1 package #hide from PAUSE
2 DBIx::Class::Storage::DBIHacks;
5 # This module contains code that should never have seen the light of day,
6 # does not belong in the Storage, or is otherwise unfit for public
7 # display. The arrival of SQLA2 should immediately obsolete 90% of this
13 use base 'DBIx::Class::Storage';
16 use List::Util 'first';
17 use Scalar::Util 'blessed';
18 use Sub::Name 'subname';
19 use Data::Query::ExprHelpers;
23 # This code will remove non-selecting/non-restricting joins from
24 # {from} specs, aiding the RDBMS query optimizer
26 sub _prune_unused_joins {
28 my ($from, $select, $where, $attrs) = @_;
30 return $from unless $self->_use_join_optimizer;
32 if (ref $from ne 'ARRAY' || ref $from->[0] ne 'HASH' || ref $from->[1] ne 'ARRAY') {
33 return $from; # only standard {from} specs are supported
36 my $aliastypes = $self->_resolve_aliastypes_from_select_args(@_);
38 my $orig_joins = delete $aliastypes->{joining};
39 my $orig_multiplying = $aliastypes->{multiplying};
41 # a grouped set will not be affected by amount of rows. Thus any
42 # {multiplying} joins can go
43 delete $aliastypes->{multiplying}
44 if $attrs->{_force_prune_multiplying_joins} or $attrs->{group_by};
46 my @newfrom = $from->[0]; # FROM head is always present
50 for (values %$aliastypes) {
51 # add all requested aliases
52 $need_joins{$_} = 1 for keys %$_;
54 # add all their parents (as per joinpath which is an AoH { table => alias })
55 $need_joins{$_} = 1 for map { values %$_ } map { @{$_->{-parents}} } values %$_;
58 for my $j (@{$from}[1..$#$from]) {
59 push @newfrom, $j if (
60 (! defined $j->[0]{-alias}) # legacy crap
62 $need_joins{$j->[0]{-alias}}
67 multiplying => { map { $need_joins{$_} ? ($_ => $orig_multiplying->{$_}) : () } keys %$orig_multiplying },
69 joining => { map { $_ => $orig_joins->{$_} } keys %need_joins },
74 # This is the code producing joined subqueries like:
75 # SELECT me.*, other.* FROM ( SELECT me.* FROM ... ) JOIN other ON ...
77 sub _adjust_select_args_for_complex_prefetch {
78 my ($self, $from, $select, $where, $attrs) = @_;
80 $self->throw_exception ('Complex prefetches are not supported on resultsets with a custom from attribute')
81 if (ref $from ne 'ARRAY' || ref $from->[0] ne 'HASH' || ref $from->[1] ne 'ARRAY');
83 my $root_alias = $attrs->{alias};
85 # generate inner/outer attribute lists, remove stuff that doesn't apply
86 my $outer_attrs = { %$attrs };
87 delete @{$outer_attrs}{qw(where bind rows offset group_by _grouped_by_distinct having)};
89 my $inner_attrs = { %$attrs };
90 delete @{$inner_attrs}{qw(from for collapse select as _related_results_construction)};
92 # there is no point of ordering the insides if there is no limit
93 delete $inner_attrs->{order_by} if (
94 delete $inner_attrs->{_order_is_artificial}
96 ! $inner_attrs->{rows}
99 # generate the inner/outer select lists
100 # for inside we consider only stuff *not* brought in by the prefetch
101 # on the outside we substitute any function for its alias
102 my $outer_select = [ @$select ];
105 my ($root_node, $root_node_offset);
107 for my $i (0 .. $#$from) {
108 my $node = $from->[$i];
109 my $h = (ref $node eq 'HASH') ? $node
110 : (ref $node eq 'ARRAY' and ref $node->[0] eq 'HASH') ? $node->[0]
114 if ( ($h->{-alias}||'') eq $root_alias and $h->{-rsrc} ) {
116 $root_node_offset = $i;
121 $self->throw_exception ('Complex prefetches are not supported on resultsets with a custom from attribute')
124 # use the heavy duty resolver to take care of aliased/nonaliased naming
125 my $colinfo = $self->_resolve_column_info($from);
126 my $selected_root_columns;
128 for my $i (0 .. $#$outer_select) {
129 my $sel = $outer_select->[$i];
132 $colinfo->{$sel} and $colinfo->{$sel}{-source_alias} ne $root_alias
135 if (ref $sel eq 'HASH' ) {
136 $sel->{-as} ||= $attrs->{as}[$i];
137 $outer_select->[$i] = join ('.', $root_alias, ($sel->{-as} || "inner_column_$i") );
139 elsif (! ref $sel and my $ci = $colinfo->{$sel}) {
140 $selected_root_columns->{$ci->{-colname}} = 1;
143 push @$inner_select, $sel;
145 push @{$inner_attrs->{as}}, $attrs->{as}[$i];
148 # We will need to fetch all native columns in the inner subquery, which may
149 # be a part of an *outer* join condition, or an order_by (which needs to be
151 # We can not just fetch everything because a potential has_many restricting
152 # join collapse *will not work* on heavy data types.
