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 {
26 my ($self, $attrs) = @_;
28 # only standard {from} specs are supported, and we could be disabled in general
29 return ($attrs->{from}, {}) unless (
30 ref $attrs->{from} eq 'ARRAY'
34 ref $attrs->{from}[0] eq 'HASH'
36 ref $attrs->{from}[1] eq 'ARRAY'
38 $self->_use_join_optimizer
41 my $aliastypes = $self->_resolve_aliastypes_from_select_args($attrs);
43 my $orig_joins = delete $aliastypes->{joining};
44 my $orig_multiplying = $aliastypes->{multiplying};
46 # a grouped set will not be affected by amount of rows. Thus any
47 # {multiplying} joins can go
48 delete $aliastypes->{multiplying}
49 if $attrs->{_force_prune_multiplying_joins} or $attrs->{group_by};
51 my @newfrom = $attrs->{from}[0]; # FROM head is always present
55 for (values %$aliastypes) {
56 # add all requested aliases
57 $need_joins{$_} = 1 for keys %$_;
59 # add all their parents (as per joinpath which is an AoH { table => alias })
60 $need_joins{$_} = 1 for map { values %$_ } map { @{$_->{-parents}} } values %$_;
63 for my $j (@{$attrs->{from}}[1..$#{$attrs->{from}}]) {
64 push @newfrom, $j if (
65 (! defined $j->[0]{-alias}) # legacy crap
67 $need_joins{$j->[0]{-alias}}
72 multiplying => { map { $need_joins{$_} ? ($_ => $orig_multiplying->{$_}) : () } keys %$orig_multiplying },
74 joining => { map { $_ => $orig_joins->{$_} } keys %need_joins },
79 # This is the code producing joined subqueries like:
80 # SELECT me.*, other.* FROM ( SELECT me.* FROM ... ) JOIN other ON ...
82 sub _adjust_select_args_for_complex_prefetch {
83 my ($self, $attrs) = @_;
85 $self->throw_exception ('Complex prefetches are not supported on resultsets with a custom from attribute') unless (
86 ref $attrs->{from} eq 'ARRAY'
90 ref $attrs->{from}[0] eq 'HASH'
92 ref $attrs->{from}[1] eq 'ARRAY'
95 my $root_alias = $attrs->{alias};
97 # generate inner/outer attribute lists, remove stuff that doesn't apply
98 my $outer_attrs = { %$attrs };
99 delete @{$outer_attrs}{qw(from bind rows offset group_by _grouped_by_distinct having)};
101 my $inner_attrs = { %$attrs };
102 delete @{$inner_attrs}{qw(for collapse select as _related_results_construction)};
104 # there is no point of ordering the insides if there is no limit
105 delete $inner_attrs->{order_by} if (
106 delete $inner_attrs->{_order_is_artificial}
108 ! $inner_attrs->{rows}
111 # generate the inner/outer select lists
112 # for inside we consider only stuff *not* brought in by the prefetch
113 # on the outside we substitute any function for its alias
114 $outer_attrs->{select} = [ @{$attrs->{select}} ];
116 my ($root_node, $root_node_offset);
118 for my $i (0 .. $#{$inner_attrs->{from}}) {
119 my $node = $inner_attrs->{from}[$i];
120 my $h = (ref $node eq 'HASH') ? $node
121 : (ref $node eq 'ARRAY' and ref $node->[0] eq 'HASH') ? $node->[0]
125 if ( ($h->{-alias}||'') eq $root_alias and $h->{-rsrc} ) {
127 $root_node_offset = $i;
132 $self->throw_exception ('Complex prefetches are not supported on resultsets with a custom from attribute')
135 # use the heavy duty resolver to take care of aliased/nonaliased naming
136 my $colinfo = $self->_resolve_column_info($inner_attrs->{from});
137 my $selected_root_columns;
139 for my $i (0 .. $#{$outer_attrs->{select}}) {
140 my $sel = $outer_attrs->{select}->[$i];
143 $colinfo->{$sel} and $colinfo->{$sel}{-source_alias} ne $root_alias
146 if (ref $sel eq 'HASH' ) {
147 $sel->{-as} ||= $attrs->{as}[$i];
148 $outer_attrs->{select}->[$i] = join ('.', $root_alias, ($sel->{-as} || "inner_column_$i") );
150 elsif (! ref $sel and my $ci = $colinfo->{$sel}) {
151 $selected_root_columns->{$ci->{-colname}} = 1;
154 push @{$inner_attrs->{select}}, $sel;
156 push @{$inner_attrs->{as}}, $attrs->{as}[$i];
159 # We will need to fetch all native columns in the inner subquery, which may
160 # be a part of an *outer* join condition, or an order_by (which needs to be
161 # preserved outside), or wheres. In other words everything but the inner
163 # We can not just fetch everything because a potential has_many restricting
164 # join collapse *will not work* on heavy data types.
