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) = @_;
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 $attrs->{_force_prune_multiplying_joins} 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, $where, {
179 %$inner_attrs, _force_prune_multiplying_joins => 1
182 my $inner_aliastypes =
183 $self->_resolve_aliastypes_from_select_args( $inner_from, $inner_select, $where, $inner_attrs );
185 # uh-oh a multiplier (which is not us) left in, this is a problem
187 $inner_aliastypes->{multiplying}
189 !$inner_aliastypes->{grouping} # if there are groups - assume user knows wtf they are up to
191 my @multipliers = grep { $_ ne $root_alias } keys %{$inner_aliastypes->{multiplying}}
194 # if none of the multipliers came from an order_by (guaranteed to have been combined
195 # with a limit) - easy - just slap a group_by to simulate a collape and be on our way
197 ! $inner_aliastypes->{ordering}
199 ! first { $inner_aliastypes->{ordering}{$_} } @multipliers
202 my $unprocessed_order_chunks;
203 ($inner_attrs->{group_by}, $unprocessed_order_chunks) = $self->_group_over_selection (
204 $inner_from, $inner_select, $inner_attrs->{order_by}
207 $self->throw_exception (
208 'A required group_by clause could not be constructed automatically due to a complex '
209 . 'order_by criteria. Either order_by columns only (no functions) or construct a suitable '
211 ) if $unprocessed_order_chunks;
214 # We need to order by external columns and group at the same time
215 # so we can calculate the proper limit
216 # This doesn't really make sense in SQL, however from DBICs point
217 # of view is rather valid (order the leftmost objects by whatever
218 # criteria and get the offset/rows many). There is a way around
219 # this however in SQL - we simply tae the direction of each piece
220 # of the foreign order and convert them to MIN(X) for ASC or MAX(X)
221 # for DESC, and group_by the root columns. The end result should be
222 # exactly what we expect
224 # FIXME REMOVE LATER - (just a sanity check)
225 if (defined ( my $impostor = first
226 { $_ ne $root_alias }
227 keys %{ $inner_aliastypes->{selecting} }
229 $self->throw_exception(sprintf
230 'Unexpected inner selection during complex prefetch (%s)...',
231 join ', ', keys %{ $inner_aliastypes->{joining}{$impostor}{-seen_columns} || {} }
235 # supplement the main selection with pks if not already there,
236 # as they will have to be a part of the group_by to colapse
238 my $cur_sel = { map { $_ => 1 } @$inner_select };
240 my @pks = map { "$root_alias.$_" } $root_node->{-rsrc}->primary_columns
241 or $self->throw_exception( sprintf
242 'Unable to perform complex limited prefetch off %s without declared primary key',
243 $root_node->{-rsrc}->source_name,
246 push @$inner_select, $col
247 unless $cur_sel->{$col}++;
250 # wrap any part of the order_by that "responds" to an ordering alias
252 # FIXME - this code is a joke, will need to be completely rewritten in
253 # the DQ branch. But I need to push a POC here, otherwise the
254 # pesky tests won't pass
255 my $sql_maker = $self->sql_maker;
256 my ($lquote, $rquote, $sep) = map { quotemeta $_ } ($sql_maker->_quote_chars, $sql_maker->name_sep);
257 my $own_re = qr/ $lquote \Q$root_alias\E $rquote $sep | \b \Q$root_alias\E $sep /x;
258 my @order_chunks = map { ref $_ eq 'ARRAY' ? $_ : [ $_ ] } $sql_maker->_order_by_chunks($attrs->{order_by});
259 my @new_order = map { \$_ } @order_chunks;
260 my $inner_columns_info = $self->_resolve_column_info($inner_from);
262 # loop through and replace stuff that is not "ours" with a min/max func
263 # everything is a literal at this point, since we are likely properly
265 for my $i (0 .. $#new_order) {
266 my $chunk = $order_chunks[$i][0];
269 next if $chunk =~ $own_re;
271 ($chunk, my $is_desc) = $sql_maker->_split_order_chunk($chunk);
273 # maybe our own unqualified column
275 $lquote and $sep and $chunk =~ /^ $lquote ([^$sep]+) $rquote $/x
281 $inner_columns_info->{$ord_bit}
283 $inner_columns_info->{$ord_bit}{-source_alias} eq $root_alias
289 ($is_desc ? 'MAX' : 'MIN'),
291 ($is_desc ? ' DESC' : ''),
293 @ {$order_chunks[$i]} [ 1 .. $#{$order_chunks[$i]} ]
297 $inner_attrs->{order_by} = \@new_order;
299 # do not care about leftovers here - it will be all the functions
301 ($inner_attrs->{group_by}) = $self->_group_over_selection (
302 $inner_from, $inner_select, $inner_attrs->{order_by}
307 # we already optimized $inner_from above
308 # and already local()ized
309 $self->{_use_join_optimizer} = 0;
311 # generate the subquery
312 $self->_select_args_to_query (
320 # Generate the outer from - this is relatively easy (really just replace
321 # the join slot with the subquery), with a major caveat - we can not
322 # join anything that is non-selecting (not part of the prefetch), but at
323 # the same time is a multi-type relationship, as it will explode the result.
