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(@_);
37 my $orig_joins = delete $aliastypes->{joining};
38 my $orig_multiplying = $aliastypes->{multiplying};
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 (! defined $j->[0]{-alias}) # legacy crap
61 $need_joins{$j->[0]{-alias}}
66 multiplying => { map { $need_joins{$_} ? ($_ => $orig_multiplying->{$_}) : () } keys %$orig_multiplying },
68 joining => { map { $_ => $orig_joins->{$_} } keys %need_joins },
73 # This is the code producing joined subqueries like:
74 # SELECT me.*, other.* FROM ( SELECT me.* FROM ... ) JOIN other ON ...
76 sub _adjust_select_args_for_complex_prefetch {
77 my ($self, $from, $select, $where, $attrs) = @_;
79 $self->throw_exception ('Complex prefetches are not supported on resultsets with a custom from attribute')
80 if (ref $from ne 'ARRAY' || ref $from->[0] ne 'HASH' || ref $from->[1] ne 'ARRAY');
82 my $root_alias = $attrs->{alias};
84 # generate inner/outer attribute lists, remove stuff that doesn't apply
85 my $outer_attrs = { %$attrs };
86 delete @{$outer_attrs}{qw(where bind rows offset group_by _grouped_by_distinct having)};
88 my $inner_attrs = { %$attrs };
89 delete @{$inner_attrs}{qw(from for collapse select as _related_results_construction)};
91 # there is no point of ordering the insides if there is no limit
92 delete $inner_attrs->{order_by} if (
93 delete $inner_attrs->{_order_is_artificial}
95 ! $inner_attrs->{rows}
98 # generate the inner/outer select lists
99 # for inside we consider only stuff *not* brought in by the prefetch
100 # on the outside we substitute any function for its alias
101 my $outer_select = [ @$select ];
104 my ($root_node, $root_node_offset);
106 for my $i (0 .. $#$from) {
107 my $node = $from->[$i];
108 my $h = (ref $node eq 'HASH') ? $node
109 : (ref $node eq 'ARRAY' and ref $node->[0] eq 'HASH') ? $node->[0]
113 if ( ($h->{-alias}||'') eq $root_alias and $h->{-rsrc} ) {
115 $root_node_offset = $i;
120 $self->throw_exception ('Complex prefetches are not supported on resultsets with a custom from attribute')
123 # use the heavy duty resolver to take care of aliased/nonaliased naming
124 my $colinfo = $self->_resolve_column_info($from);
125 my $selected_root_columns;
127 for my $i (0 .. $#$outer_select) {
128 my $sel = $outer_select->[$i];
131 $colinfo->{$sel} and $colinfo->{$sel}{-source_alias} ne $root_alias
134 if (ref $sel eq 'HASH' ) {
135 $sel->{-as} ||= $attrs->{as}[$i];
136 $outer_select->[$i] = join ('.', $root_alias, ($sel->{-as} || "inner_column_$i") );
138 elsif (! ref $sel and my $ci = $colinfo->{$sel}) {
139 $selected_root_columns->{$ci->{-colname}} = 1;
142 push @$inner_select, $sel;
144 push @{$inner_attrs->{as}}, $attrs->{as}[$i];
147 # We will need to fetch all native columns in the inner subquery, which may
148 # be a part of an *outer* join condition, or an order_by (which needs to be
150 # We can not just fetch everything because a potential has_many restricting
151 # join collapse *will not work* on heavy data types.