153 my $connecting_aliastypes = $self->_resolve_aliastypes_from_select_args(
160 for (sort map { keys %{$_->{-seen_columns}||{}} } map { values %$_ } values %$connecting_aliastypes) {
161 my $ci = $colinfo->{$_} or next;
163 $ci->{-source_alias} eq $root_alias
165 ! $selected_root_columns->{$ci->{-colname}}++
167 # adding it to both to keep limits not supporting dark selectors happy
168 push @$inner_select, $ci->{-fq_colname};
169 push @{$inner_attrs->{as}}, $ci->{-fq_colname};
173 # construct the inner $from and lock it in a subquery
174 # we need to prune first, because this will determine if we need a group_by below
175 # throw away all non-selecting, non-restricting multijoins
176 # (since we def. do not care about multiplication those inside the subquery)
177 my $inner_subq = do {
179 # must use it here regardless of user requests
180 local $self->{_use_join_optimizer} = 1;
182 # throw away multijoins since we def. do not care about those inside the subquery
183 my ($inner_from, $inner_aliastypes) = $self->_prune_unused_joins ($from, $inner_select, $where, {
184 %$inner_attrs, _force_prune_multiplying_joins => 1
187 # uh-oh a multiplier (which is not us) left in, this is a problem
189 $inner_aliastypes->{multiplying}
191 # if there are user-supplied groups - assume user knows wtf they are up to
192 ( ! $inner_aliastypes->{grouping} or $inner_attrs->{_grouped_by_distinct} )
194 my @multipliers = grep { $_ ne $root_alias } keys %{$inner_aliastypes->{multiplying}}
197 # if none of the multipliers came from an order_by (guaranteed to have been combined
198 # with a limit) - easy - just slap a group_by to simulate a collapse and be on our way
200 ! $inner_aliastypes->{ordering}
202 ! first { $inner_aliastypes->{ordering}{$_} } @multipliers
205 my $unprocessed_order_chunks;
206 ($inner_attrs->{group_by}, $unprocessed_order_chunks) = $self->_group_over_selection ({
209 select => $inner_select,
212 $self->throw_exception (
213 'A required group_by clause could not be constructed automatically due to a complex '
214 . 'order_by criteria. Either order_by columns only (no functions) or construct a suitable '
216 ) if $unprocessed_order_chunks;
219 # We need to order by external columns and group at the same time
220 # so we can calculate the proper limit
221 # This doesn't really make sense in SQL, however from DBICs point
222 # of view is rather valid (order the leftmost objects by whatever
223 # criteria and get the offset/rows many). There is a way around
224 # this however in SQL - we simply tae the direction of each piece
225 # of the foreign order and convert them to MIN(X) for ASC or MAX(X)
226 # for DESC, and group_by the root columns. The end result should be
227 # exactly what we expect
229 # supplement the main selection with pks if not already there,
230 # as they will have to be a part of the group_by to collapse
232 my $cur_sel = { map { $_ => 1 } @$inner_select };
234 my @pks = map { "$root_alias.$_" } $root_node->{-rsrc}->primary_columns
235 or $self->throw_exception( sprintf
236 'Unable to perform complex limited prefetch off %s without declared primary key',
237 $root_node->{-rsrc}->source_name,
240 push @$inner_select, $col
241 unless $cur_sel->{$col}++;
244 # wrap any part of the order_by that "responds" to an ordering alias