325 # There are two possibilities here
326 # - either the join is non-restricting, in which case we simply throw it away
327 # - it is part of the restrictions, in which case we need to collapse the outer
328 # result by tackling yet another group_by to the outside of the query
330 # work on a shallow copy
335 # we may not be the head
336 if ($root_node_offset) {
337 # first generate the outer_from, up to the substitution point
338 @outer_from = splice @$from, 0, $root_node_offset;
342 -alias => $root_alias,
343 -rsrc => $root_node->{-rsrc},
344 $root_alias => $inner_subq,
346 @{$from->[0]}[1 .. $#{$from->[0]}],
351 -alias => $root_alias,
352 -rsrc => $root_node->{-rsrc},
353 $root_alias => $inner_subq,
357 shift @$from; # it's replaced in @outer_from already
359 # scan the *remaining* from spec against different attributes, and see which joins are needed
361 my $outer_aliastypes =
362 $self->_resolve_aliastypes_from_select_args( $from, $outer_select, $where, $outer_attrs );
365 my ($outer_select_chain, @outer_nonselecting_chains) = map { +{
366 map { $_ => 1 } map { values %$_} map { @{$_->{-parents}} } values %{ $outer_aliastypes->{$_} || {} }
367 } } qw/selecting restricting grouping ordering/;
369 # see what's left - throw away if not selecting/restricting
370 # also throw in a group_by if a non-selecting multiplier,
371 # to guard against cross-join explosions
372 my $need_outer_group_by;
373 while (my $j = shift @$from) {
374 my $alias = $j->[0]{-alias};
377 $outer_select_chain->{$alias}
381 elsif (first { $_->{$alias} } @outer_nonselecting_chains ) {
382 push @outer_from, $j;
383 $need_outer_group_by ||= $outer_aliastypes->{multiplying}{$alias} ? 1 : 0;
387 if ( $need_outer_group_by and $attrs->{_grouped_by_distinct} ) {
388 my $unprocessed_order_chunks;
389 ($outer_attrs->{group_by}, $unprocessed_order_chunks) = $self->_group_over_selection (
390 \@outer_from, $outer_select, $outer_attrs->{order_by}
393 $self->throw_exception (
394 'A required group_by clause could not be constructed automatically due to a complex '
395 . 'order_by criteria. Either order_by columns only (no functions) or construct a suitable '
397 ) if $unprocessed_order_chunks;
401 # This is totally horrific - the $where ends up in both the inner and outer query
402 # Unfortunately not much can be done until SQLA2 introspection arrives, and even
403 # then if where conditions apply to the *right* side of the prefetch, you may have
404 # to both filter the inner select (e.g. to apply a limit) and then have to re-filter
405 # the outer select to exclude joins you didin't want in the first place
407 # OTOH it can be seen as a plus: <ash> (notes that this query would make a DBA cry ;)
408 return (\@outer_from, $outer_select, $where, $outer_attrs);
412 # I KNOW THIS SUCKS! GET SQLA2 OUT THE DOOR SO THIS CAN DIE!
414 # Due to a lack of SQLA2 we fall back to crude scans of all the
415 # select/where/order/group attributes, in order to determine what
416 # aliases are neded to fulfill the query. This information is used
417 # throughout the code to prune unnecessary JOINs from the queries
418 # in an attempt to reduce the execution time.
419 # Although the method is pretty horrific, the worst thing that can
420 # happen is for it to fail due to some scalar SQL, which in turn will
421 # result in a vocal exception.
