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';
22 # This code will remove non-selecting/non-restricting joins from
23 # {from} specs, aiding the RDBMS query optimizer
25 sub _prune_unused_joins {
27 my ($from, $select, $where, $attrs, $ignore_multiplication) = @_;
29 return $from unless $self->_use_join_optimizer;
31 if (ref $from ne 'ARRAY' || ref $from->[0] ne 'HASH' || ref $from->[1] ne 'ARRAY') {
32 return $from; # only standard {from} specs are supported
35 my $aliastypes = $self->_resolve_aliastypes_from_select_args(@_);
38 delete $aliastypes->{joining};
40 # a grouped set will not be affected by amount of rows. Thus any
41 # {multiplying} joins can go
42 delete $aliastypes->{multiplying}
43 if $ignore_multiplication or $attrs->{group_by};
45 my @newfrom = $from->[0]; # FROM head is always present
49 for (values %$aliastypes) {
50 # add all requested aliases
51 $need_joins{$_} = 1 for keys %$_;
53 # add all their parents (as per joinpath which is an AoH { table => alias })
54 $need_joins{$_} = 1 for map { values %$_ } map { @{$_->{-parents}} } values %$_;
57 for my $j (@{$from}[1..$#$from]) {
58 push @newfrom, $j if (
59 (! $j->[0]{-alias}) # legacy crap
61 $need_joins{$j->[0]{-alias}}
69 # This is the code producing joined subqueries like:
70 # SELECT me.*, other.* FROM ( SELECT me.* FROM ... ) JOIN other ON ...
72 sub _adjust_select_args_for_complex_prefetch {
73 my ($self, $from, $select, $where, $attrs) = @_;
75 $self->throw_exception ('Complex prefetches are not supported on resultsets with a custom from attribute')
76 if (ref $from ne 'ARRAY' || ref $from->[0] ne 'HASH' || ref $from->[1] ne 'ARRAY');
78 my $root_alias = $attrs->{alias};
80 # generate inner/outer attribute lists, remove stuff that doesn't apply
81 my $outer_attrs = { %$attrs };
82 delete $outer_attrs->{$_} for qw/where bind rows offset group_by _grouped_by_distinct having/;
84 my $inner_attrs = { %$attrs };
85 delete $inner_attrs->{$_} for qw/from for collapse select as _related_results_construction/;
87 # there is no point of ordering the insides if there is no limit
88 delete $inner_attrs->{order_by} if (
89 delete $inner_attrs->{_order_is_artificial}
91 ! $inner_attrs->{rows}
94 # generate the inner/outer select lists
95 # for inside we consider only stuff *not* brought in by the prefetch
96 # on the outside we substitute any function for its alias
97 my $outer_select = [ @$select ];
100 my ($root_node, $root_node_offset);
102 for my $i (0 .. $#$from) {
103 my $node = $from->[$i];
104 my $h = (ref $node eq 'HASH') ? $node
105 : (ref $node eq 'ARRAY' and ref $node->[0] eq 'HASH') ? $node->[0]
109 if ( ($h->{-alias}||'') eq $root_alias and $h->{-rsrc} ) {
111 $root_node_offset = $i;
116 $self->throw_exception ('Complex prefetches are not supported on resultsets with a custom from attribute')
119 # use the heavy duty resolver to take care of aliased/nonaliased naming
120 my $colinfo = $self->_resolve_column_info($from);
121 my $selected_root_columns;
123 for my $i (0 .. $#$outer_select) {
124 my $sel = $outer_select->[$i];
127 $colinfo->{$sel} and $colinfo->{$sel}{-source_alias} ne $root_alias
130 if (ref $sel eq 'HASH' ) {
131 $sel->{-as} ||= $attrs->{as}[$i];
132 $outer_select->[$i] = join ('.', $root_alias, ($sel->{-as} || "inner_column_$i") );
134 elsif (! ref $sel and my $ci = $colinfo->{$sel}) {
135 $selected_root_columns->{$ci->{-colname}} = 1;
138 push @$inner_select, $sel;
140 push @{$inner_attrs->{as}}, $attrs->{as}[$i];
143 # We will need to fetch all native columns in the inner subquery, which may
144 # be a part of an *outer* join condition, or an order_by (which needs to be
146 # We can not just fetch everything because a potential has_many restricting
147 # join collapse *will not work* on heavy data types.