246 # FIXME - this code is a joke, will need to be completely rewritten in
247 # the DQ branch. But I need to push a POC here, otherwise the
248 # pesky tests won't pass
249 my $sql_maker = $self->sql_maker;
250 my ($lquote, $rquote, $sep) = map { quotemeta $_ } ($sql_maker->_quote_chars, $sql_maker->name_sep);
251 my $own_re = qr/ $lquote \Q$root_alias\E $rquote $sep | \b \Q$root_alias\E $sep /x;
252 my $inner_columns_info = $self->_resolve_column_info($inner_from);
254 my $order_dq = $sql_maker->converter
255 ->_order_by_to_dq($attrs->{order_by});
259 # loop through and replace stuff that is not "ours" with a min/max func
260 # everything is a literal at this point, since we are likely properly
262 while (is_Order($order_dq)) {
263 my ($chunk, @args) = $sql_maker->_render_dq(my $by = $order_dq->{by});
265 my $is_desc = $order_dq->{reverse};
267 push @new_order, $is_desc ? { -desc => \$by } : \$by;
269 $order_dq = $order_dq->{from};
272 next if $chunk =~ $own_re;
274 # maybe our own unqualified column
276 $lquote and $sep and $chunk =~ /^ $lquote ([^$sep]+) $rquote $/x
282 $inner_columns_info->{$ord_bit}
284 $inner_columns_info->{$ord_bit}{-source_alias} eq $root_alias
287 ($new_order[-1]) = map {
288 ($is_desc ? { -desc => $_ } : $_)
292 ($is_desc ? 'MAX' : 'MIN'),
299 $inner_attrs->{order_by} = \@new_order;
301 # do not care about leftovers here - it will be all the functions
303 ($inner_attrs->{group_by}) = $self->_group_over_selection ({
306 select => $inner_select,
311 # we already optimized $inner_from above
312 # and already local()ized
313 $self->{_use_join_optimizer} = 0;
315 # generate the subquery
316 $self->_select_args_to_query (
324 # Generate the outer from - this is relatively easy (really just replace
325 # the join slot with the subquery), with a major caveat - we can not
326 # join anything that is non-selecting (not part of the prefetch), but at
327 # the same time is a multi-type relationship, as it will explode the result.
329 # There are two possibilities here
330 # - either the join is non-restricting, in which case we simply throw it away
331 # - it is part of the restrictions, in which case we need to collapse the outer
332 # result by tackling yet another group_by to the outside of the query
334 # work on a shallow copy
339 # we may not be the head
340 if ($root_node_offset) {
341 # first generate the outer_from, up and including the substitution point
342 @outer_from = splice @$from, 0, $root_node_offset;
346 -alias => $root_alias,
347 -rsrc => $root_node->{-rsrc},
348 $root_alias => $inner_subq,
350 @{$from->[0]}[1 .. $#{$from->[0]}],
355 -alias => $root_alias,
356 -rsrc => $root_node->{-rsrc},
357 $root_alias => $inner_subq,
361 shift @$from; # what we just replaced above
363 # scan the *remaining* from spec against different attributes, and see which joins are needed
365 my $outer_aliastypes = $outer_attrs->{_aliastypes} =
366 $self->_resolve_aliastypes_from_select_args( $from, $outer_select, $where, $outer_attrs );
369 my ($outer_select_chain, @outer_nonselecting_chains) = map { +{
370 map { $_ => 1 } map { values %$_} map { @{$_->{-parents}} } values %{ $outer_aliastypes->{$_} || {} }
371 } } qw/selecting restricting grouping ordering/;
373 # see what's left - throw away if not selecting/restricting
374 # also throw in a group_by if a non-selecting multiplier,