165 my $connecting_aliastypes = $self->_resolve_aliastypes_from_select_args({
170 for (sort map { keys %{$_->{-seen_columns}||{}} } map { values %$_ } values %$connecting_aliastypes) {
171 my $ci = $colinfo->{$_} or next;
173 $ci->{-source_alias} eq $root_alias
175 ! $selected_root_columns->{$ci->{-colname}}++
177 # adding it to both to keep limits not supporting dark selectors happy
178 push @{$inner_attrs->{select}}, $ci->{-fq_colname};
179 push @{$inner_attrs->{as}}, $ci->{-fq_colname};
183 # construct the inner {from} and lock it in a subquery
184 # we need to prune first, because this will determine if we need a group_by below
185 # throw away all non-selecting, non-restricting multijoins
186 # (since we def. do not care about multiplication those inside the subquery)
187 my $inner_subq = do {
189 # must use it here regardless of user requests
190 local $self->{_use_join_optimizer} = 1;
192 # throw away multijoins since we def. do not care about those inside the subquery
193 ($inner_attrs->{from}, my $inner_aliastypes) = $self->_prune_unused_joins ({
194 %$inner_attrs, _force_prune_multiplying_joins => 1
197 # uh-oh a multiplier (which is not us) left in, this is a problem
199 $inner_aliastypes->{multiplying}
201 # if there are user-supplied groups - assume user knows wtf they are up to
202 ( ! $inner_aliastypes->{grouping} or $inner_attrs->{_grouped_by_distinct} )
204 my @multipliers = grep { $_ ne $root_alias } keys %{$inner_aliastypes->{multiplying}}
207 # if none of the multipliers came from an order_by (guaranteed to have been combined
208 # with a limit) - easy - just slap a group_by to simulate a collapse and be on our way
210 ! $inner_aliastypes->{ordering}
212 ! first { $inner_aliastypes->{ordering}{$_} } @multipliers
215 my $unprocessed_order_chunks;
216 ($inner_attrs->{group_by}, $unprocessed_order_chunks) = $self->_group_over_selection (
220 $self->throw_exception (
221 'A required group_by clause could not be constructed automatically due to a complex '
222 . 'order_by criteria. Either order_by columns only (no functions) or construct a suitable '
224 ) if $unprocessed_order_chunks;
227 # We need to order by external columns and group at the same time
228 # so we can calculate the proper limit
229 # This doesn't really make sense in SQL, however from DBICs point
230 # of view is rather valid (order the leftmost objects by whatever
231 # criteria and get the offset/rows many). There is a way around
232 # this however in SQL - we simply tae the direction of each piece
233 # of the foreign order and convert them to MIN(X) for ASC or MAX(X)
234 # for DESC, and group_by the root columns. The end result should be
235 # exactly what we expect
237 # supplement the main selection with pks if not already there,
238 # as they will have to be a part of the group_by to collapse
240 my $cur_sel = { map { $_ => 1 } @{$inner_attrs->{select}} };
242 my @pks = map { "$root_alias.$_" } $root_node->{-rsrc}->primary_columns
243 or $self->throw_exception( sprintf
244 'Unable to perform complex limited prefetch off %s without declared primary key',
245 $root_node->{-rsrc}->source_name,
248 push @{$inner_attrs->{select}}, $col
249 unless $cur_sel->{$col}++;
252 # wrap any part of the order_by that "responds" to an ordering alias
254 # FIXME - this code is a joke, will need to be completely rewritten in
255 # the DQ branch. But I need to push a POC here, otherwise the
256 # pesky tests won't pass
257 my $sql_maker = $self->sql_maker;
258 my ($lquote, $rquote, $sep) = map { quotemeta $_ } ($sql_maker->_quote_chars, $sql_maker->name_sep);
259 my $own_re = qr/ $lquote \Q$root_alias\E $rquote $sep | \b \Q$root_alias\E $sep /x;
260 my @order_chunks = map { ref $_ eq 'ARRAY' ? $_ : [ $_ ] } $sql_maker->_order_by_chunks($attrs->{order_by});
