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 $sep /x;
254 my @order = @{$attrs->{order_by}};
255 my @order_chunks = map { ref $_ eq 'ARRAY' ? $_ : [ $_ ] } $sql_maker->_order_by_chunks (\@order);
256 $self->throw_exception ('Order By parsing failed...') if @order != @order_chunks;
257 for my $i (0 .. $#order) {
258 # skip ourselves, and anything that looks like a literal
259 next if $order_chunks[$i][0] =~ $own_re;
260 next if (ref $order[$i] and ref $order[$i] ne 'HASH');
262 my $is_desc = $order_chunks[$i][0] =~ s/\sDESC$//i;
263 $order_chunks[$i][0] =~ s/\sASC$//i;
268 ($is_desc ? 'MAX' : 'MIN'),
269 $order_chunks[$i][0],
270 ($is_desc ? ' DESC' : ''),
272 @ {$order_chunks[$i]} [ 1 .. $#{$order_chunks[$i]} ]
276 $inner_attrs->{order_by} = \@order;
277 ($inner_attrs->{group_by}) = $self->_group_over_selection (
278 $inner_from, $inner_select, $inner_attrs->{order_by}
283 # we already optimized $inner_from above
284 # and already local()ized
285 $self->{_use_join_optimizer} = 0;
287 # generate the subquery
288 $self->_select_args_to_query (
296 # Generate the outer from - this is relatively easy (really just replace
297 # the join slot with the subquery), with a major caveat - we can not
298 # join anything that is non-selecting (not part of the prefetch), but at
299 # the same time is a multi-type relationship, as it will explode the result.
301 # There are two possibilities here
302 # - either the join is non-restricting, in which case we simply throw it away
303 # - it is part of the restrictions, in which case we need to collapse the outer
304 # result by tackling yet another group_by to the outside of the query
306 # work on a shallow copy
311 # we may not be the head
312 if ($root_node_offset) {
313 # first generate the outer_from, up to the substitution point
314 @outer_from = splice @$from, 0, $root_node_offset;
318 -alias => $root_alias,
319 -rsrc => $root_node->{-rsrc},
320 $root_alias => $inner_subq,
322 @{$from->[0]}[1 .. $#{$from->[0]}],
327 -alias => $root_alias,
328 -rsrc => $root_node->{-rsrc},
329 $root_alias => $inner_subq,
333 shift @$from; # it's replaced in @outer_from already
335 # scan the *remaining* from spec against different attributes, and see which joins are needed
337 my $outer_aliastypes =
338 $self->_resolve_aliastypes_from_select_args( $from, $outer_select, $where, $outer_attrs );
341 my ($outer_select_chain, @outer_nonselecting_chains) = map { +{
342 map { $_ => 1 } map { values %$_} map { @{$_->{-parents}} } values %{ $outer_aliastypes->{$_} || {} }
343 } } qw/selecting restricting grouping ordering/;
345 # see what's left - throw away if not selecting/restricting
346 # also throw in a group_by if a non-selecting multiplier,
347 # to guard against cross-join explosions
348 my $need_outer_group_by;
349 while (my $j = shift @$from) {
350 my $alias = $j->[0]{-alias};
353 $outer_select_chain->{$alias}
357 elsif (first { $_->{$alias} } @outer_nonselecting_chains ) {
358 push @outer_from, $j;
359 $need_outer_group_by ||= $outer_aliastypes->{multiplying}{$alias} ? 1 : 0;
363 if ( $need_outer_group_by and $attrs->{_grouped_by_distinct} ) {
365 my $unprocessed_order_chunks;
366 ($outer_attrs->{group_by}, $unprocessed_order_chunks) = $self->_group_over_selection (
367 \@outer_from, $outer_select, $outer_attrs->{order_by}
370 $self->throw_exception (
371 'A required group_by clause could not be constructed automatically due to a complex '
372 . 'order_by criteria. Either order_by columns only (no functions) or construct a suitable '
374 ) if $unprocessed_order_chunks;
378 # This is totally horrific - the $where ends up in both the inner and outer query
379 # Unfortunately not much can be done until SQLA2 introspection arrives, and even
380 # then if where conditions apply to the *right* side of the prefetch, you may have
381 # to both filter the inner select (e.g. to apply a limit) and then have to re-filter
382 # the outer select to exclude joins you didin't want in the first place
384 # OTOH it can be seen as a plus: <ash> (notes that this query would make a DBA cry ;)
385 return (\@outer_from, $outer_select, $where, $outer_attrs);
389 # I KNOW THIS SUCKS! GET SQLA2 OUT THE DOOR SO THIS CAN DIE!