422 sub _resolve_aliastypes_from_select_args {
423 my ( $self, $from, $select, $where, $attrs ) = @_;
425 $self->throw_exception ('Unable to analyze custom {from}')
426 if ref $from ne 'ARRAY';
428 # what we will return
431 # see what aliases are there to work with
435 $j = $j->[0] if ref $j eq 'ARRAY';
436 my $al = $j->{-alias}
439 $alias_list->{$al} = $j;
440 $aliases_by_type->{multiplying}{$al} ||= { -parents => $j->{-join_path}||[] } if (
441 # not array == {from} head == can't be multiplying
442 ( ref($_) eq 'ARRAY' and ! $j->{-is_single} )
444 # a parent of ours is already a multiplier
445 ( grep { $aliases_by_type->{multiplying}{$_} } @{ $j->{-join_path}||[] } )
449 # get a column to source/alias map (including unambiguous unqualified ones)
450 my $colinfo = $self->_resolve_column_info ($from);
452 # set up a botched SQLA
453 my $sql_maker = $self->sql_maker;
455 # these are throw away results, do not pollute the bind stack
456 local $sql_maker->{select_bind};
457 local $sql_maker->{where_bind};
458 local $sql_maker->{group_bind};
459 local $sql_maker->{having_bind};
460 local $sql_maker->{from_bind};
462 # we can't scan properly without any quoting (\b doesn't cut it
463 # everywhere), so unless there is proper quoting set - use our
464 # own weird impossible character.
465 # Also in the case of no quoting, we need to explicitly disable
466 # name_sep, otherwise sorry nasty legacy syntax like
467 # { 'count(foo.id)' => { '>' => 3 } } will stop working >:(
468 local $sql_maker->{quote_char} = $sql_maker->{quote_char};
469 local $sql_maker->{name_sep} = $sql_maker->{name_sep};
471 unless (defined $sql_maker->{quote_char} and length $sql_maker->{quote_char}) {
472 $sql_maker->{quote_char} = ["\x00", "\xFF"];
473 # if we don't unset it we screw up retarded but unfortunately working
474 # 'MAX(foo.bar)' => { '>', 3 }
475 $sql_maker->{name_sep} = '';
478 my ($lquote, $rquote, $sep) = map { quotemeta $_ } ($sql_maker->_quote_chars, $sql_maker->name_sep);
480 # generate sql chunks
483 $sql_maker->_recurse_where ($where),
484 $sql_maker->_parse_rs_attrs ({ having => $attrs->{having} }),
487 $sql_maker->_parse_rs_attrs ({ group_by => $attrs->{group_by} }),
490 $sql_maker->_recurse_from (
491 ref $from->[0] eq 'ARRAY' ? $from->[0][0] : $from->[0],
492 @{$from}[1 .. $#$from],
496 $sql_maker->_recurse_fields ($select),
499 map { $_->[0] } $self->_extract_order_criteria ($attrs->{order_by}, $sql_maker),
503 # throw away empty chunks
504 $_ = [ map { $_ || () } @$_ ] for values %$to_scan;
506 # first see if we have any exact matches (qualified or unqualified)
507 for my $type (keys %$to_scan) {
508 for my $piece (@{$to_scan->{$type}}) {
509 if ($colinfo->{$piece} and my $alias = $colinfo->{$piece}{-source_alias}) {
510 $aliases_by_type->{$type}{$alias} ||= { -parents => $alias_list->{$alias}{-join_path}||[] };
511 $aliases_by_type->{$type}{$alias}{-seen_columns}{$colinfo->{$piece}{-fq_colname}} = $piece;
516 # now loop through all fully qualified columns and get the corresponding
517 # alias (should work even if they are in scalarrefs)
518 for my $alias (keys %$alias_list) {
520 $lquote $alias $rquote $sep (?: $lquote ([^$rquote]+) $rquote )?
522 \b $alias \. ([^\s\)\($rquote]+)?