152 my $connecting_aliastypes = $self->_resolve_aliastypes_from_select_args(
159 for (sort map { keys %{$_->{-seen_columns}||{}} } map { values %$_ } values %$connecting_aliastypes) {
160 my $ci = $colinfo->{$_} or next;
162 $ci->{-source_alias} eq $root_alias
164 ! $selected_root_columns->{$ci->{-colname}}++
166 # adding it to both to keep limits not supporting dark selectors happy
167 push @$inner_select, $ci->{-fq_colname};
168 push @{$inner_attrs->{as}}, $ci->{-fq_colname};
172 # construct the inner $from and lock it in a subquery
173 # we need to prune first, because this will determine if we need a group_by below
174 # throw away all non-selecting, non-restricting multijoins
175 # (since we def. do not care about multiplication those inside the subquery)
176 my $inner_subq = do {
178 # must use it here regardless of user requests
179 local $self->{_use_join_optimizer} = 1;
181 # throw away multijoins since we def. do not care about those inside the subquery
182 my ($inner_from, $inner_aliastypes) = $self->_prune_unused_joins ($from, $inner_select, $where, {
183 %$inner_attrs, _force_prune_multiplying_joins => 1
186 # uh-oh a multiplier (which is not us) left in, this is a problem
188 $inner_aliastypes->{multiplying}
190 # if there are user-supplied groups - assume user knows wtf they are up to
191 ( ! $inner_aliastypes->{grouping} or $inner_attrs->{_grouped_by_distinct} )
193 my @multipliers = grep { $_ ne $root_alias } keys %{$inner_aliastypes->{multiplying}}
196 # if none of the multipliers came from an order_by (guaranteed to have been combined
197 # with a limit) - easy - just slap a group_by to simulate a collape and be on our way
199 ! $inner_aliastypes->{ordering}
201 ! first { $inner_aliastypes->{ordering}{$_} } @multipliers
204 my $unprocessed_order_chunks;
205 ($inner_attrs->{group_by}, $unprocessed_order_chunks) = $self->_group_over_selection ({
208 select => $inner_select,
211 $self->throw_exception (
212 'A required group_by clause could not be constructed automatically due to a complex '
213 . 'order_by criteria. Either order_by columns only (no functions) or construct a suitable '
215 ) if $unprocessed_order_chunks;
218 # We need to order by external columns and group at the same time
219 # so we can calculate the proper limit
220 # This doesn't really make sense in SQL, however from DBICs point
221 # of view is rather valid (order the leftmost objects by whatever
222 # criteria and get the offset/rows many). There is a way around
223 # this however in SQL - we simply tae the direction of each piece
224 # of the foreign order and convert them to MIN(X) for ASC or MAX(X)
225 # for DESC, and group_by the root columns. The end result should be
226 # exactly what we expect
228 # supplement the main selection with pks if not already there,
229 # as they will have to be a part of the group_by to colapse
231 my $cur_sel = { map { $_ => 1 } @$inner_select };
233 my @pks = map { "$root_alias.$_" } $root_node->{-rsrc}->primary_columns
234 or $self->throw_exception( sprintf
235 'Unable to perform complex limited prefetch off %s without declared primary key',
236 $root_node->{-rsrc}->source_name,
239 push @$inner_select, $col
240 unless $cur_sel->{$col}++;
243 # wrap any part of the order_by that "responds" to an ordering alias
245 # FIXME - this code is a joke, will need to be completely rewritten in
246 # the DQ branch. But I need to push a POC here, otherwise the
247 # pesky tests won't pass
248 my $sql_maker = $self->sql_maker;
249 my ($lquote, $rquote, $sep) = map { quotemeta $_ } ($sql_maker->_quote_chars, $sql_maker->name_sep);
250 my $own_re = qr/ $lquote \Q$root_alias\E $rquote $sep | \b \Q$root_alias\E $sep /x;
251 my @order_chunks = map { ref $_ eq 'ARRAY' ? $_ : [ $_ ] } $sql_maker->_order_by_chunks($attrs->{order_by});
252 my @new_order = map { \$_ } @order_chunks;
253 my $inner_columns_info = $self->_resolve_column_info($inner_from);
255 # loop through and replace stuff that is not "ours" with a min/max func
256 # everything is a literal at this point, since we are likely properly
258 for my $i (0 .. $#new_order) {
259 my $chunk = $order_chunks[$i][0];
262 next if $chunk =~ $own_re;
264 ($chunk, my $is_desc) = $sql_maker->_split_order_chunk($chunk);
266 # maybe our own unqualified column
268 $lquote and $sep and $chunk =~ /^ $lquote ([^$sep]+) $rquote $/x
274 $inner_columns_info->{$ord_bit}
276 $inner_columns_info->{$ord_bit}{-source_alias} eq $root_alias
282 ($is_desc ? 'MAX' : 'MIN'),
284 ($is_desc ? ' DESC' : ''),
286 @ {$order_chunks[$i]} [ 1 .. $#{$order_chunks[$i]} ]
290 $inner_attrs->{order_by} = \@new_order;
292 # do not care about leftovers here - it will be all the functions
294 ($inner_attrs->{group_by}) = $self->_group_over_selection ({
297 select => $inner_select,
302 # we already optimized $inner_from above
303 # and already local()ized
304 $self->{_use_join_optimizer} = 0;
306 # generate the subquery
307 $self->_select_args_to_query (
315 # Generate the outer from - this is relatively easy (really just replace
316 # the join slot with the subquery), with a major caveat - we can not
317 # join anything that is non-selecting (not part of the prefetch), but at
318 # the same time is a multi-type relationship, as it will explode the result.