148 my $connecting_aliastypes = $self->_resolve_aliastypes_from_select_args(
149 [grep { ref($_) eq 'ARRAY' or ref($_) eq 'HASH' } @{$from}[$root_node_offset .. $#$from]],
155 for (sort map { keys %{$_->{-seen_columns}||{}} } map { values %$_ } values %$connecting_aliastypes) {
156 my $ci = $colinfo->{$_} or next;
158 $ci->{-source_alias} eq $root_alias
160 ! $selected_root_columns->{$ci->{-colname}}++
162 # adding it to both to keep limits not supporting dark selectors happy
163 push @$inner_select, $ci->{-fq_colname};
164 push @{$inner_attrs->{as}}, $ci->{-fq_colname};
168 # construct the inner $from and lock it in a subquery
169 # we need to prune first, because this will determine if we need a group_by below
170 # throw away all non-selecting, non-restricting multijoins
171 # (since we def. do not care about multiplication those inside the subquery)
172 my $inner_subq = do {
174 # must use it here regardless of user requests
175 local $self->{_use_join_optimizer} = 1;
177 # throw away multijoins since we def. do not care about those inside the subquery
178 my $inner_from = $self->_prune_unused_joins ($from, $inner_select, $where, $inner_attrs, 'ignore_multiplication');
180 my $inner_aliastypes =
181 $self->_resolve_aliastypes_from_select_args( $inner_from, $inner_select, $where, $inner_attrs );
183 # uh-oh a multiplier (which is not us) left in, this is a problem
185 $inner_aliastypes->{multiplying}
187 !$inner_aliastypes->{grouping} # if there are groups - assume user knows wtf they are up to
189 my @multipliers = grep { $_ ne $root_alias } keys %{$inner_aliastypes->{multiplying}}
192 # if none of the multipliers came from an order_by (guaranteed to have been combined
193 # with a limit) - easy - just slap a group_by to simulate a collape and be on our way
195 ! $inner_aliastypes->{ordering}
197 ! first { $inner_aliastypes->{ordering}{$_} } @multipliers
199 my $unprocessed_order_chunks;
200 ($inner_attrs->{group_by}, $unprocessed_order_chunks) = $self->_group_over_selection (
201 $inner_from, $inner_select, $inner_attrs->{order_by}
204 $self->throw_exception (
205 'A required group_by clause could not be constructed automatically due to a complex '
206 . 'order_by criteria. Either order_by columns only (no functions) or construct a suitable '
208 ) if $unprocessed_order_chunks;
211 # We need to order by external columns and group at the same time
212 # so we can calculate the proper limit
213 # This doesn't really make sense in SQL, however from DBICs point
214 # of view is rather valid (order the leftmost objects by whatever
215 # criteria and get the offset/rows many). There is a way around
216 # this however in SQL - we simply tae the direction of each piece
217 # of the foreign order and convert them to MIN(X) for ASC or MAX(X)
218 # for DESC, and group_by the root columns. The end result should be
219 # exactly what we expect
221 # FIXME REMOVE LATER - (just a sanity check)
222 if (defined ( my $impostor = first
223 { $_ ne $root_alias }
224 keys %{ $inner_aliastypes->{selecting} }
226 $self->throw_exception(sprintf
227 'Unexpected inner selection during complex prefetch (%s)...',
228 join ', ', keys %{ $inner_aliastypes->{joining}{$impostor}{-seen_columns} || {} }
232 # supplement the main selection with pks if not already there,
233 # as they will have to be a part of the group_by to colapse
235 my $cur_sel = { map { $_ => 1 } @$inner_select };
236 my @pks = map { "$root_alias.$_" } $root_node->{-rsrc}->primary_columns
237 or $self->throw_exception( sprintf
238 'Unable to perform complex limited prefetch off %s without declared primary key',
239 $root_node->{-rsrc}->source_name,
242 push @$inner_select, $col
243 unless $cur_sel->{$col}++;
246 # wrap any part of the order_by that "responds" to an ordering alias
248 # FIXME - this code is a joke, will need to be completely rewritten in
249 # the DQ branch. But I need to push a POC here, otherwise the
250 # pesky tests won't pass
251 my $sql_maker = $self->sql_maker;
252 my ($lquote, $rquote, $sep) = map { quotemeta $_ } ($sql_maker->_quote_chars, $sql_maker->name_sep);
253 my $own_re = qr/ $lquote \Q$root_alias\E $rquote $sep | \b \Q$root_alias\E $sep /x;
254 my @order_chunks = map { ref $_ eq 'ARRAY' ? $_ : [ $_ ] } $sql_maker->_order_by_chunks($attrs->{order_by});