261 my @new_order = map { \$_ } @order_chunks;
262 my $inner_columns_info = $self->_resolve_column_info($inner_attrs->{from});
264 # loop through and replace stuff that is not "ours" with a min/max func
265 # everything is a literal at this point, since we are likely properly
267 for my $i (0 .. $#new_order) {
268 my $chunk = $order_chunks[$i][0];
271 next if $chunk =~ $own_re;
273 ($chunk, my $is_desc) = $sql_maker->_split_order_chunk($chunk);
275 # maybe our own unqualified column
277 $lquote and $sep and $chunk =~ /^ $lquote ([^$sep]+) $rquote $/x
283 $inner_columns_info->{$ord_bit}
285 $inner_columns_info->{$ord_bit}{-source_alias} eq $root_alias
291 ($is_desc ? 'MAX' : 'MIN'),
293 ($is_desc ? ' DESC' : ''),
295 @ {$order_chunks[$i]} [ 1 .. $#{$order_chunks[$i]} ]
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 (
309 # we already optimized $inner_attrs->{from} above
310 # and already local()ized
311 $self->{_use_join_optimizer} = 0;
313 # generate the subquery
314 $self->_select_args_to_query (
315 @{$inner_attrs}{qw(from select where)},
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
331 my @orig_from = @{$attrs->{from}};
334 $outer_attrs->{from} = \ my @outer_from;
336 # we may not be the head
337 if ($root_node_offset) {
338 # first generate the outer_from, up to the substitution point
339 @outer_from = splice @orig_from, 0, $root_node_offset;
341 # substitute the subq at the right spot
344 -alias => $root_alias,
345 -rsrc => $root_node->{-rsrc},
346 $root_alias => $inner_subq,
348 # preserve attrs from what is now the head of the from after the splice
349 @{$orig_from[0]}[1 .. $#{$orig_from[0]}],
354 -alias => $root_alias,
355 -rsrc => $root_node->{-rsrc},
356 $root_alias => $inner_subq,
360 shift @orig_from; # what we just replaced above
362 # scan the *remaining* from spec against different attributes, and see which joins are needed
364 my $outer_aliastypes = $outer_attrs->{_aliastypes} =
365 $self->_resolve_aliastypes_from_select_args({ %$outer_attrs, from => \@orig_from });
368 my ($outer_select_chain, @outer_nonselecting_chains) = map { +{
369 map { $_ => 1 } map { values %$_} map { @{$_->{-parents}} } values %{ $outer_aliastypes->{$_} || {} }
370 } } qw/selecting restricting grouping ordering/;
372 # see what's left - throw away if not selecting/restricting
373 # also throw in a group_by if a non-selecting multiplier,
374 # to guard against cross-join explosions
375 my $need_outer_group_by;
376 while (my $j = shift @orig_from) {
377 my $alias = $j->[0]{-alias};
380 $outer_select_chain->{$alias}
384 elsif (first { $_->{$alias} } @outer_nonselecting_chains ) {
385 push @outer_from, $j;
386 $need_outer_group_by ||= $outer_aliastypes->{multiplying}{$alias} ? 1 : 0;
390 if ( $need_outer_group_by and $attrs->{_grouped_by_distinct} ) {
391 my $unprocessed_order_chunks;
392 ($outer_attrs->{group_by}, $unprocessed_order_chunks) = $self->_group_over_selection ({
394 from => \@outer_from,
397 $self->throw_exception (
398 'A required group_by clause could not be constructed automatically due to a complex '
399 . 'order_by criteria. Either order_by columns only (no functions) or construct a suitable '
401 ) if $unprocessed_order_chunks;
405 # This is totally horrific - the {where} ends up in both the inner and outer query
406 # Unfortunately not much can be done until SQLA2 introspection arrives, and even
407 # then if where conditions apply to the *right* side of the prefetch, you may have
408 # to both filter the inner select (e.g. to apply a limit) and then have to re-filter
409 # the outer select to exclude joins you didn't want in the first place
411 # OTOH it can be seen as a plus: <ash> (notes that this query would make a DBA cry ;)
417 # I KNOW THIS SUCKS! GET SQLA2 OUT THE DOOR SO THIS CAN DIE!