375 # to guard against cross-join explosions
376 my $need_outer_group_by;
377 while (my $j = shift @$from) {
378 my $alias = $j->[0]{-alias};
381 $outer_select_chain->{$alias}
385 elsif (first { $_->{$alias} } @outer_nonselecting_chains ) {
386 push @outer_from, $j;
387 $need_outer_group_by ||= $outer_aliastypes->{multiplying}{$alias} ? 1 : 0;
391 if ( $need_outer_group_by and $attrs->{_grouped_by_distinct} ) {
392 my $unprocessed_order_chunks;
393 ($outer_attrs->{group_by}, $unprocessed_order_chunks) = $self->_group_over_selection ({
395 from => \@outer_from,
396 select => $outer_select,
399 $self->throw_exception (
400 'A required group_by clause could not be constructed automatically due to a complex '
401 . 'order_by criteria. Either order_by columns only (no functions) or construct a suitable '
403 ) if $unprocessed_order_chunks;
407 # This is totally horrific - the $where ends up in both the inner and outer query
408 # Unfortunately not much can be done until SQLA2 introspection arrives, and even
409 # then if where conditions apply to the *right* side of the prefetch, you may have
410 # to both filter the inner select (e.g. to apply a limit) and then have to re-filter
411 # the outer select to exclude joins you didn't want in the first place
413 # OTOH it can be seen as a plus: <ash> (notes that this query would make a DBA cry ;)
414 return (\@outer_from, $outer_select, $where, $outer_attrs);
418 # I KNOW THIS SUCKS! GET SQLA2 OUT THE DOOR SO THIS CAN DIE!
420 # Due to a lack of SQLA2 we fall back to crude scans of all the
421 # select/where/order/group attributes, in order to determine what
422 # aliases are needed to fulfill the query. This information is used
423 # throughout the code to prune unnecessary JOINs from the queries
424 # in an attempt to reduce the execution time.
425 # Although the method is pretty horrific, the worst thing that can
426 # happen is for it to fail due to some scalar SQL, which in turn will
427 # result in a vocal exception.
428 sub _resolve_aliastypes_from_select_args {
429 my ( $self, $from, $select, $where, $attrs ) = @_;
431 $self->throw_exception ('Unable to analyze custom {from}')
432 if ref $from ne 'ARRAY';
434 # what we will return
437 # see what aliases are there to work with
441 $j = $j->[0] if ref $j eq 'ARRAY';
442 my $al = $j->{-alias}
445 $alias_list->{$al} = $j;
446 $aliases_by_type->{multiplying}{$al} ||= { -parents => $j->{-join_path}||[] } if (
447 # not array == {from} head == can't be multiplying
448 ( ref($_) eq 'ARRAY' and ! $j->{-is_single} )
450 # a parent of ours is already a multiplier
451 ( grep { $aliases_by_type->{multiplying}{$_} } @{ $j->{-join_path}||[] } )
455 # get a column to source/alias map (including unambiguous unqualified ones)
456 my $colinfo = $self->_resolve_column_info ($from);
458 # set up a botched SQLA
459 my $sql_maker = $self->sql_maker;
461 # these are throw away results, do not pollute the bind stack
462 local $sql_maker->{select_bind};
463 local $sql_maker->{where_bind};
464 local $sql_maker->{group_bind};
465 local $sql_maker->{having_bind};
466 local $sql_maker->{from_bind};
468 # we can't scan properly without any quoting (\b doesn't cut it
469 # everywhere), so unless there is proper quoting set - use our
470 # own weird impossible character.