391 # Due to a lack of SQLA2 we fall back to crude scans of all the
392 # select/where/order/group attributes, in order to determine what
393 # aliases are neded to fulfill the query. This information is used
394 # throughout the code to prune unnecessary JOINs from the queries
395 # in an attempt to reduce the execution time.
396 # Although the method is pretty horrific, the worst thing that can
397 # happen is for it to fail due to some scalar SQL, which in turn will
398 # result in a vocal exception.
399 sub _resolve_aliastypes_from_select_args {
400 my ( $self, $from, $select, $where, $attrs ) = @_;
402 $self->throw_exception ('Unable to analyze custom {from}')
403 if ref $from ne 'ARRAY';
405 # what we will return
408 # see what aliases are there to work with
412 $j = $j->[0] if ref $j eq 'ARRAY';
413 my $al = $j->{-alias}
416 $alias_list->{$al} = $j;
417 $aliases_by_type->{multiplying}{$al} ||= { -parents => $j->{-join_path}||[] } if (
418 # not array == {from} head == can't be multiplying
419 ( ref($_) eq 'ARRAY' and ! $j->{-is_single} )
421 # a parent of ours is already a multiplier
422 ( grep { $aliases_by_type->{multiplying}{$_} } @{ $j->{-join_path}||[] } )
426 # get a column to source/alias map (including unqualified ones)
427 my $colinfo = $self->_resolve_column_info ($from);
429 # set up a botched SQLA
430 my $sql_maker = $self->sql_maker;
432 # these are throw away results, do not pollute the bind stack
433 local $sql_maker->{select_bind};
434 local $sql_maker->{where_bind};
435 local $sql_maker->{group_bind};
436 local $sql_maker->{having_bind};
437 local $sql_maker->{from_bind};
439 # we can't scan properly without any quoting (\b doesn't cut it
440 # everywhere), so unless there is proper quoting set - use our
441 # own weird impossible character.
442 # Also in the case of no quoting, we need to explicitly disable
443 # name_sep, otherwise sorry nasty legacy syntax like
444 # { 'count(foo.id)' => { '>' => 3 } } will stop working >:(
445 local $sql_maker->{quote_char} = $sql_maker->{quote_char};
446 local $sql_maker->{name_sep} = $sql_maker->{name_sep};
448 unless (defined $sql_maker->{quote_char} and length $sql_maker->{quote_char}) {
449 $sql_maker->{quote_char} = ["\x00", "\xFF"];
450 # if we don't unset it we screw up retarded but unfortunately working
451 # 'MAX(foo.bar)' => { '>', 3 }
452 $sql_maker->{name_sep} = '';
455 my ($lquote, $rquote, $sep) = map { quotemeta $_ } ($sql_maker->_quote_chars, $sql_maker->name_sep);
457 # generate sql chunks
460 $sql_maker->_recurse_where ($where),
461 $sql_maker->_parse_rs_attrs ({ having => $attrs->{having} }),
464 $sql_maker->_parse_rs_attrs ({ group_by => $attrs->{group_by} }),
467 $sql_maker->_recurse_from (
468 ref $from->[0] eq 'ARRAY' ? $from->[0][0] : $from->[0],
469 @{$from}[1 .. $#$from],
473 $sql_maker->_recurse_fields ($select),
476 map { $_->[0] } $self->_extract_order_criteria ($attrs->{order_by}, $sql_maker),
480 # throw away empty chunks
481 $_ = [ map { $_ || () } @$_ ] for values %$to_scan;
483 # first loop through all fully qualified columns and get the corresponding
484 # alias (should work even if they are in scalarrefs)
485 for my $alias (keys %$alias_list) {
487 $lquote $alias $rquote $sep (?: $lquote ([^$rquote]+) $rquote )?