525 for my $type (keys %$to_scan) {
526 for my $piece (@{$to_scan->{$type}}) {
527 if (my @matches = $piece =~ /$al_re/g) {
528 $aliases_by_type->{$type}{$alias} ||= { -parents => $alias_list->{$alias}{-join_path}||[] };
529 $aliases_by_type->{$type}{$alias}{-seen_columns}{"$alias.$_"} = "$alias.$_"
530 for grep { defined $_ } @matches;
536 # now loop through unqualified column names, and try to locate them within
538 for my $col (keys %$colinfo) {
539 next if $col =~ / \. /x; # if column is qualified it was caught by the above
541 my $col_re = qr/ $lquote ($col) $rquote /x;
543 for my $type (keys %$to_scan) {
544 for my $piece (@{$to_scan->{$type}}) {
545 if ( my @matches = $piece =~ /$col_re/g) {
546 my $alias = $colinfo->{$col}{-source_alias};
547 $aliases_by_type->{$type}{$alias} ||= { -parents => $alias_list->{$alias}{-join_path}||[] };
548 $aliases_by_type->{$type}{$alias}{-seen_columns}{"$alias.$_"} = $_
549 for grep { defined $_ } @matches;
555 # Add any non-left joins to the restriction list (such joins are indeed restrictions)
556 for my $j (values %$alias_list) {
557 my $alias = $j->{-alias} or next;
558 $aliases_by_type->{restricting}{$alias} ||= { -parents => $j->{-join_path}||[] } if (
559 (not $j->{-join_type})
561 ($j->{-join_type} !~ /^left (?: \s+ outer)? $/xi)
565 for (keys %$aliases_by_type) {
566 delete $aliases_by_type->{$_} unless keys %{$aliases_by_type->{$_}};
569 return $aliases_by_type;
572 # This is the engine behind { distinct => 1 }
573 sub _group_over_selection {
574 my ($self, $from, $select, $order_by) = @_;
576 my $rs_column_list = $self->_resolve_column_info ($from);
578 my (@group_by, %group_index);
580 # the logic is: if it is a { func => val } we assume an aggregate,
581 # otherwise if \'...' or \[...] we assume the user knows what is
582 # going on thus group over it
584 if (! ref($_) or ref ($_) ne 'HASH' ) {
587 if ($rs_column_list->{$_} and $_ !~ /\./ ) {
588 # add a fully qualified version as well
589 $group_index{"$rs_column_list->{$_}{-source_alias}.$_"}++;
594 # add any order_by parts that are not already present in the group_by
595 # we need to be careful not to add any named functions/aggregates
596 # i.e. order_by => [ ... { count => 'foo' } ... ]
598 for ($self->_extract_order_criteria($order_by)) {
599 # only consider real columns (for functions the user got to do an explicit group_by)
605 my $colinfo = $rs_column_list->{$chunk} or do {
610 $chunk = "$colinfo->{-source_alias}.$chunk" if $chunk !~ /\./;
611 push @group_by, $chunk unless $group_index{$chunk}++;
615 ? (\@group_by, (@leftovers ? \@leftovers : undef) )
620 sub _resolve_ident_sources {
621 my ($self, $ident) = @_;
623 my $alias2source = {};
625 # the reason this is so contrived is that $ident may be a {from}
626 # structure, specifying multiple tables to join
627 if ( blessed $ident && $ident->isa("DBIx::Class::ResultSource") ) {
628 # this is compat mode for insert/update/delete which do not deal with aliases
629 $alias2source->{me} = $ident;
631 elsif (ref $ident eq 'ARRAY') {
635 if (ref $_ eq 'HASH') {
638 if (ref $_ eq 'ARRAY' and ref $_->[0] eq 'HASH') {
642 $alias2source->{$tabinfo->{-alias}} = $tabinfo->{-rsrc}
643 if ($tabinfo->{-rsrc});
647 return $alias2source;
650 # Takes $ident, \@column_names
652 # returns { $column_name => \%column_info, ... }
653 # also note: this adds -result_source => $rsrc to the column info
655 # If no columns_names are supplied returns info about *all* columns
657 sub _resolve_column_info {
658 my ($self, $ident, $colnames) = @_;
659 my $alias2src = $self->_resolve_ident_sources($ident);
661 my (%seen_cols, @auto_colnames);
663 # compile a global list of column names, to be able to properly
664 # disambiguate unqualified column names (if at all possible)
665 for my $alias (keys %$alias2src) {
666 my $rsrc = $alias2src->{$alias};
667 for my $colname ($rsrc->columns) {
668 push @{$seen_cols{$colname}}, $alias;
669 push @auto_colnames, "$alias.$colname" unless $colnames;
675 grep { @{$seen_cols{$_}} == 1 } (keys %seen_cols),
678 my (%return, $colinfos);
679 foreach my $col (@$colnames) {
680 my ($source_alias, $colname) = $col =~ m/^ (?: ([^\.]+) \. )? (.+) $/x;
682 # if the column was seen exactly once - we know which rsrc it came from
683 $source_alias ||= $seen_cols{$colname}[0]
684 if ($seen_cols{$colname} and @{$seen_cols{$colname}} == 1);
686 next unless $source_alias;