471 # Also in the case of no quoting, we need to explicitly disable
472 # name_sep, otherwise sorry nasty legacy syntax like
473 # { 'count(foo.id)' => { '>' => 3 } } will stop working >:(
474 local $sql_maker->{quote_char} = $sql_maker->{quote_char};
475 local $sql_maker->{name_sep} = $sql_maker->{name_sep};
477 unless (defined $sql_maker->{quote_char} and length $sql_maker->{quote_char}) {
478 $sql_maker->{quote_char} = ["\x00", "\xFF"];
479 # if we don't unset it we screw up retarded but unfortunately working
480 # 'MAX(foo.bar)' => { '>', 3 }
481 $sql_maker->{name_sep} = '';
484 # local is not enough - need to ensure the inner objects get rebuilt
485 $sql_maker->clear_renderer;
486 $sql_maker->clear_converter;
488 my ($lquote, $rquote, $sep) = map { quotemeta $_ } ($sql_maker->_quote_chars, $sql_maker->name_sep);
490 # generate sql chunks
494 ? ($sql_maker->_recurse_where($where))[0]
498 ? ($sql_maker->_recurse_where($attrs->{having}))[0]
504 ? ($sql_maker->_render_sqla(group_by => $attrs->{group_by}))[0]
509 $sql_maker->_recurse_from (
510 ref $from->[0] eq 'ARRAY' ? $from->[0][0] : $from->[0],
511 @{$from}[1 .. $#$from],
516 ? ($sql_maker->_render_sqla(select_select => $select))[0]
520 map { $_->[0] } $self->_extract_order_criteria ($attrs->{order_by}, $sql_maker),
524 # local is not enough - need to ensure the inner objects get rebuilt
525 $sql_maker->clear_renderer;
526 $sql_maker->clear_converter;
528 # throw away empty chunks
529 $_ = [ map { $_ || () } @$_ ] for values %$to_scan;
531 # first see if we have any exact matches (qualified or unqualified)
532 for my $type (keys %$to_scan) {
533 for my $piece (@{$to_scan->{$type}}) {
534 if ($colinfo->{$piece} and my $alias = $colinfo->{$piece}{-source_alias}) {
535 $aliases_by_type->{$type}{$alias} ||= { -parents => $alias_list->{$alias}{-join_path}||[] };
536 $aliases_by_type->{$type}{$alias}{-seen_columns}{$colinfo->{$piece}{-fq_colname}} = $piece;
541 # now loop through all fully qualified columns and get the corresponding
542 # alias (should work even if they are in scalarrefs)
543 for my $alias (keys %$alias_list) {
545 $lquote $alias $rquote $sep (?: $lquote ([^$rquote]+) $rquote )?
547 \b $alias \. ([^\s\)\($rquote]+)?
550 for my $type (keys %$to_scan) {
551 for my $piece (@{$to_scan->{$type}}) {
552 if (my @matches = $piece =~ /$al_re/g) {
553 $aliases_by_type->{$type}{$alias} ||= { -parents => $alias_list->{$alias}{-join_path}||[] };
554 $aliases_by_type->{$type}{$alias}{-seen_columns}{"$alias.$_"} = "$alias.$_"
555 for grep { defined $_ } @matches;
561 # now loop through unqualified column names, and try to locate them within
563 for my $col (keys %$colinfo) {
564 next if $col =~ / \. /x; # if column is qualified it was caught by the above
566 my $col_re = qr/ $lquote ($col) $rquote /x;
568 for my $type (keys %$to_scan) {
569 for my $piece (@{$to_scan->{$type}}) {
570 if ( my @matches = $piece =~ /$col_re/g) {
571 my $alias = $colinfo->{$col}{-source_alias};
572 $aliases_by_type->{$type}{$alias} ||= { -parents => $alias_list->{$alias}{-join_path}||[] };
573 $aliases_by_type->{$type}{$alias}{-seen_columns}{"$alias.$_"} = $_
574 for grep { defined $_ } @matches;
580 # Add any non-left joins to the restriction list (such joins are indeed restrictions)
581 for my $j (values %$alias_list) {
582 my $alias = $j->{-alias} or next;
583 $aliases_by_type->{restricting}{$alias} ||= { -parents => $j->{-join_path}||[] } if (
584 (not $j->{-join_type})
586 ($j->{-join_type} !~ /^left (?: \s+ outer)? $/xi)
590 for (keys %$aliases_by_type) {
591 delete $aliases_by_type->{$_} unless keys %{$aliases_by_type->{$_}};
594 return $aliases_by_type;
597 # This is the engine behind { distinct => 1 }
598 sub _group_over_selection {
599 my ($self, $attrs) = @_;
601 my $colinfos = $self->_resolve_column_info ($attrs->{from});