489 \b $alias \. ([^\s\)\($rquote]+)?
492 for my $type (keys %$to_scan) {
493 for my $piece (@{$to_scan->{$type}}) {
494 if (my @matches = $piece =~ /$al_re/g) {
495 $aliases_by_type->{$type}{$alias} ||= { -parents => $alias_list->{$alias}{-join_path}||[] };
496 $aliases_by_type->{$type}{$alias}{-seen_columns}{"$alias.$_"} = "$alias.$_"
497 for grep { defined $_ } @matches;
503 # now loop through unqualified column names, and try to locate them within
505 for my $col (keys %$colinfo) {
506 next if $col =~ / \. /x; # if column is qualified it was caught by the above
508 my $col_re = qr/ $lquote ($col) $rquote /x;
510 for my $type (keys %$to_scan) {
511 for my $piece (@{$to_scan->{$type}}) {
512 if (my @matches = $piece =~ /$col_re/g) {
513 my $alias = $colinfo->{$col}{-source_alias};
514 $aliases_by_type->{$type}{$alias} ||= { -parents => $alias_list->{$alias}{-join_path}||[] };
515 $aliases_by_type->{$type}{$alias}{-seen_columns}{"$alias.$_"} = $_
516 for grep { defined $_ } @matches;
522 # Add any non-left joins to the restriction list (such joins are indeed restrictions)
523 for my $j (values %$alias_list) {
524 my $alias = $j->{-alias} or next;
525 $aliases_by_type->{restricting}{$alias} ||= { -parents => $j->{-join_path}||[] } if (
526 (not $j->{-join_type})
528 ($j->{-join_type} !~ /^left (?: \s+ outer)? $/xi)
532 for (keys %$aliases_by_type) {
533 delete $aliases_by_type->{$_} unless keys %{$aliases_by_type->{$_}};
536 return $aliases_by_type;
539 # This is the engine behind { distinct => 1 }
540 sub _group_over_selection {
541 my ($self, $from, $select, $order_by) = @_;
543 my $rs_column_list = $self->_resolve_column_info ($from);
545 my (@group_by, %group_index);
547 # the logic is: if it is a { func => val } we assume an aggregate,
548 # otherwise if \'...' or \[...] we assume the user knows what is
549 # going on thus group over it
551 if (! ref($_) or ref ($_) ne 'HASH' ) {
554 if ($rs_column_list->{$_} and $_ !~ /\./ ) {
555 # add a fully qualified version as well
556 $group_index{"$rs_column_list->{$_}{-source_alias}.$_"}++;
561 # add any order_by parts that are not already present in the group_by
562 # we need to be careful not to add any named functions/aggregates
563 # i.e. order_by => [ ... { count => 'foo' } ... ]
565 for ($self->_extract_order_criteria($order_by)) {
566 # only consider real columns (for functions the user got to do an explicit group_by)
572 my $colinfo = $rs_column_list->{$chunk} or do {
577 $chunk = "$colinfo->{-source_alias}.$chunk" if $chunk !~ /\./;
578 push @group_by, $chunk unless $group_index{$chunk}++;
582 ? (\@group_by, (@leftovers ? \@leftovers : undef) )
587 sub _resolve_ident_sources {
588 my ($self, $ident) = @_;
590 my $alias2source = {};
593 # the reason this is so contrived is that $ident may be a {from}
594 # structure, specifying multiple tables to join
595 if ( blessed $ident && $ident->isa("DBIx::Class::ResultSource") ) {
596 # this is compat mode for insert/update/delete which do not deal with aliases
597 $alias2source->{me} = $ident;
600 elsif (ref $ident eq 'ARRAY') {
604 if (ref $_ eq 'HASH') {
606 $rs_alias = $tabinfo->{-alias};
608 if (ref $_ eq 'ARRAY' and ref $_->[0] eq 'HASH') {