255 my @new_order = map { \$_ } @order_chunks;
256 my $inner_columns_info = $self->_resolve_column_info($inner_from);
258 # loop through and replace stuff that is not "ours" with a min/max func
259 # everything is a literal at this point, since we are likely properly
261 for my $i (0 .. $#new_order) {
262 my $chunk = $order_chunks[$i][0];
265 next if $chunk =~ $own_re;
267 my $is_desc = $chunk =~ s/\sDESC$//i;
268 $chunk =~ s/\sASC$//i;
270 # maybe our own unqualified column
271 my ($ord_bit) = ($lquote and $sep)
272 ? $chunk =~ /^ $lquote ([^$sep]+) $rquote $/x
278 $inner_columns_info->{$ord_bit}
280 $inner_columns_info->{$ord_bit}{-source_alias} eq $root_alias
286 ($is_desc ? 'MAX' : 'MIN'),
288 ($is_desc ? ' DESC' : ''),
290 @ {$order_chunks[$i]} [ 1 .. $#{$order_chunks[$i]} ]
294 $inner_attrs->{order_by} = \@new_order;
296 # do not care about leftovers here - it will be all the functions
298 ($inner_attrs->{group_by}) = $self->_group_over_selection (
299 $inner_from, $inner_select, $inner_attrs->{order_by}
304 # we already optimized $inner_from above
305 # and already local()ized
306 $self->{_use_join_optimizer} = 0;
308 # generate the subquery
309 $self->_select_args_to_query (
317 # Generate the outer from - this is relatively easy (really just replace
318 # the join slot with the subquery), with a major caveat - we can not
319 # join anything that is non-selecting (not part of the prefetch), but at
320 # the same time is a multi-type relationship, as it will explode the result.
322 # There are two possibilities here
323 # - either the join is non-restricting, in which case we simply throw it away
324 # - it is part of the restrictions, in which case we need to collapse the outer
325 # result by tackling yet another group_by to the outside of the query
327 # work on a shallow copy
332 # we may not be the head
333 if ($root_node_offset) {
334 # first generate the outer_from, up to the substitution point
335 @outer_from = splice @$from, 0, $root_node_offset;
339 -alias => $root_alias,
340 -rsrc => $root_node->{-rsrc},
341 $root_alias => $inner_subq,
343 @{$from->[0]}[1 .. $#{$from->[0]}],
348 -alias => $root_alias,
349 -rsrc => $root_node->{-rsrc},
350 $root_alias => $inner_subq,
354 shift @$from; # it's replaced in @outer_from already
356 # scan the *remaining* from spec against different attributes, and see which joins are needed
358 my $outer_aliastypes =
359 $self->_resolve_aliastypes_from_select_args( $from, $outer_select, $where, $outer_attrs );
362 my ($outer_select_chain, @outer_nonselecting_chains) = map { +{
363 map { $_ => 1 } map { values %$_} map { @{$_->{-parents}} } values %{ $outer_aliastypes->{$_} || {} }
364 } } qw/selecting restricting grouping ordering/;
366 # see what's left - throw away if not selecting/restricting
367 # also throw in a group_by if a non-selecting multiplier,
368 # to guard against cross-join explosions
369 my $need_outer_group_by;
370 while (my $j = shift @$from) {
371 my $alias = $j->[0]{-alias};
374 $outer_select_chain->{$alias}
378 elsif (first { $_->{$alias} } @outer_nonselecting_chains ) {
379 push @outer_from, $j;
380 $need_outer_group_by ||= $outer_aliastypes->{multiplying}{$alias} ? 1 : 0;
384 if ( $need_outer_group_by and $attrs->{_grouped_by_distinct} ) {
386 my $unprocessed_order_chunks;
387 ($outer_attrs->{group_by}, $unprocessed_order_chunks) = $self->_group_over_selection (
388 \@outer_from, $outer_select, $outer_attrs->{order_by}
391 $self->throw_exception (
392 'A required group_by clause could not be constructed automatically due to a complex '
393 . 'order_by criteria. Either order_by columns only (no functions) or construct a suitable '
395 ) if $unprocessed_order_chunks;
399 # This is totally horrific - the $where ends up in both the inner and outer query
400 # Unfortunately not much can be done until SQLA2 introspection arrives, and even
401 # then if where conditions apply to the *right* side of the prefetch, you may have
402 # to both filter the inner select (e.g. to apply a limit) and then have to re-filter
403 # the outer select to exclude joins you didin't want in the first place
405 # OTOH it can be seen as a plus: <ash> (notes that this query would make a DBA cry ;)
406 return (\@outer_from, $outer_select, $where, $outer_attrs);
410 # I KNOW THIS SUCKS! GET SQLA2 OUT THE DOOR SO THIS CAN DIE!
