6d8282425a928873725f43e;hp=4481a2e0a78fbf76de0cd310fd78895bd4afd9b2;hpb=7eb76996314f77de7ab9e2f346dd14a9ccc53896;p=dbsrgits%2FDBIx-Class.git diff --git a/lib/DBIx/Class/Storage/DBIHacks.pm b/lib/DBIx/Class/Storage/DBIHacks.pm index 4481a2e..8a3cb02 100644 --- a/lib/DBIx/Class/Storage/DBIHacks.pm +++ b/lib/DBIx/Class/Storage/DBIHacks.pm @@ -1,9 +1,10 @@ -package DBIx::Class::Storage::DBIHacks; +package #hide from PAUSE + DBIx::Class::Storage::DBIHacks; # # This module contains code that should never have seen the light of day, # does not belong in the Storage, or is otherwise unfit for public -# display. The arrival of SQLA2 should immediately oboslete 90% of this +# display. The arrival of SQLA2 should immediately obsolete 90% of this # use strict; @@ -12,255 +13,643 @@ use warnings; use base 'DBIx::Class::Storage'; use mro 'c3'; -use Carp::Clan qw/^DBIx::Class/; +use List::Util 'first'; +use Scalar::Util 'blessed'; +use Sub::Name 'subname'; +use namespace::clean; # -# This is the code producing joined subqueries like: -# SELECT me.*, other.* FROM ( SELECT me.* FROM ... ) JOIN other ON ... +# This code will remove non-selecting/non-restricting joins from +# {from} specs, aiding the RDBMS query optimizer # -sub _adjust_select_args_for_complex_prefetch { - my ($self, $from, $select, $where, $attrs) = @_; +sub _prune_unused_joins { + my ($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 + ); - $self->throw_exception ('Nothing to prefetch... how did we get here?!') - if not @{$attrs->{_prefetch_select}}; + my $orig_aliastypes = $self->_resolve_aliastypes_from_select_args($attrs); - $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 $new_aliastypes = { %$orig_aliastypes }; + # we will be recreating this entirely + my @reclassify = 'joining'; - # 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/; + # a grouped set will not be affected by amount of rows. Thus any + # 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}; - my $inner_attrs = { %$attrs }; - delete $inner_attrs->{$_} for qw/for collapse _prefetch_select _collapse_order_by select as/; + # nuke what will be recalculated + delete @{$new_aliastypes}{@reclassify}; + my @newfrom = $attrs->{from}[0]; # FROM head is always present - # bring over all non-collapse-induced order_by into the inner query (if any) - # the outer one will have to keep them all - delete $inner_attrs->{order_by}; - if (my $ord_cnt = @{$outer_attrs->{order_by}} - @{$outer_attrs->{_collapse_order_by}} ) { - $inner_attrs->{order_by} = [ - @{$outer_attrs->{order_by}}[ 0 .. $ord_cnt - 1] - ]; + # recalculate what we need once the multipliers are potentially gone + # ignore premultiplies, since they do not add any value to anything + my %need_joins; + for ( @{$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 %$_ } map { @{$_->{-parents}} } values %$_; } + for my $j (@{$attrs->{from}}[1..$#{$attrs->{from}}]) { + push @newfrom, $j if ( + (! defined $j->[0]{-alias}) # legacy crap + || + $need_joins{$j->[0]{-alias}} + ); + } + + # 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, $new_aliastypes ); +} + +# +# This is the code producing joined subqueries like: +# SELECT me.*, other.* FROM ( SELECT me.* FROM ... ) JOIN other ON ... +# +sub _adjust_select_args_for_complex_prefetch { + my ($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' + ); + + my $root_alias = $attrs->{alias}; + + # generate inner/outer attribute lists, remove stuff that doesn't apply + my $outer_attrs = { %$attrs }; + delete @{$outer_attrs}{qw(from bind rows offset group_by _grouped_by_distinct having)}; + + my $inner_attrs = { %$attrs }; + delete @{$inner_attrs}{qw(for collapse select as _related_results_construction)}; + + # 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 = []; - for my $i (0 .. ( @$outer_select - @{$outer_attrs->{_prefetch_select}} - 1) ) { - my $sel = $outer_select->[$i]; + $outer_attrs->{select} = [ @{$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') ? $node->[0] + : next + ; + + if ( ($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_attrs->{select}}, $sel; - push @$inner_select, $sel; + push @{$inner_attrs->{as}}, $attrs->{as}[$i]; } - # normalize a copy of $from, so it will be easier to work with further - # down (i.e. promote the initial hashref to an AoH) - $from = [ @$from ]; - $from->[0] = [ $from->[0] ]; - my %original_join_info = map { $_->[0]{-alias} => $_->[0] } (@$from); + # 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 { - # decide which parts of the join will remain in either part of - # the outer/inner query + # must use it here regardless of user requests (vastly gentler on optimizer) + local $self->{_use_join_optimizer} = 1; - # First we compose a list of which aliases are used in restrictions - # (i.e. conditions/order/grouping/etc). Since we do not have - # introspectable SQLA, we fall back to ugly scanning of raw SQL for - # WHERE, and for pieces of ORDER BY in order to determine which aliases - # need to appear in the resulting sql. - # It may not be very efficient, but it's a reasonable stop-gap - # Also unqualified column names will not be considered, but more often - # than not this is actually ok - # - # In the same loop we enumerate part of the selection aliases, as - # it requires the same sqla hack for the time being - my ($restrict_aliases, $select_aliases, $prefetch_aliases); - { - # produce stuff unquoted, so it can be scanned - my $sql_maker = $self->sql_maker; - local $sql_maker->{quote_char}; - my $sep = $self->_sql_maker_opts->{name_sep} || '.'; - $sep = "\Q$sep\E"; - - my $non_prefetch_select_sql = $sql_maker->_recurse_fields ($inner_select); - my $prefetch_select_sql = $sql_maker->_recurse_fields ($outer_attrs->{_prefetch_select}); - my $where_sql = $sql_maker->where ($where); - my $group_by_sql = $sql_maker->_order_by({ - map { $_ => $inner_attrs->{$_} } qw/group_by having/ + # 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 @non_prefetch_order_by_chunks = (map - { ref $_ ? $_->[0] : $_ } - $sql_maker->_order_by_chunks ($inner_attrs->{order_by}) + + # 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 ( + grep { $_ ne $root_alias } keys %{ $inner_aliastypes->{multiplying} || {} } + and + # if there are user-supplied groups - assume user knows wtf they are up to + ( ! $inner_aliastypes->{grouping} or $inner_attrs->{_grouped_by_distinct} ) + ) { + + 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_attrs->{from} above + # and already local()ized + $self->{_use_join_optimizer} = 0; + + # generate the subquery + $self->_select_args_to_query ( + @{$inner_attrs}{qw(from select where)}, + $inner_attrs, ); + }; + # Generate the outer from - this is relatively easy (really just replace + # the join slot with the subquery), with a major caveat - we can not + # join anything that is non-selecting (not part of the prefetch), but at + # the same time is a multi-type relationship, as it will explode the result. + # + # There are two possibilities here + # - either the join is non-restricting, in which case we simply throw it away + # - 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 - for my $alias (keys %original_join_info) { - my $seen_re = qr/\b $alias $sep/x; + # work on a shallow copy + my @orig_from = @{$attrs->{from}}; - for my $piece ($where_sql, $group_by_sql, @non_prefetch_order_by_chunks ) { - if ($piece =~ $seen_re) { - $restrict_aliases->{$alias} = 1; - } - } - if ($non_prefetch_select_sql =~ $seen_re) { - $select_aliases->{$alias} = 1; + $outer_attrs->{from} = \ my @outer_from; + + # we may not be the head + if ($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 = $outer_attrs->{_aliastypes} = + $self->_resolve_aliastypes_from_select_args({ %$outer_attrs, from => \@orig_from }); + + # unroll parents + 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 + my $may_need_outer_group_by; + while (my $j = shift @orig_from) { + my $alias = $j->[0]{-alias}; + + if ( + $outer_select_chain->{$alias} + ) { + push @outer_from, $j + } + elsif (first { $_->{$alias} } @outer_nonselecting_chains ) { + push @outer_from, $j; + $may_need_outer_group_by ||= $outer_aliastypes->{multiplying}{$alias} ? 