688 my $rsrc = $alias2src->{$source_alias}
693 ( $colinfos->{$source_alias} ||= $rsrc->columns_info )->{$colname}
695 $self->throw_exception(
696 "No such column '$colname' on source " . $rsrc->source_name
699 -result_source => $rsrc,
700 -source_alias => $source_alias,
701 -fq_colname => $col eq $colname ? "$source_alias.$col" : $col,
702 -colname => $colname,
705 $return{"$source_alias.$colname"} = $return{$col} if $col eq $colname;
711 # The DBIC relationship chaining implementation is pretty simple - every
712 # new related_relationship is pushed onto the {from} stack, and the {select}
713 # window simply slides further in. This means that when we count somewhere
714 # in the middle, we got to make sure that everything in the join chain is an
715 # actual inner join, otherwise the count will come back with unpredictable
716 # results (a resultset may be generated with _some_ rows regardless of if
717 # the relation which the $rs currently selects has rows or not). E.g.
718 # $artist_rs->cds->count - normally generates:
719 # SELECT COUNT( * ) FROM artist me LEFT JOIN cd cds ON cds.artist = me.artistid
720 # which actually returns the number of artists * (number of cds || 1)
722 # So what we do here is crawl {from}, determine if the current alias is at
723 # the top of the stack, and if not - make sure the chain is inner-joined down
726 sub _inner_join_to_node {
727 my ($self, $from, $alias) = @_;
729 # subqueries and other oddness are naturally not supported
735 ref $from->[0] ne 'HASH'
739 $from->[0]{-alias} eq $alias # this last bit means $alias is the head of $from - nothing to do
742 # find the current $alias in the $from structure
745 for my $j (@{$from}[1 .. $#$from]) {
746 if ($j->[0]{-alias} eq $alias) {
747 $switch_branch = $j->[0]{-join_path};
752 # something else went quite wrong
753 return $from unless $switch_branch;
755 # So it looks like we will have to switch some stuff around.
756 # local() is useless here as we will be leaving the scope
757 # anyway, and deep cloning is just too fucking expensive
758 # So replace the first hashref in the node arrayref manually
759 my @new_from = ($from->[0]);
760 my $sw_idx = { map { (values %$_), 1 } @$switch_branch }; #there's one k/v per join-path
762 for my $j (@{$from}[1 .. $#$from]) {
763 my $jalias = $j->[0]{-alias};
765 if ($sw_idx->{$jalias}) {
766 my %attrs = %{$j->[0]};
767 delete $attrs{-join_type};
781 sub _extract_order_criteria {
782 my ($self, $order_by, $sql_maker) = @_;
785 my ($sql_maker, $order_by, $orig_quote_chars) = @_;
787 return scalar $sql_maker->_order_by_chunks ($order_by)
790 my ($lq, $rq, $sep) = map { quotemeta($_) } (
791 ($orig_quote_chars ? @$orig_quote_chars : $sql_maker->_quote_chars),
796 for ($sql_maker->_order_by_chunks ($order_by) ) {
797 my $chunk = ref $_ ? [ @$_ ] : [ $_ ];
798 ($chunk->[0]) = $sql_maker->_split_order_chunk($chunk->[0]);
800 # order criteria may have come back pre-quoted (literals and whatnot)
801 # this is fragile, but the best we can currently do
802 $chunk->[0] =~ s/^ $lq (.+?) $rq $sep $lq (.+?) $rq $/"$1.$2"/xe
803 or $chunk->[0] =~ s/^ $lq (.+) $rq $/$1/x;
805 push @chunks, $chunk;
812 return $parser->($sql_maker, $order_by);
815 $sql_maker = $self->sql_maker;
817 # pass these in to deal with literals coming from
818 # the user or the deep guts of prefetch
819 my $orig_quote_chars = [$sql_maker->_quote_chars];
821 local $sql_maker->{quote_char};
822 return $parser->($sql_maker, $order_by, $orig_quote_chars);
826 sub _order_by_is_stable {
827 my ($self, $ident, $order_by, $where) = @_;
829 my $colinfo = $self->_resolve_column_info($ident, [
830 (map { $_->[0] } $self->_extract_order_criteria($order_by)),
831 $where ? @{$self->_extract_fixed_condition_columns($where)} :(),
834 return undef unless keys %$colinfo;
837 $cols_per_src->{$_->{-source_alias}}{$_->{-colname}} = $_ for values %$colinfo;
839 for (values %$cols_per_src) {
840 my $src = (values %$_)[0]->{-result_source};
841 return 1 if $src->_identifying_column_set($_);
847 # this is almost identical to the above, except it accepts only
848 # a single rsrc, and will succeed only if the first portion of the order
850 # returns that portion as a colinfo hashref on success
851 sub _main_source_order_by_portion_is_stable {
852 my ($self, $main_rsrc, $order_by, $where) = @_;
854 die "Huh... I expect a blessed result_source..."