412 # Due to a lack of SQLA2 we fall back to crude scans of all the
413 # select/where/order/group attributes, in order to determine what
414 # aliases are neded to fulfill the query. This information is used
415 # throughout the code to prune unnecessary JOINs from the queries
416 # in an attempt to reduce the execution time.
417 # Although the method is pretty horrific, the worst thing that can
418 # happen is for it to fail due to some scalar SQL, which in turn will
419 # result in a vocal exception.
420 sub _resolve_aliastypes_from_select_args {
421 my ( $self, $from, $select, $where, $attrs ) = @_;
423 $self->throw_exception ('Unable to analyze custom {from}')
424 if ref $from ne 'ARRAY';
426 # what we will return
429 # see what aliases are there to work with
433 $j = $j->[0] if ref $j eq 'ARRAY';
434 my $al = $j->{-alias}
437 $alias_list->{$al} = $j;
438 $aliases_by_type->{multiplying}{$al} ||= { -parents => $j->{-join_path}||[] } if (
439 # not array == {from} head == can't be multiplying
440 ( ref($_) eq 'ARRAY' and ! $j->{-is_single} )
442 # a parent of ours is already a multiplier
443 ( grep { $aliases_by_type->{multiplying}{$_} } @{ $j->{-join_path}||[] } )
447 # get a column to source/alias map (including unqualified ones)
448 my $colinfo = $self->_resolve_column_info ($from);
450 # set up a botched SQLA
451 my $sql_maker = $self->sql_maker;
453 # these are throw away results, do not pollute the bind stack
454 local $sql_maker->{select_bind};
455 local $sql_maker->{where_bind};
456 local $sql_maker->{group_bind};
457 local $sql_maker->{having_bind};
458 local $sql_maker->{from_bind};
460 # we can't scan properly without any quoting (\b doesn't cut it
461 # everywhere), so unless there is proper quoting set - use our
462 # own weird impossible character.
463 # Also in the case of no quoting, we need to explicitly disable
464 # name_sep, otherwise sorry nasty legacy syntax like
465 # { 'count(foo.id)' => { '>' => 3 } } will stop working >:(
466 local $sql_maker->{quote_char} = $sql_maker->{quote_char};
467 local $sql_maker->{name_sep} = $sql_maker->{name_sep};
469 unless (defined $sql_maker->{quote_char} and length $sql_maker->{quote_char}) {
470 $sql_maker->{quote_char} = ["\x00", "\xFF"];
471 # if we don't unset it we screw up retarded but unfortunately working
472 # 'MAX(foo.bar)' => { '>', 3 }
473 $sql_maker->{name_sep} = '';
476 my ($lquote, $rquote, $sep) = map { quotemeta $_ } ($sql_maker->_quote_chars, $sql_maker->name_sep);
478 # generate sql chunks
481 $sql_maker->_recurse_where ($where),
482 $sql_maker->_parse_rs_attrs ({ having => $attrs->{having} }),
485 $sql_maker->_parse_rs_attrs ({ group_by => $attrs->{group_by} }),
488 $sql_maker->_recurse_from (
489 ref $from->[0] eq 'ARRAY' ? $from->[0][0] : $from->[0],
490 @{$from}[1 .. $#$from],
494 $sql_maker->_recurse_fields ($select),
497 map { $_->[0] } $self->_extract_order_criteria ($attrs->{order_by}, $sql_maker),
501 # throw away empty chunks
502 $_ = [ map { $_ || () } @$_ ] for values %$to_scan;
504 # first loop through all fully qualified columns and get the corresponding
505 # alias (should work even if they are in scalarrefs)
506 for my $alias (keys %$alias_list) {
508 $lquote $alias $rquote $sep (?: $lquote ([^$rquote]+) $rquote )?