419 # Due to a lack of SQLA2 we fall back to crude scans of all the
420 # select/where/order/group attributes, in order to determine what
421 # aliases are needed to fulfill the query. This information is used
422 # throughout the code to prune unnecessary JOINs from the queries
423 # in an attempt to reduce the execution time.
424 # Although the method is pretty horrific, the worst thing that can
425 # happen is for it to fail due to some scalar SQL, which in turn will
426 # result in a vocal exception.
427 sub _resolve_aliastypes_from_select_args {
428 my ( $self, $attrs ) = @_;
430 $self->throw_exception ('Unable to analyze custom {from}')
431 if ref $attrs->{from} ne 'ARRAY';
433 # what we will return
436 # see what aliases are there to work with
438 for my $node (@{$attrs->{from}}) {
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 => $j->{-join_path}||[] } if (
447 # not array == {from} head == can't be multiplying
448 ( ref($node) 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 = $self->_resolve_column_info ($attrs->{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 $sql_maker->{name_sep} = '';
484 my ($lquote, $rquote, $sep) = map { quotemeta $_ } ($sql_maker->_quote_chars, $sql_maker->name_sep);
486 # generate sql chunks
489 $sql_maker->_recurse_where ($attrs->{where}),
490 $sql_maker->_parse_rs_attrs ({ having => $attrs->{having} }),
493 $sql_maker->_parse_rs_attrs ({ group_by => $attrs->{group_by} }),
496 $sql_maker->_recurse_from (
497 ref $attrs->{from}[0] eq 'ARRAY' ? $attrs->{from}[0][0] : $attrs->{from}[0],
498 @{$attrs->{from}}[1 .. $#{$attrs->{from}}],
502 $sql_maker->_recurse_fields ($attrs->{select}),
505 map { $_->[0] } $self->_extract_order_criteria ($attrs->{order_by}, $sql_maker),
509 # throw away empty chunks
510 $_ = [ map { $_ || () } @$_ ] for values %$to_scan;
512 # first see if we have any exact matches (qualified or unqualified)
513 for my $type (keys %$to_scan) {
514 for my $piece (@{$to_scan->{$type}}) {
515 if ($colinfo->{$piece} and my $alias = $colinfo->{$piece}{-source_alias}) {
516 $aliases_by_type->{$type}{$alias} ||= { -parents => $alias_list->{$alias}{-join_path}||[] };
517 $aliases_by_type->{$type}{$alias}{-seen_columns}{$colinfo->{$piece}{-fq_colname}} = $piece;
522 # now loop through all fully qualified columns and get the corresponding
523 # alias (should work even if they are in scalarrefs)
524 for my $alias (keys %$alias_list) {
526 $lquote $alias $rquote $sep (?: $lquote ([^$rquote]+) $rquote )?
528 \b $alias \. ([^\s\)\($rquote]+)?