603 my (@group_by, %group_index);
605 # the logic is: if it is a { func => val } we assume an aggregate,
606 # otherwise if \'...' or \[...] we assume the user knows what is
607 # going on thus group over it
608 for (@{$attrs->{select}}) {
609 if (! ref($_) or ref ($_) ne 'HASH' ) {
612 if ($colinfos->{$_} and $_ !~ /\./ ) {
613 # add a fully qualified version as well
614 $group_index{"$colinfos->{$_}{-source_alias}.$_"}++;
619 # add any order_by parts *from the main source* that are not already
620 # present in the group_by
621 # we need to be careful not to add any named functions/aggregates
622 # i.e. order_by => [ ... { count => 'foo' } ... ]
624 for ($self->_extract_order_criteria($attrs->{order_by})) {
625 # only consider real columns (for functions the user got to do an explicit group_by)
635 $colinfos->{$chunk}{-source_alias} ne $attrs->{alias}
641 $chunk = $colinfos->{$chunk}{-fq_colname};
642 push @group_by, $chunk unless $group_index{$chunk}++;
646 ? (\@group_by, (@leftovers ? \@leftovers : undef) )
651 sub _resolve_ident_sources {
652 my ($self, $ident) = @_;
654 my $alias2source = {};
656 # the reason this is so contrived is that $ident may be a {from}
657 # structure, specifying multiple tables to join
658 if ( blessed $ident && $ident->isa("DBIx::Class::ResultSource") ) {
659 # this is compat mode for insert/update/delete which do not deal with aliases
660 $alias2source->{me} = $ident;
662 elsif (ref $ident eq 'ARRAY') {
666 if (ref $_ eq 'HASH') {
669 if (ref $_ eq 'ARRAY' and ref $_->[0] eq 'HASH') {
673 $alias2source->{$tabinfo->{-alias}} = $tabinfo->{-rsrc}
674 if ($tabinfo->{-rsrc});
678 return $alias2source;
681 # Takes $ident, \@column_names
683 # returns { $column_name => \%column_info, ... }
684 # also note: this adds -result_source => $rsrc to the column info
686 # If no columns_names are supplied returns info about *all* columns
688 sub _resolve_column_info {
689 my ($self, $ident, $colnames) = @_;
690 my $alias2src = $self->_resolve_ident_sources($ident);
692 my (%seen_cols, @auto_colnames);
694 # compile a global list of column names, to be able to properly
695 # disambiguate unqualified column names (if at all possible)
696 for my $alias (keys %$alias2src) {
697 my $rsrc = $alias2src->{$alias};
698 for my $colname ($rsrc->columns) {
699 push @{$seen_cols{$colname}}, $alias;
700 push @auto_colnames, "$alias.$colname" unless $colnames;
706 grep { @{$seen_cols{$_}} == 1 } (keys %seen_cols),
709 my (%return, $colinfos);
710 foreach my $col (@$colnames) {
711 my ($source_alias, $colname) = $col =~ m/^ (?: ([^\.]+) \. )? (.+) $/x;
713 # if the column was seen exactly once - we know which rsrc it came from
714 $source_alias ||= $seen_cols{$colname}[0]
715 if ($seen_cols{$colname} and @{$seen_cols{$colname}} == 1);
717 next unless $source_alias;
719 my $rsrc = $alias2src->{$source_alias}
724 ( $colinfos->{$source_alias} ||= $rsrc->columns_info )->{$colname}
726 $self->throw_exception(
727 "No such column '$colname' on source " . $rsrc->source_name
730 -result_source => $rsrc,
731 -source_alias => $source_alias,
732 -fq_colname => $col eq $colname ? "$source_alias.$col" : $col,
733 -colname => $colname,
736 $return{"$source_alias.$colname"} = $return{$col} if $col eq $colname;
742 # The DBIC relationship chaining implementation is pretty simple - every
743 # new related_relationship is pushed onto the {from} stack, and the {select}
744 # window simply slides further in. This means that when we count somewhere
745 # in the middle, we got to make sure that everything in the join chain is an
746 # actual inner join, otherwise the count will come back with unpredictable
747 # results (a resultset may be generated with _some_ rows regardless of if
748 # the relation which the $rs currently selects has rows or not). E.g.