612 $alias2source->{$tabinfo->{-alias}} = $tabinfo->{-rsrc}
613 if ($tabinfo->{-rsrc});
617 return ($alias2source, $rs_alias);
620 # Takes $ident, \@column_names
622 # returns { $column_name => \%column_info, ... }
623 # also note: this adds -result_source => $rsrc to the column info
625 # If no columns_names are supplied returns info about *all* columns
627 sub _resolve_column_info {
628 my ($self, $ident, $colnames) = @_;
629 my ($alias2src, $root_alias) = $self->_resolve_ident_sources($ident);
631 my (%seen_cols, @auto_colnames);
633 # compile a global list of column names, to be able to properly
634 # disambiguate unqualified column names (if at all possible)
635 for my $alias (keys %$alias2src) {
636 my $rsrc = $alias2src->{$alias};
637 for my $colname ($rsrc->columns) {
638 push @{$seen_cols{$colname}}, $alias;
639 push @auto_colnames, "$alias.$colname" unless $colnames;
645 grep { @{$seen_cols{$_}} == 1 } (keys %seen_cols),
648 my (%return, $colinfos);
649 foreach my $col (@$colnames) {
650 my ($source_alias, $colname) = $col =~ m/^ (?: ([^\.]+) \. )? (.+) $/x;
652 # if the column was seen exactly once - we know which rsrc it came from
653 $source_alias ||= $seen_cols{$colname}[0]
654 if ($seen_cols{$colname} and @{$seen_cols{$colname}} == 1);
656 next unless $source_alias;
658 my $rsrc = $alias2src->{$source_alias}
663 ( $colinfos->{$source_alias} ||= $rsrc->columns_info )->{$colname}
665 $self->throw_exception(
666 "No such column '$colname' on source " . $rsrc->source_name
669 -result_source => $rsrc,
670 -source_alias => $source_alias,
671 -fq_colname => $col eq $colname ? "$source_alias.$col" : $col,
672 -colname => $colname,
675 $return{"$source_alias.$colname"} = $return{$col} if $col eq $colname;
681 # The DBIC relationship chaining implementation is pretty simple - every
682 # new related_relationship is pushed onto the {from} stack, and the {select}
683 # window simply slides further in. This means that when we count somewhere
684 # in the middle, we got to make sure that everything in the join chain is an
685 # actual inner join, otherwise the count will come back with unpredictable
686 # results (a resultset may be generated with _some_ rows regardless of if
687 # the relation which the $rs currently selects has rows or not). E.g.
688 # $artist_rs->cds->count - normally generates:
689 # SELECT COUNT( * ) FROM artist me LEFT JOIN cd cds ON cds.artist = me.artistid
690 # which actually returns the number of artists * (number of cds || 1)
692 # So what we do here is crawl {from}, determine if the current alias is at
693 # the top of the stack, and if not - make sure the chain is inner-joined down
696 sub _inner_join_to_node {
697 my ($self, $from, $alias) = @_;
699 # subqueries and other oddness are naturally not supported
705 ref $from->[0] ne 'HASH'
709 $from->[0]{-alias} eq $alias # this last bit means $alias is the head of $from - nothing to do
712 # find the current $alias in the $from structure
715 for my $j (@{$from}[1 .. $#$from]) {
716 if ($j->[0]{-alias} eq $alias) {
717 $switch_branch = $j->[0]{-join_path};
722 # something else went quite wrong
723 return $from unless $switch_branch;
725 # So it looks like we will have to switch some stuff around.