320 # There are two possibilities here
321 # - either the join is non-restricting, in which case we simply throw it away
322 # - it is part of the restrictions, in which case we need to collapse the outer
323 # result by tackling yet another group_by to the outside of the query
325 # work on a shallow copy
330 # we may not be the head
331 if ($root_node_offset) {
332 # first generate the outer_from, up and including the substitution point
333 @outer_from = splice @$from, 0, $root_node_offset;
337 -alias => $root_alias,
338 -rsrc => $root_node->{-rsrc},
339 $root_alias => $inner_subq,
341 @{$from->[0]}[1 .. $#{$from->[0]}],
346 -alias => $root_alias,
347 -rsrc => $root_node->{-rsrc},
348 $root_alias => $inner_subq,
352 shift @$from; # what we just replaced above
354 # scan the *remaining* from spec against different attributes, and see which joins are needed
356 my $outer_aliastypes =
357 $self->_resolve_aliastypes_from_select_args( $from, $outer_select, $where, $outer_attrs );
360 my ($outer_select_chain, @outer_nonselecting_chains) = map { +{
361 map { $_ => 1 } map { values %$_} map { @{$_->{-parents}} } values %{ $outer_aliastypes->{$_} || {} }
362 } } qw/selecting restricting grouping ordering/;
364 # see what's left - throw away if not selecting/restricting
365 # also throw in a group_by if a non-selecting multiplier,
366 # to guard against cross-join explosions
367 my $need_outer_group_by;
368 while (my $j = shift @$from) {
369 my $alias = $j->[0]{-alias};
372 $outer_select_chain->{$alias}
376 elsif (first { $_->{$alias} } @outer_nonselecting_chains ) {
377 push @outer_from, $j;
378 $need_outer_group_by ||= $outer_aliastypes->{multiplying}{$alias} ? 1 : 0;
382 if ( $need_outer_group_by and $attrs->{_grouped_by_distinct} ) {
383 my $unprocessed_order_chunks;
384 ($outer_attrs->{group_by}, $unprocessed_order_chunks) = $self->_group_over_selection ({
386 from => \@outer_from,
387 select => $outer_select,
390 $self->throw_exception (
391 'A required group_by clause could not be constructed automatically due to a complex '
392 . 'order_by criteria. Either order_by columns only (no functions) or construct a suitable '
394 ) if $unprocessed_order_chunks;
398 # This is totally horrific - the $where ends up in both the inner and outer query
399 # Unfortunately not much can be done until SQLA2 introspection arrives, and even
400 # then if where conditions apply to the *right* side of the prefetch, you may have
401 # to both filter the inner select (e.g. to apply a limit) and then have to re-filter
402 # the outer select to exclude joins you didin't want in the first place
404 # OTOH it can be seen as a plus: <ash> (notes that this query would make a DBA cry ;)
405 return (\@outer_from, $outer_select, $where, $outer_attrs);
409 # I KNOW THIS SUCKS! GET SQLA2 OUT THE DOOR SO THIS CAN DIE!
411 # Due to a lack of SQLA2 we fall back to crude scans of all the
412 # select/where/order/group attributes, in order to determine what
413 # aliases are neded to fulfill the query. This information is used
414 # throughout the code to prune unnecessary JOINs from the queries
415 # in an attempt to reduce the execution time.
416 # Although the method is pretty horrific, the worst thing that can
417 # happen is for it to fail due to some scalar SQL, which in turn will
418 # result in a vocal exception.