510 \b $alias \. ([^\s\)\($rquote]+)?
513 for my $type (keys %$to_scan) {
514 for my $piece (@{$to_scan->{$type}}) {
515 if (my @matches = $piece =~ /$al_re/g) {
516 $aliases_by_type->{$type}{$alias} ||= { -parents => $alias_list->{$alias}{-join_path}||[] };
517 $aliases_by_type->{$type}{$alias}{-seen_columns}{"$alias.$_"} = "$alias.$_"
518 for grep { defined $_ } @matches;
524 # now loop through unqualified column names, and try to locate them within
526 for my $col (keys %$colinfo) {
527 next if $col =~ / \. /x; # if column is qualified it was caught by the above
529 my $col_re = qr/ $lquote ($col) $rquote /x;
531 for my $type (keys %$to_scan) {
532 for my $piece (@{$to_scan->{$type}}) {
533 if (my @matches = $piece =~ /$col_re/g) {
534 my $alias = $colinfo->{$col}{-source_alias};
535 $aliases_by_type->{$type}{$alias} ||= { -parents => $alias_list->{$alias}{-join_path}||[] };
536 $aliases_by_type->{$type}{$alias}{-seen_columns}{"$alias.$_"} = $_
537 for grep { defined $_ } @matches;
543 # Add any non-left joins to the restriction list (such joins are indeed restrictions)
544 for my $j (values %$alias_list) {
545 my $alias = $j->{-alias} or next;
546 $aliases_by_type->{restricting}{$alias} ||= { -parents => $j->{-join_path}||[] } if (
547 (not $j->{-join_type})
549 ($j->{-join_type} !~ /^left (?: \s+ outer)? $/xi)
553 for (keys %$aliases_by_type) {
554 delete $aliases_by_type->{$_} unless keys %{$aliases_by_type->{$_}};
557 return $aliases_by_type;
560 # This is the engine behind { distinct => 1 }
561 sub _group_over_selection {
562 my ($self, $from, $select, $order_by) = @_;
564 my $rs_column_list = $self->_resolve_column_info ($from);
566 my (@group_by, %group_index);
568 # the logic is: if it is a { func => val } we assume an aggregate,
569 # otherwise if \'...' or \[...] we assume the user knows what is
570 # going on thus group over it
572 if (! ref($_) or ref ($_) ne 'HASH' ) {
575 if ($rs_column_list->{$_} and $_ !~ /\./ ) {
576 # add a fully qualified version as well
577 $group_index{"$rs_column_list->{$_}{-source_alias}.$_"}++;
582 # add any order_by parts that are not already present in the group_by
583 # we need to be careful not to add any named functions/aggregates
584 # i.e. order_by => [ ... { count => 'foo' } ... ]
586 for ($self->_extract_order_criteria($order_by)) {
587 # only consider real columns (for functions the user got to do an explicit group_by)
593 my $colinfo = $rs_column_list->{$chunk} or do {
598 $chunk = "$colinfo->{-source_alias}.$chunk" if $chunk !~ /\./;
599 push @group_by, $chunk unless $group_index{$chunk}++;
603 ? (\@group_by, (@leftovers ? \@leftovers : undef) )
608 sub _resolve_ident_sources {
609 my ($self, $ident) = @_;
611 my $alias2source = {};
614 # the reason this is so contrived is that $ident may be a {from}
615 # structure, specifying multiple tables to join
616 if ( blessed $ident && $ident->isa("DBIx::Class::ResultSource") ) {
617 # this is compat mode for insert/update/delete which do not deal with aliases
618 $alias2source->{me} = $ident;
621 elsif (ref $ident eq 'ARRAY') {
625 if (ref $_ eq 'HASH') {
627 $rs_alias = $tabinfo->{-alias};
629 if (ref $_ eq 'ARRAY' and ref $_->[0] eq 'HASH') {