749 # $artist_rs->cds->count - normally generates:
750 # SELECT COUNT( * ) FROM artist me LEFT JOIN cd cds ON cds.artist = me.artistid
751 # which actually returns the number of artists * (number of cds || 1)
753 # So what we do here is crawl {from}, determine if the current alias is at
754 # the top of the stack, and if not - make sure the chain is inner-joined down
757 sub _inner_join_to_node {
758 my ($self, $from, $alias) = @_;
760 # subqueries and other oddness are naturally not supported
766 ref $from->[0] ne 'HASH'
770 $from->[0]{-alias} eq $alias # this last bit means $alias is the head of $from - nothing to do
773 # find the current $alias in the $from structure
776 for my $j (@{$from}[1 .. $#$from]) {
777 if ($j->[0]{-alias} eq $alias) {
778 $switch_branch = $j->[0]{-join_path};
783 # something else went quite wrong
784 return $from unless $switch_branch;
786 # So it looks like we will have to switch some stuff around.
787 # local() is useless here as we will be leaving the scope
788 # anyway, and deep cloning is just too fucking expensive
789 # So replace the first hashref in the node arrayref manually
790 my @new_from = ($from->[0]);
791 my $sw_idx = { map { (values %$_), 1 } @$switch_branch }; #there's one k/v per join-path
793 for my $j (@{$from}[1 .. $#$from]) {
794 my $jalias = $j->[0]{-alias};
796 if ($sw_idx->{$jalias}) {
797 my %attrs = %{$j->[0]};
798 delete $attrs{-join_type};
812 sub _extract_order_criteria {
813 my ($self, $order_by, $sql_maker) = @_;
815 $sql_maker ||= $self->sql_maker;
817 my $order_dq = $sql_maker->converter->_order_by_to_dq($order_by);
820 while (is_Order($order_dq)) {
821 push @by, $order_dq->{by};
822 $order_dq = $order_dq->{from};
825 delete local @{$sql_maker}{qw(quote_char renderer converter)};
827 return map { [ $sql_maker->_render_dq($_) ] } @by;
830 my ($sql_maker, $order_by, $orig_quote_chars) = @_;
832 return scalar $sql_maker->_order_by_chunks ($order_by)
835 my ($lq, $rq, $sep) = map { quotemeta($_) } (
836 ($orig_quote_chars ? @$orig_quote_chars : $sql_maker->_quote_chars),
841 for ($sql_maker->_order_by_chunks ($order_by) ) {
842 my $chunk = ref $_ ? [ @$_ ] : [ $_ ];
843 ($chunk->[0]) = $sql_maker->_split_order_chunk($chunk->[0]);
845 # order criteria may have come back pre-quoted (literals and whatnot)
846 # this is fragile, but the best we can currently do
847 $chunk->[0] =~ s/^ $lq (.+?) $rq $sep $lq (.+?) $rq $/"$1.$2"/xe
848 or $chunk->[0] =~ s/^ $lq (.+) $rq $/$1/x;
850 push @chunks, $chunk;
857 return $parser->($sql_maker, $order_by);
860 $sql_maker = $self->sql_maker;
862 # pass these in to deal with literals coming from
863 # the user or the deep guts of prefetch
864 my $orig_quote_chars = [$sql_maker->_quote_chars];
866 local $sql_maker->{quote_char};
867 return $parser->($sql_maker, $order_by, $orig_quote_chars);
871 sub _order_by_is_stable {
872 my ($self, $ident, $order_by, $where) = @_;
874 my $colinfo = $self->_resolve_column_info($ident, [
875 (map { $_->[0] } $self->_extract_order_criteria($order_by)),
876 $where ? @{$self->_extract_fixed_condition_columns($where)} :(),
879 return undef unless keys %$colinfo;
882 $cols_per_src->{$_->{-source_alias}}{$_->{-colname}} = $_ for values %$colinfo;
884 for (values %$cols_per_src) {
885 my $src = (values %$_)[0]->{-result_source};
886 return 1 if $src->_identifying_column_set($_);
892 # this is almost identical to the above, except it accepts only
893 # a single rsrc, and will succeed only if the first portion of the order
895 # returns that portion as a colinfo hashref on success
896 sub _main_source_order_by_portion_is_stable {
897 my ($self, $main_rsrc, $order_by, $where) = @_;
899 die "Huh... I expect a blessed result_source..."