419 sub _resolve_aliastypes_from_select_args {
420 my ( $self, $from, $select, $where, $attrs ) = @_;
422 $self->throw_exception ('Unable to analyze custom {from}')
423 if ref $from ne 'ARRAY';
425 # what we will return
428 # see what aliases are there to work with
432 $j = $j->[0] if ref $j eq 'ARRAY';
433 my $al = $j->{-alias}
436 $alias_list->{$al} = $j;
437 $aliases_by_type->{multiplying}{$al} ||= { -parents => $j->{-join_path}||[] } if (
438 # not array == {from} head == can't be multiplying
439 ( ref($_) eq 'ARRAY' and ! $j->{-is_single} )
441 # a parent of ours is already a multiplier
442 ( grep { $aliases_by_type->{multiplying}{$_} } @{ $j->{-join_path}||[] } )
446 # get a column to source/alias map (including unambiguous unqualified ones)
447 my $colinfo = $self->_resolve_column_info ($from);
449 # set up a botched SQLA
450 my $sql_maker = $self->sql_maker;
452 # these are throw away results, do not pollute the bind stack
453 local $sql_maker->{select_bind};
454 local $sql_maker->{where_bind};
455 local $sql_maker->{group_bind};
456 local $sql_maker->{having_bind};
457 local $sql_maker->{from_bind};
459 # we can't scan properly without any quoting (\b doesn't cut it
460 # everywhere), so unless there is proper quoting set - use our
461 # own weird impossible character.
462 # Also in the case of no quoting, we need to explicitly disable
463 # name_sep, otherwise sorry nasty legacy syntax like
464 # { 'count(foo.id)' => { '>' => 3 } } will stop working >:(
465 local $sql_maker->{quote_char} = $sql_maker->{quote_char};
466 local $sql_maker->{name_sep} = $sql_maker->{name_sep};
468 unless (defined $sql_maker->{quote_char} and length $sql_maker->{quote_char}) {
469 $sql_maker->{quote_char} = ["\x00", "\xFF"];
470 # if we don't unset it we screw up retarded but unfortunately working
471 # 'MAX(foo.bar)' => { '>', 3 }
472 $sql_maker->{name_sep} = '';
475 my ($lquote, $rquote, $sep) = map { quotemeta $_ } ($sql_maker->_quote_chars, $sql_maker->name_sep);
477 # generate sql chunks
480 $sql_maker->_recurse_where ($where),
481 $sql_maker->_parse_rs_attrs ({ having => $attrs->{having} }),
484 $sql_maker->_parse_rs_attrs ({ group_by => $attrs->{group_by} }),
487 $sql_maker->_recurse_from (
488 ref $from->[0] eq 'ARRAY' ? $from->[0][0] : $from->[0],
489 @{$from}[1 .. $#$from],
493 $sql_maker->_recurse_fields ($select),
496 map { $_->[0] } $self->_extract_order_criteria ($attrs->{order_by}, $sql_maker),
500 # throw away empty chunks
501 $_ = [ map { $_ || () } @$_ ] for values %$to_scan;
503 # first see if we have any exact matches (qualified or unqualified)
504 for my $type (keys %$to_scan) {
505 for my $piece (@{$to_scan->{$type}}) {
506 if ($colinfo->{$piece} and my $alias = $colinfo->{$piece}{-source_alias}) {
507 $aliases_by_type->{$type}{$alias} ||= { -parents => $alias_list->{$alias}{-join_path}||[] };
508 $aliases_by_type->{$type}{$alias}{-seen_columns}{$colinfo->{$piece}{-fq_colname}} = $piece;
513 # now loop through all fully qualified columns and get the corresponding
514 # alias (should work even if they are in scalarrefs)
515 for my $alias (keys %$alias_list) {
517 $lquote $alias $rquote $sep (?: $lquote ([^$rquote]+) $rquote )?
519 \b $alias \. ([^\s\)\($rquote]+)?