633 $alias2source->{$tabinfo->{-alias}} = $tabinfo->{-rsrc}
634 if ($tabinfo->{-rsrc});
638 return ($alias2source, $rs_alias);
641 # Takes $ident, \@column_names
643 # returns { $column_name => \%column_info, ... }
644 # also note: this adds -result_source => $rsrc to the column info
646 # If no columns_names are supplied returns info about *all* columns
648 sub _resolve_column_info {
649 my ($self, $ident, $colnames) = @_;
650 my ($alias2src, $root_alias) = $self->_resolve_ident_sources($ident);
652 my (%seen_cols, @auto_colnames);
654 # compile a global list of column names, to be able to properly
655 # disambiguate unqualified column names (if at all possible)
656 for my $alias (keys %$alias2src) {
657 my $rsrc = $alias2src->{$alias};
658 for my $colname ($rsrc->columns) {
659 push @{$seen_cols{$colname}}, $alias;
660 push @auto_colnames, "$alias.$colname" unless $colnames;
666 grep { @{$seen_cols{$_}} == 1 } (keys %seen_cols),
669 my (%return, $colinfos);
670 foreach my $col (@$colnames) {
671 my ($source_alias, $colname) = $col =~ m/^ (?: ([^\.]+) \. )? (.+) $/x;
673 # if the column was seen exactly once - we know which rsrc it came from
674 $source_alias ||= $seen_cols{$colname}[0]
675 if ($seen_cols{$colname} and @{$seen_cols{$colname}} == 1);
677 next unless $source_alias;
679 my $rsrc = $alias2src->{$source_alias}
684 ( $colinfos->{$source_alias} ||= $rsrc->columns_info )->{$colname}
686 $self->throw_exception(
687 "No such column '$colname' on source " . $rsrc->source_name
690 -result_source => $rsrc,
691 -source_alias => $source_alias,
692 -fq_colname => $col eq $colname ? "$source_alias.$col" : $col,
693 -colname => $colname,
696 $return{"$source_alias.$colname"} = $return{$col} if $col eq $colname;
702 # The DBIC relationship chaining implementation is pretty simple - every
703 # new related_relationship is pushed onto the {from} stack, and the {select}
704 # window simply slides further in. This means that when we count somewhere
705 # in the middle, we got to make sure that everything in the join chain is an
706 # actual inner join, otherwise the count will come back with unpredictable
707 # results (a resultset may be generated with _some_ rows regardless of if
708 # the relation which the $rs currently selects has rows or not). E.g.
709 # $artist_rs->cds->count - normally generates:
710 # SELECT COUNT( * ) FROM artist me LEFT JOIN cd cds ON cds.artist = me.artistid
711 # which actually returns the number of artists * (number of cds || 1)
713 # So what we do here is crawl {from}, determine if the current alias is at
714 # the top of the stack, and if not - make sure the chain is inner-joined down
717 sub _inner_join_to_node {
718 my ($self, $from, $alias) = @_;
720 # subqueries and other oddness are naturally not supported
726 ref $from->[0] ne 'HASH'
730 $from->[0]{-alias} eq $alias # this last bit means $alias is the head of $from - nothing to do
733 # find the current $alias in the $from structure
736 for my $j (@{$from}[1 .. $#$from]) {
737 if ($j->[0]{-alias} eq $alias) {
738 $switch_branch = $j->[0]{-join_path};
743 # something else went quite wrong
744 return $from unless $switch_branch;
746 # So it looks like we will have to switch some stuff around.