900 if ref($main_rsrc) eq 'ARRAY';
904 ( $self->_extract_order_criteria($order_by) )
906 return unless @ord_cols;
908 my $colinfos = $self->_resolve_column_info($main_rsrc);
910 for (0 .. $#ord_cols) {
912 ! $colinfos->{$ord_cols[$_]}
914 $colinfos->{$ord_cols[$_]}{-result_source} != $main_rsrc
921 # we just truncated it above
922 return unless @ord_cols;
924 my $order_portion_ci = { map {
925 $colinfos->{$_}{-colname} => $colinfos->{$_},
926 $colinfos->{$_}{-fq_colname} => $colinfos->{$_},
929 # since all we check here are the start of the order_by belonging to the
930 # top level $rsrc, a present identifying set will mean that the resultset
931 # is ordered by its leftmost table in a stable manner
933 # RV of _identifying_column_set contains unqualified names only
934 my $unqualified_idset = $main_rsrc->_identifying_column_set({
936 $self->_resolve_column_info(
937 $main_rsrc, $self->_extract_fixed_condition_columns($where)
944 my %unqualified_idcols_from_order = map {
945 $order_portion_ci->{$_} ? ( $_ => $order_portion_ci->{$_} ) : ()
946 } @$unqualified_idset;
948 # extra optimization - cut the order_by at the end of the identifying set
949 # (just in case the user was stupid and overlooked the obvious)
950 for my $i (0 .. $#ord_cols) {
951 my $col = $ord_cols[$i];
952 my $unqualified_colname = $order_portion_ci->{$col}{-colname};
953 $ret_info->{$col} = { %{$order_portion_ci->{$col}}, -idx_in_order_subset => $i };
954 delete $unqualified_idcols_from_order{$ret_info->{$col}{-colname}};
956 # we didn't reach the end of the identifying portion yet
957 return $ret_info unless keys %unqualified_idcols_from_order;
960 die 'How did we get here...';
963 # returns an arrayref of column names which *definitely* have some
964 # sort of non-nullable equality requested in the given condition
965 # specification. This is used to figure out if a resultset is
966 # constrained to a column which is part of a unique constraint,
967 # which in turn allows us to better predict how ordering will behave
970 # this is a rudimentary, incomplete, and error-prone extractor
971 # however this is OK - it is conservative, and if we can not find
972 # something that is in fact there - the stack will recover gracefully
973 # Also - DQ and the mst it rode in on will save us all RSN!!!
974 sub _extract_fixed_condition_columns {
975 my ($self, $where, $nested) = @_;
977 return unless ref $where eq 'HASH';
980 for my $lhs (keys %$where) {
981 if ($lhs =~ /^\-and$/i) {
982 push @cols, ref $where->{$lhs} eq 'ARRAY'
983 ? ( map { $self->_extract_fixed_condition_columns($_, 1) } @{$where->{$lhs}} )
984 : $self->_extract_fixed_condition_columns($where->{$lhs}, 1)
987 elsif ($lhs !~ /^\-/) {
988 my $val = $where->{$lhs};
990 push @cols, $lhs if (defined $val and (
993 (ref $val eq 'HASH' and keys %$val == 1 and defined $val->{'='})
997 return $nested ? @cols : \@cols;