531 for my $type (keys %$to_scan) {
532 for my $piece (@{$to_scan->{$type}}) {
533 if (my @matches = $piece =~ /$al_re/g) {
534 $aliases_by_type->{$type}{$alias} ||= { -parents => $alias_list->{$alias}{-join_path}||[] };
535 $aliases_by_type->{$type}{$alias}{-seen_columns}{"$alias.$_"} = "$alias.$_"
536 for grep { defined $_ } @matches;
542 # now loop through unqualified column names, and try to locate them within
544 for my $col (keys %$colinfo) {
545 next if $col =~ / \. /x; # if column is qualified it was caught by the above
547 my $col_re = qr/ $lquote ($col) $rquote /x;
549 for my $type (keys %$to_scan) {
550 for my $piece (@{$to_scan->{$type}}) {
551 if ( my @matches = $piece =~ /$col_re/g) {
552 my $alias = $colinfo->{$col}{-source_alias};
553 $aliases_by_type->{$type}{$alias} ||= { -parents => $alias_list->{$alias}{-join_path}||[] };
554 $aliases_by_type->{$type}{$alias}{-seen_columns}{"$alias.$_"} = $_
555 for grep { defined $_ } @matches;
561 # Add any non-left joins to the restriction list (such joins are indeed restrictions)
562 for my $j (values %$alias_list) {
563 my $alias = $j->{-alias} or next;
564 $aliases_by_type->{restricting}{$alias} ||= { -parents => $j->{-join_path}||[] } if (
565 (not $j->{-join_type})
567 ($j->{-join_type} !~ /^left (?: \s+ outer)? $/xi)
571 for (keys %$aliases_by_type) {
572 delete $aliases_by_type->{$_} unless keys %{$aliases_by_type->{$_}};
575 return $aliases_by_type;
578 # This is the engine behind { distinct => 1 }
579 sub _group_over_selection {
580 my ($self, $attrs) = @_;
582 my $colinfos = $self->_resolve_column_info ($attrs->{from});
584 my (@group_by, %group_index);
586 # the logic is: if it is a { func => val } we assume an aggregate,
587 # otherwise if \'...' or \[...] we assume the user knows what is
588 # going on thus group over it
589 for (@{$attrs->{select}}) {
590 if (! ref($_) or ref ($_) ne 'HASH' ) {
593 if ($colinfos->{$_} and $_ !~ /\./ ) {
594 # add a fully qualified version as well
595 $group_index{"$colinfos->{$_}{-source_alias}.$_"}++;
600 # add any order_by parts *from the main source* that are not already
601 # present in the group_by
602 # we need to be careful not to add any named functions/aggregates
603 # i.e. order_by => [ ... { count => 'foo' } ... ]
605 for ($self->_extract_order_criteria($attrs->{order_by})) {
606 # only consider real columns (for functions the user got to do an explicit group_by)
616 $colinfos->{$chunk}{-source_alias} ne $attrs->{alias}
622 $chunk = $colinfos->{$chunk}{-fq_colname};
623 push @group_by, $chunk unless $group_index{$chunk}++;
627 ? (\@group_by, (@leftovers ? \@leftovers : undef) )
632 sub _resolve_ident_sources {
633 my ($self, $ident) = @_;
635 my $alias2source = {};
637 # the reason this is so contrived is that $ident may be a {from}
638 # structure, specifying multiple tables to join
639 if ( blessed $ident && $ident->isa("DBIx::Class::ResultSource") ) {
640 # this is compat mode for insert/update/delete which do not deal with aliases
641 $alias2source->{me} = $ident;
643 elsif (ref $ident eq 'ARRAY') {
647 if (ref $_ eq 'HASH') {
650 if (ref $_ eq 'ARRAY' and ref $_->[0] eq 'HASH') {
654 $alias2source->{$tabinfo->{-alias}} = $tabinfo->{-rsrc}
655 if ($tabinfo->{-rsrc});
659 return $alias2source;
662 # Takes $ident, \@column_names
664 # returns { $column_name => \%column_info, ... }
665 # also note: this adds -result_source => $rsrc to the column info
667 # If no columns_names are supplied returns info about *all* columns
669 sub _resolve_column_info {
670 my ($self, $ident, $colnames) = @_;
671 my $alias2src = $self->_resolve_ident_sources($ident);
673 my (%seen_cols, @auto_colnames);
675 # compile a global list of column names, to be able to properly
676 # disambiguate unqualified column names (if at all possible)
677 for my $alias (keys %$alias2src) {
678 my $rsrc = $alias2src->{$alias};
679 for my $colname ($rsrc->columns) {
680 push @{$seen_cols{$colname}}, $alias;
681 push @auto_colnames, "$alias.$colname" unless $colnames;
687 grep { @{$seen_cols{$_}} == 1 } (keys %seen_cols),
690 my (%return, $colinfos);
691 foreach my $col (@$colnames) {
692 my ($source_alias, $colname) = $col =~ m/^ (?: ([^\.]+) \. )? (.+) $/x;
694 # if the column was seen exactly once - we know which rsrc it came from
695 $source_alias ||= $seen_cols{$colname}[0]
696 if ($seen_cols{$colname} and @{$seen_cols{$colname}} == 1);
698 next unless $source_alias;
700 my $rsrc = $alias2src->{$source_alias}
705 ( $colinfos->{$source_alias} ||= $rsrc->columns_info )->{$colname}
707 $self->throw_exception(
708 "No such column '$colname' on source " . $rsrc->source_name
711 -result_source => $rsrc,
712 -source_alias => $source_alias,
713 -fq_colname => $col eq $colname ? "$source_alias.$col" : $col,
714 -colname => $colname,
717 $return{"$source_alias.$colname"} = $return{$col} if $col eq $colname;
723 # The DBIC relationship chaining implementation is pretty simple - every
724 # new related_relationship is pushed onto the {from} stack, and the {select}
725 # window simply slides further in. This means that when we count somewhere
726 # in the middle, we got to make sure that everything in the join chain is an
727 # actual inner join, otherwise the count will come back with unpredictable
728 # results (a resultset may be generated with _some_ rows regardless of if
729 # the relation which the $rs currently selects has rows or not). E.g.