747 # local() is useless here as we will be leaving the scope
748 # anyway, and deep cloning is just too fucking expensive
749 # So replace the first hashref in the node arrayref manually
750 my @new_from = ($from->[0]);
751 my $sw_idx = { map { (values %$_), 1 } @$switch_branch }; #there's one k/v per join-path
753 for my $j (@{$from}[1 .. $#$from]) {
754 my $jalias = $j->[0]{-alias};
756 if ($sw_idx->{$jalias}) {
757 my %attrs = %{$j->[0]};
758 delete $attrs{-join_type};
772 sub _extract_order_criteria {
773 my ($self, $order_by, $sql_maker) = @_;
776 my ($sql_maker, $order_by, $orig_quote_chars) = @_;
778 return scalar $sql_maker->_order_by_chunks ($order_by)
781 my ($lq, $rq, $sep) = map { quotemeta($_) } (
782 ($orig_quote_chars ? @$orig_quote_chars : $sql_maker->_quote_chars),
787 for ($sql_maker->_order_by_chunks ($order_by) ) {
788 my $chunk = ref $_ ? [ @$_ ] : [ $_ ];
789 $chunk->[0] =~ s/\s+ (?: ASC|DESC ) \s* $//ix;
791 # order criteria may have come back pre-quoted (literals and whatnot)
792 # this is fragile, but the best we can currently do
793 $chunk->[0] =~ s/^ $lq (.+?) $rq $sep $lq (.+?) $rq $/"$1.$2"/xe
794 or $chunk->[0] =~ s/^ $lq (.+) $rq $/$1/x;
796 push @chunks, $chunk;
803 return $parser->($sql_maker, $order_by);
806 $sql_maker = $self->sql_maker;
808 # pass these in to deal with literals coming from
809 # the user or the deep guts of prefetch
810 my $orig_quote_chars = [$sql_maker->_quote_chars];
812 local $sql_maker->{quote_char};
813 return $parser->($sql_maker, $order_by, $orig_quote_chars);
817 sub _order_by_is_stable {
818 my ($self, $ident, $order_by, $where) = @_;
820 my $colinfo = $self->_resolve_column_info($ident, [
821 (map { $_->[0] } $self->_extract_order_criteria($order_by)),
822 $where ? @{$self->_extract_fixed_condition_columns($where)} :(),
825 return undef unless keys %$colinfo;
828 $cols_per_src->{$_->{-source_alias}}{$_->{-colname}} = $_ for values %$colinfo;
830 for (values %$cols_per_src) {
831 my $src = (values %$_)[0]->{-result_source};
832 return 1 if $src->_identifying_column_set($_);
838 # this is almost identical to the above, except it accepts only
839 # a single rsrc, and will succeed only if the first portion of the order
841 # returns that portion as a colinfo hashref on success
842 sub _main_source_order_by_portion_is_stable {
843 my ($self, $main_rsrc, $order_by, $where) = @_;
845 die "Huh... I expect a blessed result_source..."
846 if ref($main_rsrc) eq 'ARRAY';
850 ( $self->_extract_order_criteria($order_by) )
852 return unless @ord_cols;
854 my $colinfos = $self->_resolve_column_info($main_rsrc, \@ord_cols);
855 for (0 .. $#ord_cols) {
857 ! $colinfos->{$ord_cols[$_]}
859 $colinfos->{$ord_cols[$_]}{-result_source} != $main_rsrc
866 # we just truncated it above
867 return unless @ord_cols;
869 # since all we check here are the start of the order_by belonging to the
870 # top level $rsrc, a present identifying set will mean that the resultset
871 # is ordered by its leftmost table in a stable manner
873 # single source - safely use both qualified and unqualified name
874 my $order_portion_ci = { map {
875 $colinfos->{$_}{-colname} => $colinfos->{$_},
876 $colinfos->{$_}{-fq_colname} => $colinfos->{$_},
879 $where = $where ? $self->_resolve_column_info(
880 $main_rsrc, $self->_extract_fixed_condition_columns($where)
884 $main_rsrc->_identifying_column_set({ %$where, %$order_portion_ci })
890 # returns an arrayref of column names which *definitely* have som
891 # sort of non-nullable equality requested in the given condition
892 # specification. This is used to figure out if a resultset is
893 # constrained to a column which is part of a unique constraint,
894 # which in turn allows us to better predict how ordering will behave
897 # this is a rudimentary, incomplete, and error-prone extractor
898 # however this is OK - it is conservative, and if we can not find
899 # something that is in fact there - the stack will recover gracefully
900 # Also - DQ and the mst it rode in on will save us all RSN!!!
901 sub _extract_fixed_condition_columns {
902 my ($self, $where, $nested) = @_;
904 return unless ref $where eq 'HASH';
907 for my $lhs (keys %$where) {
908 if ($lhs =~ /^\-and$/i) {
909 push @cols, ref $where->{$lhs} eq 'ARRAY'
910 ? ( map { $self->_extract_fixed_condition_columns($_, 1) } @{$where->{$lhs}} )
911 : $self->_extract_fixed_condition_columns($where->{$lhs}, 1)
914 elsif ($lhs !~ /^\-/) {
915 my $val = $where->{$lhs};
917 push @cols, $lhs if (defined $val and (
920 (ref $val eq 'HASH' and keys %$val == 1 and defined $val->{'='})
924 return $nested ? @cols : \@cols;