1 : 0; + } + } + + # 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 + # 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 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_attrs; +} + +# +# I KNOW THIS SUCKS! GET SQLA2 OUT THE DOOR SO THIS CAN DIE! +# +# 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 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, $attrs ) = @_; + + $self->throw_exception ('Unable to analyze custom {from}') + 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 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} ||= { -parents => $j->{-join_path}||[] } + # not array == {from} head == can't be multiplying + if ref($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 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 + # own weird impossible character. + # Also in the case of no quoting, we need to explicitly disable + # name_sep, otherwise sorry nasty legacy syntax like + # { 'count(foo.id)' => { '>' => 3 } } will stop working >:( + local $sql_maker->{quote_char} = $sql_maker->{quote_char}; + local $sql_maker->{name_sep} = $sql_maker->{name_sep}; + + unless (defined $sql_maker->{quote_char} and length $sql_maker->{quote_char}) { + $sql_maker->{quote_char} = ["\x00", "\xFF"]; + # if we don't unset it we screw up retarded but unfortunately working + # 'MAX(foo.bar)' => { '>', 3 } + $sql_maker->{name_sep} = ''; + } + + my ($lquote, $rquote, $sep) = map { quotemeta $_ } ($sql_maker->_quote_chars, $sql_maker->name_sep); + + # generate sql chunks + my $to_scan = { + restricting => [ + $sql_maker->_recurse_where ($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 => [ + $sql_maker->_recurse_fields ($attrs->{select}), + ], + ordering => [ + map { $_->[0] } $self->_extract_order_criteria ($attrs->{order_by}, $sql_maker), + ], + }; + + # throw away empty chunks + $_ = [ map { $_ || () } @$_ ] for values %$to_scan; + + # 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}} = $piece; } + } + } - if ($prefetch_select_sql =~ $seen_re) { - $prefetch_aliases->{$alias} = 1; + # 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 (?: $lquote ([^$rquote]+) $rquote )? + | + \b $alias \. ([^\s\)\($rquote]+)? + /x; + + for my $type (keys %$to_scan) { + for my $piece (@{$to_scan->{$type}}) { + 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; + } } + } + } + # now loop through unqualified column names, and try to locate them within + # the chunks + 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; + + for my $type (keys %$to_scan) { + for my $piece (@{$to_scan->{$type}}) { + if ( my @matches = $piece =~ /$col_re/g) { + my $alias = $colinfo->{$col}{-source_alias}; + $aliases_by_type->{$type}{$alias} ||= { -parents => $alias_list->{$alias}{-join_path}||[] }; + $aliases_by_type->{$type}{$alias}{-seen_columns}{"$alias.$_"} = $_ + for grep { defined $_ } @matches; + } + } } } # Add any non-left joins to the restriction list (such joins are indeed restrictions) - for my $j (values %original_join_info) { + for my $j (values %$alias_list) { my $alias = $j->{-alias} or next; - $restrict_aliases->{$alias} = 1 if ( + $aliases_by_type->{restricting}{$alias} ||= { -parents => $j->{-join_path}||[] } if ( (not $j->{-join_type}) or ($j->{-join_type} !~ /^left (?: \s+ outer)? $/xi) ); } - # mark all join parents as mentioned - # (e.g. join => { cds => 'tracks' } - tracks will need to bring cds too ) - for my $collection ($restrict_aliases, $select_aliases) { - for my $alias (keys %$collection) { - $collection->{$_} = 1 - for (@{ $original_join_info{$alias}{-join_path} || [] }); - } - } - - # construct the inner $from for the subquery - my %inner_joins = (map { %{$_ || {}} } ($restrict_aliases, $select_aliases) ); - my @inner_from; - for my $j (@$from) { - push @inner_from, $j if $inner_joins{$j->[0]{-alias}}; + for (keys %$aliases_by_type) { + delete $aliases_by_type->{$_} unless keys %{$aliases_by_type->{$_}}; } - # if a multi-type join was needed in the subquery ("multi" is indicated by - # presence in {collapse}) - add a group_by to simulate the collapse in the subq - unless ($inner_attrs->{group_by}) { - for my $alias (keys %inner_joins) { + return $aliases_by_type; +} - # the dot comes from some weirdness in collapse - # remove after the rewrite - if ($attrs->{collapse}{".