726 # local() is useless here as we will be leaving the scope
727 # anyway, and deep cloning is just too fucking expensive
728 # So replace the first hashref in the node arrayref manually
729 my @new_from = ($from->[0]);
730 my $sw_idx = { map { (values %$_), 1 } @$switch_branch }; #there's one k/v per join-path
732 for my $j (@{$from}[1 .. $#$from]) {
733 my $jalias = $j->[0]{-alias};
735 if ($sw_idx->{$jalias}) {
736 my %attrs = %{$j->[0]};
737 delete $attrs{-join_type};
751 sub _extract_order_criteria {
752 my ($self, $order_by, $sql_maker) = @_;
755 my ($sql_maker, $order_by) = @_;
757 return scalar $sql_maker->_order_by_chunks ($order_by)
761 for ($sql_maker->_order_by_chunks ($order_by) ) {
762 my $chunk = ref $_ ? $_ : [ $_ ];
763 $chunk->[0] =~ s/\s+ (?: ASC|DESC ) \s* $//ix;
764 push @chunks, $chunk;
771 return $parser->($sql_maker, $order_by);
774 $sql_maker = $self->sql_maker;
775 local $sql_maker->{quote_char};
776 return $parser->($sql_maker, $order_by);
780 sub _order_by_is_stable {
781 my ($self, $ident, $order_by, $where) = @_;
783 my $colinfo = $self->_resolve_column_info($ident, [
784 (map { $_->[0] } $self->_extract_order_criteria($order_by)),
785 $where ? @{$self->_extract_fixed_condition_columns($where)} :(),
788 return undef unless keys %$colinfo;
791 $cols_per_src->{$_->{-source_alias}}{$_->{-colname}} = $_ for values %$colinfo;
793 for (values %$cols_per_src) {
794 my $src = (values %$_)[0]->{-result_source};
795 return 1 if $src->_identifying_column_set($_);
801 # this is almost identical to the above, except it accepts only
802 # a single rsrc, and will succeed only if the first portion of the order
804 # returns that portion as a colinfo hashref on success
805 sub _main_source_order_by_portion_is_stable {
806 my ($self, $main_rsrc, $order_by, $where) = @_;
808 die "Huh... I expect a blessed result_source..."
809 if ref($main_rsrc) eq 'ARRAY';
813 ( $self->_extract_order_criteria($order_by) )
815 return unless @ord_cols;
817 my $colinfos = $self->_resolve_column_info($main_rsrc, \@ord_cols);
818 for (0 .. $#ord_cols) {
820 ! $colinfos->{$ord_cols[$_]}
822 $colinfos->{$ord_cols[$_]}{-result_source} != $main_rsrc
829 # we just truncated it above
830 return unless @ord_cols;
832 # since all we check here are the start of the order_by belonging to the
833 # top level $rsrc, a present identifying set will mean that the resultset
834 # is ordered by its leftmost table in a stable manner
836 # single source - safely use both qualified and unqualified name
837 my $order_portion_ci = { map {
838 $colinfos->{$_}{-colname} => $colinfos->{$_},
839 $colinfos->{$_}{-fq_colname} => $colinfos->{$_},
842 $where = $where ? $self->_resolve_column_info(
843 $main_rsrc, $self->_extract_fixed_condition_columns($where)
847 $main_rsrc->_identifying_column_set({ %$where, %$order_portion_ci })
853 # returns an arrayref of column names which *definitely* have som
854 # sort of non-nullable equality requested in the given condition
855 # specification. This is used to figure out if a resultset is
856 # constrained to a column which is part of a unique constraint,
857 # which in turn allows us to better predict how ordering will behave
860 # this is a rudimentary, incomplete, and error-prone extractor
861 # however this is OK - it is conservative, and if we can not find
862 # something that is in fact there - the stack will recover gracefully
863 # Also - DQ and the mst it rode in on will save us all RSN!!!
864 sub _extract_fixed_condition_columns {
865 my ($self, $where, $nested) = @_;
867 return unless ref $where eq 'HASH';
870 for my $lhs (keys %$where) {
871 if ($lhs =~ /^\-and$/i) {
872 push @cols, ref $where->{$lhs} eq 'ARRAY'
873 ? ( map { $self->_extract_fixed_condition_columns($_, 1) } @{$where->{$lhs}} )
874 : $self->_extract_fixed_condition_columns($where->{$lhs}, 1)
877 elsif ($lhs !~ /^\-/) {
878 my $val = $where->{$lhs};
880 push @cols, $lhs if (defined $val and (
883 (ref $val eq 'HASH' and keys %$val == 1 and defined $val->{'='})
887 return $nested ? @cols : \@cols;