730 # $artist_rs->cds->count - normally generates:
731 # SELECT COUNT( * ) FROM artist me LEFT JOIN cd cds ON cds.artist = me.artistid
732 # which actually returns the number of artists * (number of cds || 1)
734 # So what we do here is crawl {from}, determine if the current alias is at
735 # the top of the stack, and if not - make sure the chain is inner-joined down
738 sub _inner_join_to_node {
739 my ($self, $from, $alias) = @_;
741 # subqueries and other oddness are naturally not supported
747 ref $from->[0] ne 'HASH'
751 $from->[0]{-alias} eq $alias # this last bit means $alias is the head of $from - nothing to do
754 # find the current $alias in the $from structure
757 for my $j (@{$from}[1 .. $#$from]) {
758 if ($j->[0]{-alias} eq $alias) {
759 $switch_branch = $j->[0]{-join_path};
764 # something else went quite wrong
765 return $from unless $switch_branch;
767 # So it looks like we will have to switch some stuff around.
768 # local() is useless here as we will be leaving the scope
769 # anyway, and deep cloning is just too fucking expensive
770 # So replace the first hashref in the node arrayref manually
771 my @new_from = ($from->[0]);
772 my $sw_idx = { map { (values %$_), 1 } @$switch_branch }; #there's one k/v per join-path
774 for my $j (@{$from}[1 .. $#$from]) {
775 my $jalias = $j->[0]{-alias};
777 if ($sw_idx->{$jalias}) {
778 my %attrs = %{$j->[0]};
779 delete $attrs{-join_type};
793 sub _extract_order_criteria {
794 my ($self, $order_by, $sql_maker) = @_;
797 my ($sql_maker, $order_by, $orig_quote_chars) = @_;
799 return scalar $sql_maker->_order_by_chunks ($order_by)
802 my ($lq, $rq, $sep) = map { quotemeta($_) } (
803 ($orig_quote_chars ? @$orig_quote_chars : $sql_maker->_quote_chars),
808 for ($sql_maker->_order_by_chunks ($order_by) ) {
809 my $chunk = ref $_ ? [ @$_ ] : [ $_ ];
810 ($chunk->[0]) = $sql_maker->_split_order_chunk($chunk->[0]);
812 # order criteria may have come back pre-quoted (literals and whatnot)
813 # this is fragile, but the best we can currently do
814 $chunk->[0] =~ s/^ $lq (.+?) $rq $sep $lq (.+?) $rq $/"$1.$2"/xe
815 or $chunk->[0] =~ s/^ $lq (.+) $rq $/$1/x;
817 push @chunks, $chunk;
824 return $parser->($sql_maker, $order_by);
827 $sql_maker = $self->sql_maker;
829 # pass these in to deal with literals coming from
830 # the user or the deep guts of prefetch
831 my $orig_quote_chars = [$sql_maker->_quote_chars];
833 local $sql_maker->{quote_char};
834 return $parser->($sql_maker, $order_by, $orig_quote_chars);
838 sub _order_by_is_stable {
839 my ($self, $ident, $order_by, $where) = @_;
841 my $colinfo = $self->_resolve_column_info($ident, [
842 (map { $_->[0] } $self->_extract_order_criteria($order_by)),
843 $where ? @{$self->_extract_fixed_condition_columns($where)} :(),
846 return undef unless keys %$colinfo;
849 $cols_per_src->{$_->{-source_alias}}{$_->{-colname}} = $_ for values %$colinfo;
851 for (values %$cols_per_src) {
852 my $src = (values %$_)[0]->{-result_source};
853 return 1 if $src->_identifying_column_set($_);
859 # this is almost identical to the above, except it accepts only
860 # a single rsrc, and will succeed only if the first portion of the order
862 # returns that portion as a colinfo hashref on success
863 sub _main_source_order_by_portion_is_stable {
864 my ($self, $main_rsrc, $order_by, $where) = @_;
866 die "Huh... I expect a blessed result_source..."