$alias"}) { - $inner_attrs->{group_by} ||= $inner_select; - last; +# This is the engine behind { distinct => 1 } and the general +# complex prefetch grouper +sub _group_over_selection { + my ($self, $attrs) = @_; + + 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 (@{$attrs->{select}}) { + if (! ref($_) or ref ($_) ne 'HASH' ) { + push @group_by, $_; + $group_index{$_}++; + if ($colinfos->{$_} and $_ !~ /\./ ) { + # add a fully qualified version as well + $group_index{"$colinfos->{$_}{-source_alias}.$_"}++; } } } - # demote the inner_from head - $inner_from[0] = $inner_from[0][0]; + my @order_by = $self->_extract_order_criteria($attrs->{order_by}) + or return (\@group_by, $attrs->{order_by}); - # generate the subquery - my $subq = $self->_select_args_to_query ( - \@inner_from, - $inner_select, - $where, - $inner_attrs, - ); + # add any order_by parts that are not already present in the group_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 $subq_joinspec = { - -alias => $attrs->{alias}, - -source_handle => $inner_from[0]{-source_handle}, - $attrs->{alias} => $subq, - }; + my ($leftovers, $sql_maker, @new_order_by, $order_chunks, $aliastypes); - # Generate the outer from - this is relatively easy (really just replace - # the join slot with the subquery), with a major caveat - we can not - # join anything that is non-selecting (not part of the prefetch), but at - # the same time is a multi-type relationship, as it will explode the result. - # - # There are two possibilities here - # - either the join is non-restricting, in which case we simply throw it away - # - 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 + my $group_already_unique = $self->_columns_comprise_identifying_set($colinfos, \@group_by); - # so first generate the outer_from, up to the substitution point - my @outer_from; - while (my $j = shift @$from) { - if ($j->[0]{-alias} eq $attrs->{alias}) { # time to swap - push @outer_from, [ - $subq_joinspec, - @{$j}[1 .. $#$j], - ]; - last; # we'll take care of what's left in $from below - } - else { - push @outer_from, $j; - } - } + for my $o_idx (0 .. $#order_by) { - # see what's left - throw away if not selecting/restricting - # also throw in a group_by if restricting to guard against - # cross-join explosions - # - while (my $j = shift @$from) { - my $alias = $j->[0]{-alias}; + # 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* \( .+ \) $/ix; - if ($select_aliases->{$alias} || $prefetch_aliases->{$alias}) { - push @outer_from, $j; + # only consider real columns (for functions the user got to do an explicit group_by) + 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]; } - elsif ($restrict_aliases->{$alias}) { - push @outer_from, $j; - # FIXME - this should be obviated by SQLA2, as I'll be able to - # have restrict_inner and restrict_outer... or something to that - # effect... I think... + next unless $chunk_ci; + + # no duplication of group criteria + next if $group_index{$chunk_ci->{-fq_colname}}; - # FIXME2 - I can't find a clean way to determine if a particular join - # is a multi - instead I am just treating everything as a potential - # explosive join (ribasushi) + $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) # - # if (my $handle = $j->[0]{-source_handle}) { - # my $rsrc = $handle->resolve; - # ... need to bail out of the following if this is not a multi, - # as it will be much easier on the db ... + # 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}) + ]; - $outer_attrs->{group_by} ||= $outer_select; - # } + my ($chunk, $is_desc) = $sql_maker->_split_order_chunk($order_chunks->[$o_idx][0]); + + $new_order_by[$o_idx] = \[ + sprintf( '%s( %s )%s', + ($is_desc ? 'MAX' : 'MIN'), + $chunk, + ($is_desc ? ' DESC' : ''), + ), + @ {$order_chunks->[$o_idx]} [ 1 .. $#{$order_chunks->[$o_idx]} ] + ]; } } - # demote the outer_from head - $outer_from[0] = $outer_from[0][0]; + $self->throw_exception ( sprintf + 'A required group_by clause could not be constructed automatically due to a complex ' + . 'order_by criteria (%s). Either order_by columns only (no functions) or construct a suitable ' + . 