855 if ref($main_rsrc) eq 'ARRAY';
859 ( $self->_extract_order_criteria($order_by) )
861 return unless @ord_cols;
863 my $colinfos = $self->_resolve_column_info($main_rsrc);
865 for (0 .. $#ord_cols) {
867 ! $colinfos->{$ord_cols[$_]}
869 $colinfos->{$ord_cols[$_]}{-result_source} != $main_rsrc
876 # we just truncated it above
877 return unless @ord_cols;
879 my $order_portion_ci = { map {
880 $colinfos->{$_}{-colname} => $colinfos->{$_},
881 $colinfos->{$_}{-fq_colname} => $colinfos->{$_},
884 # since all we check here are the start of the order_by belonging to the
885 # top level $rsrc, a present identifying set will mean that the resultset
886 # is ordered by its leftmost table in a stable manner
888 # RV of _identifying_column_set contains unqualified names only
889 my $unqualified_idset = $main_rsrc->_identifying_column_set({
891 $self->_resolve_column_info(
892 $main_rsrc, $self->_extract_fixed_condition_columns($where)
899 my %unqualified_idcols_from_order = map {
900 $order_portion_ci->{$_} ? ( $_ => $order_portion_ci->{$_} ) : ()
901 } @$unqualified_idset;
903 # extra optimization - cut the order_by at the end of the identifying set
904 # (just in case the user was stupid and overlooked the obvious)
905 for my $i (0 .. $#ord_cols) {
906 my $col = $ord_cols[$i];
907 my $unqualified_colname = $order_portion_ci->{$col}{-colname};
908 $ret_info->{$col} = { %{$order_portion_ci->{$col}}, -idx_in_order_subset => $i };
909 delete $unqualified_idcols_from_order{$ret_info->{$col}{-colname}};
911 # we didn't reach the end of the identifying portion yet
912 return $ret_info unless keys %unqualified_idcols_from_order;
915 die 'How did we get here...';
918 # returns an arrayref of column names which *definitely* have som
919 # sort of non-nullable equality requested in the given condition
920 # specification. This is used to figure out if a resultset is
921 # constrained to a column which is part of a unique constraint,
922 # which in turn allows us to better predict how ordering will behave
925 # this is a rudimentary, incomplete, and error-prone extractor
926 # however this is OK - it is conservative, and if we can not find
927 # something that is in fact there - the stack will recover gracefully
928 # Also - DQ and the mst it rode in on will save us all RSN!!!
929 sub _extract_fixed_condition_columns {
930 my ($self, $where, $nested) = @_;
932 return unless ref $where eq 'HASH';
935 for my $lhs (keys %$where) {
936 if ($lhs =~ /^\-and$/i) {
937 push @cols, ref $where->{$lhs} eq 'ARRAY'
938 ? ( map { $self->_extract_fixed_condition_columns($_, 1) } @{$where->{$lhs}} )
939 : $self->_extract_fixed_condition_columns($where->{$lhs}, 1)
942 elsif ($lhs !~ /^\-/) {
943 my $val = $where->{$lhs};
945 push @cols, $lhs if (defined $val and (
948 (ref $val eq 'HASH' and keys %$val == 1 and defined $val->{'='})
952 return $nested ? @cols : \@cols;