867 if ref($main_rsrc) eq 'ARRAY';
871 ( $self->_extract_order_criteria($order_by) )
873 return unless @ord_cols;
875 my $colinfos = $self->_resolve_column_info($main_rsrc);
877 for (0 .. $#ord_cols) {
879 ! $colinfos->{$ord_cols[$_]}
881 $colinfos->{$ord_cols[$_]}{-result_source} != $main_rsrc
888 # we just truncated it above
889 return unless @ord_cols;
891 my $order_portion_ci = { map {
892 $colinfos->{$_}{-colname} => $colinfos->{$_},
893 $colinfos->{$_}{-fq_colname} => $colinfos->{$_},
896 # since all we check here are the start of the order_by belonging to the
897 # top level $rsrc, a present identifying set will mean that the resultset
898 # is ordered by its leftmost table in a stable manner
900 # RV of _identifying_column_set contains unqualified names only
901 my $unqualified_idset = $main_rsrc->_identifying_column_set({
903 $self->_resolve_column_info(
904 $main_rsrc, $self->_extract_fixed_condition_columns($where)
911 my %unqualified_idcols_from_order = map {
912 $order_portion_ci->{$_} ? ( $_ => $order_portion_ci->{$_} ) : ()
913 } @$unqualified_idset;
915 # extra optimization - cut the order_by at the end of the identifying set
916 # (just in case the user was stupid and overlooked the obvious)
917 for my $i (0 .. $#ord_cols) {
918 my $col = $ord_cols[$i];
919 my $unqualified_colname = $order_portion_ci->{$col}{-colname};
920 $ret_info->{$col} = { %{$order_portion_ci->{$col}}, -idx_in_order_subset => $i };
921 delete $unqualified_idcols_from_order{$ret_info->{$col}{-colname}};
923 # we didn't reach the end of the identifying portion yet
924 return $ret_info unless keys %unqualified_idcols_from_order;
927 die 'How did we get here...';
930 # returns an arrayref of column names which *definitely* have some
931 # sort of non-nullable equality requested in the given condition
932 # specification. This is used to figure out if a resultset is
933 # constrained to a column which is part of a unique constraint,
934 # which in turn allows us to better predict how ordering will behave
937 # this is a rudimentary, incomplete, and error-prone extractor
938 # however this is OK - it is conservative, and if we can not find
939 # something that is in fact there - the stack will recover gracefully
940 # Also - DQ and the mst it rode in on will save us all RSN!!!
941 sub _extract_fixed_condition_columns {
942 my ($self, $where) = @_;
944 return unless ref $where eq 'HASH';
947 for my $lhs (keys %$where) {
948 if ($lhs =~ /^\-and$/i) {
949 push @cols, ref $where->{$lhs} eq 'ARRAY'
950 ? ( map { @{ $self->_extract_fixed_condition_columns($_) } } @{$where->{$lhs}} )
951 : @{ $self->_extract_fixed_condition_columns($where->{$lhs}) }
954 elsif ($lhs !~ /^\-/) {
955 my $val = $where->{$lhs};
957 push @cols, $lhs if (defined $val and (
960 (ref $val eq 'HASH' and keys %$val == 1 and defined $val->{'='})