'group_by by hand', + join ', ', map { "'$_'" } @$leftovers, + ) if $leftovers; - # 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 - # - # 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); + # 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 $ident may be a {from} # structure, specifying multiple tables to join - if ( Scalar::Util::blessed($ident) && $ident->isa("DBIx::Class::ResultSource") ) { + 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') { @@ -268,18 +657,17 @@ 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]; } - $alias2source->{$tabinfo->{-alias}} = $tabinfo->{-source_handle}->resolve - if ($tabinfo->{-source_handle}); + $alias2source->{$tabinfo->{-alias}} = $tabinfo->{-rsrc} + if ($tabinfo->{-rsrc}); } } - return ($alias2source, $rs_alias); + return $alias2source; } # Takes $ident, \@column_names @@ -287,16 +675,13 @@ sub _resolve_ident_sources { # returns { $column_name => \%column_info, ... } # also note: this adds -result_source => $rsrc to the column info # -# usage: -# my $col_sources = $self->_resolve_column_info($ident, @column_names); +# If no columns_names are supplied returns info about *all* columns +# for all sources sub _resolve_column_info { my ($self, $ident, $colnames) = @_; - my ($alias2src, $root_alias) = $self->_resolve_ident_sources($ident); + my $alias2src = $self->_resolve_ident_sources($ident); - my $sep = $self->_sql_maker_opts->{name_sep} || '.'; - $sep = "\Q$sep\E"; - - my (%return, %seen_cols); + my (%seen_cols, @auto_colnames); # compile a global list of column names, to be able to properly # disambiguate unqualified column names (if at all possible) @@ -304,29 +689,43 @@ sub _resolve_column_info { my $rsrc = $alias2src->{$alias}; for my $colname ($rsrc->columns) { push @{$seen_cols{$colname}}, $alias; + push @auto_colnames, "$alias.$colname" unless $colnames; } } - COLUMN: + $colnames ||= [ + @auto_colnames, + grep { @{$seen_cols{$_}} == 1 } (keys %seen_cols), + ]; + + my (%return, $colinfos); foreach my $col (@$colnames) { - my ($alias, $colname) = $col =~ m/^ (?: ([^$sep]+) $sep)? (.+) $/x; + my ($source_alias, $colname) = $col =~ m/^ (?: ([^\.]+) \. )? (.+) $/x; - unless ($alias) { - # see if the column was seen exactly once (so we know which rsrc it came from) - if ($seen_cols{$colname} and @{$seen_cols{$colname}} == 1) { - $alias = $seen_cols{$colname}[0]; - } - else { - next COLUMN; - } - } + # if the column was seen exactly once - we know which rsrc it came from + $source_alias ||= $seen_cols{$colname}[0] + if ($seen_cols{$colname} and @{$seen_cols{$colname}} == 1); - my $rsrc = $alias2src->{$alias}; - $return{$col} = $rsrc && { - %{$rsrc->column_info($colname)}, + next unless $source_alias; + + my $rsrc = $alias2src->{$source_alias} + or next; + + $return{$col} = { + %{ + ( $colinfos->{$source_alias} ||= $rsrc->columns_info )->{$colname} + || + $self->throw_exception( + "No such column '$colname' on source " . $rsrc->source_name + ); + }, -result_source => $rsrc, - -source_alias => $alias, + -source_alias => $source_alias, + -fq_colname => $col eq $colname ? "$source_alias.$col" : $col, + -colname => $colname, }; + + $return{"$source_alias.$colname"} = $return{$col} if $col eq $colname; } return \%return; @@ -347,7 +746,7 @@ sub _resolve_column_info { # the top of the stack, and if not - make sure the chain is inner-joined down # to the root. # -sub _straight_join_to_node { +sub _inner_join_to_node { my ($self, $from, $alias) = @_; # subqueries and other oddness are naturally not supported @@ -379,9 +778,9 @@ sub _straight_join_to_node { # So it looks like we will have to switch some stuff around. # local() is useless here as we will be leaving the scope # anyway, and deep cloning is just too fucking expensive - # So replace the first hashref in the node arrayref manually + # So replace the first hashref in the node arrayref manually my @new_from = ($from->[0]); - my $sw_idx = { map { $_ => 1 } @$switch_branch }; + my $sw_idx = { map { (values %$_), 1 } @$switch_branch }; #there's one k/v per join-path for my $j (@{$from}[1 .. $#$from]) { my $jalias = $j->[0]{-alias}; @@ -402,4 +801,188 @@ sub _straight_join_to_node { return \@new_from; } +sub _extract_order_criteria { + my ($self, $order_by, $sql_maker) = @_; + + my $parser = sub { + my ($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]) = $sql_maker->_split_order_chunk($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, $chunk; + } + + return @chunks; + }; + + if ($sql_maker) { + return $parser->($sql_maker, $order_by); + } + 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, $orig_quote_chars); + } +} + +sub _order_by_is_stable { + my ($self, $ident, $order_by, $where) = @_; + + my @cols = ( + (map { $_->[0] } $self->_extract_order_criteria($order_by)), + $where ? @{$self->_extract_fixed_condition_columns($where)} :(), + ) or return undef; + + my $colinfo = $self->_resolve_column_info($ident, \@cols); + + return keys %$colinfo + ? $self->_columns_comprise_identifying_set( $colinfo, \@cols ) + : undef + ; +} + +sub _columns_comprise_identifying_set { + my ($self, $colinfo, $columns) = @_; + + my $cols_per_src; + $cols_per_src -> {$_->{-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; +} + +# this is almost identical to the above, except it accepts only +# 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 _main_source_order_by_portion_is_stable { + my ($self, $main_rsrc, $order_by, $where) = @_; + + die "Huh... I expect a blessed result_source..." + if ref($main_rsrc) eq 'ARRAY'; + + my @ord_cols = map + { $_->[0] } + ( $self->_extract_order_criteria($order_by) ) + ; + return unless @ord_cols; + + my $colinfos = $self->_resolve_column_info($main_rsrc); + + for (0 .. $#ord_cols) { + if ( + ! $colinfos->{$ord_cols[$_]} + or + $colinfos->{$ord_cols[$_]}{-result_source} != $main_rsrc + ) { + $#ord_cols = $_ - 1; + last; + } + } + + # we just truncated it above + return unless @ord_cols; + + my $order_portion_ci = { map { + $colinfos->{$_}{-colname} => $colinfos->{$_}, + $colinfos->{$_}{-fq_colname} => $colinfos->{$_}, + } @ord_cols }; + + # since all we check here are the start of the order_by belonging to the + # top level $rsrc, a present identifying set will mean that the resultset + # is ordered by its leftmost table in a stable manner + # + # RV of _identifying_column_set contains unqualified names only + my $unqualified_idset = $main_rsrc->_identifying_column_set({ + ( $where ? %{ + $self->_resolve_column_info( + $main_rsrc, $self->_extract_fixed_condition_columns($where) + ) + } : () ), + %$order_portion_ci + }) or return; + + my $ret_info; + my %unqualified_idcols_from_order = map { + $order_portion_ci->{$_} ? ( $_ => $order_portion_ci->{$_} ) : () + } @$unqualified_idset; + + # extra optimization - cut the order_by at the end of the identifying set + # (just in case the user was stupid and overlooked the obvious) + for my $i (0 .. $#ord_cols) { + my $col = $ord_cols[$i]; + my $unqualified_colname = $order_portion_ci->{$col}{-colname}; + $ret_info->{$col} = { %{$order_portion_ci->{$col}}, -idx_in_order_subset => $i }; + delete $unqualified_idcols_from_order{$ret_info->{$col}{-colname}}; + + # we didn't reach the end of the identifying portion yet + return $ret_info unless keys %unqualified_idcols_from_order; + } + + die 'How did we get here...'; +} + +# returns an arrayref of column names which *definitely* have some +# sort of non-nullable equality requested in the given condition +# specification. This is used to figure out if a resultset is +# constrained to a column which is part of a unique constraint, +# which in turn allows us to better predict how ordering will behave +# etc. +# +# this is a rudimentary, incomplete, and error-prone extractor +# however this is OK - it is conservative, and if we can not find +# something that is in fact there - the stack will recover gracefully +# Also - DQ and the mst it rode in on will save us all RSN!!! +sub _extract_fixed_condition_columns { + my ($self, $where) = @_; + + return unless ref $where eq 'HASH'; + + my @cols; + for my $lhs (keys %$where) { + if ($lhs =~ /^\-and$/i) { + push @cols, ref $where->{$lhs} eq 'ARRAY' + ? ( map { @{ $self->_extract_fixed_condition_columns($_) } } @{$where->{$lhs}} ) + : @{ $self->_extract_fixed_condition_columns($where->{$lhs}) } + ; + } + elsif ($lhs !~ /^\-/) { + my $val = $where->{$lhs}; + + push @cols, $lhs if (defined $val and ( + ! ref $val + or + (ref $val eq 'HASH' and keys %$val == 1 and defined $val->{'='}) + )); + } + } + return \@cols; +} + 1;