522 for my $type (keys %$to_scan) {
523 for my $piece (@{$to_scan->{$type}}) {
524 if (my @matches = $piece =~ /$al_re/g) {
525 $aliases_by_type->{$type}{$alias} ||= { -parents => $alias_list->{$alias}{-join_path}||[] };
526 $aliases_by_type->{$type}{$alias}{-seen_columns}{"$alias.$_"} = "$alias.$_"
527 for grep { defined $_ } @matches;
533 # now loop through unqualified column names, and try to locate them within
535 for my $col (keys %$colinfo) {
536 next if $col =~ / \. /x; # if column is qualified it was caught by the above
538 my $col_re = qr/ $lquote ($col) $rquote /x;
540 for my $type (keys %$to_scan) {
541 for my $piece (@{$to_scan->{$type}}) {
542 if ( my @matches = $piece =~ /$col_re/g) {
543 my $alias = $colinfo->{$col}{-source_alias};
544 $aliases_by_type->{$type}{$alias} ||= { -parents => $alias_list->{$alias}{-join_path}||[] };
545 $aliases_by_type->{$type}{$alias}{-seen_columns}{"$alias.$_"} = $_
546 for grep { defined $_ } @matches;
552 # Add any non-left joins to the restriction list (such joins are indeed restrictions)
553 for my $j (values %$alias_list) {
554 my $alias = $j->{-alias} or next;
555 $aliases_by_type->{restricting}{$alias} ||= { -parents => $j->{-join_path}||[] } if (
556 (not $j->{-join_type})
558 ($j->{-join_type} !~ /^left (?: \s+ outer)? $/xi)
562 for (keys %$aliases_by_type) {
563 delete $aliases_by_type->{$_} unless keys %{$aliases_by_type->{$_}};
566 return $aliases_by_type;
569 # This is the engine behind { distinct => 1 }
570 sub _group_over_selection {
571 my ($self, $attrs) = @_;
573 my $colinfos = $self->_resolve_column_info ($attrs->{from});
575 my (@group_by, %group_index);
577 # the logic is: if it is a { func => val } we assume an aggregate,
578 # otherwise if \'...' or \[...] we assume the user knows what is
579 # going on thus group over it
580 for (@{$attrs->{select}}) {
581 if (! ref($_) or ref ($_) ne 'HASH' ) {
584 if ($colinfos->{$_} and $_ !~ /\./ ) {
585 # add a fully qualified version as well
586 $group_index{"$colinfos->{$_}{-source_alias}.$_"}++;
591 # add any order_by parts *from the main source* that are not already
592 # present in the group_by
593 # we need to be careful not to add any named functions/aggregates
594 # i.e. order_by => [ ... { count => 'foo' } ... ]
596 for ($self->_extract_order_criteria($attrs->{order_by})) {
597 # only consider real columns (for functions the user got to do an explicit group_by)
607 $colinfos->{$chunk}{-source_alias} ne $attrs->{alias}
613 $chunk = $colinfos->{$chunk}{-fq_colname};
614 push @group_by, $chunk unless $group_index{$chunk}++;
618 ? (\@group_by, (@leftovers ? \@leftovers : undef) )
623 sub _resolve_ident_sources {
624 my ($self, $ident) = @_;
626 my $alias2source = {};
628 # the reason this is so contrived is that $ident may be a {from}
629 # structure, specifying multiple tables to join
630 if ( blessed $ident && $ident->isa("DBIx::Class::ResultSource") ) {
631 # this is compat mode for insert/update/delete which do not deal with aliases
632 $alias2source->{me} = $ident;
634 elsif (ref $ident eq 'ARRAY') {
638 if (ref $_ eq 'HASH') {
641 if (ref $_ eq 'ARRAY' and ref $_->[0] eq 'HASH') {
645 $alias2source->{$tabinfo->{-alias}} = $tabinfo->{-rsrc}
646 if ($tabinfo->{-rsrc});
650 return $alias2source;
653 # Takes $ident, \@column_names
655 # returns { $column_name => \%column_info, ... }
656 # also note: this adds -result_source => $rsrc to the column info
658 # If no columns_names are supplied returns info about *all* columns
660 sub _resolve_column_info {
661 my ($self, $ident, $colnames) = @_;
662 my $alias2src = $self->_resolve_ident_sources($ident);
664 my (%seen_cols, @auto_colnames);
666 # compile a global list of column names, to be able to properly
667 # disambiguate unqualified column names (if at all possible)
668 for my $alias (keys %$alias2src) {
669 my $rsrc = $alias2src->{$alias};
670 for my $colname ($rsrc->columns) {
671 push @{$seen_cols{$colname}}, $alias;
672 push @auto_colnames, "$alias.$colname" unless $colnames;
678 grep { @{$seen_cols{$_}} == 1 } (keys %seen_cols),
681 my (%return, $colinfos);
682 foreach my $col (@$colnames) {
683 my ($source_alias, $colname) = $col =~ m/^ (?: ([^\.]+) \. )? (.+) $/x;
685 # if the column was seen exactly once - we know which rsrc it came from
686 $source_alias ||= $seen_cols{$colname}[0]
687 if ($seen_cols{$colname} and @{$seen_cols{$colname}} == 1);
689 next unless $source_alias;
691 my $rsrc = $alias2src->{$source_alias}
696 ( $colinfos->{$source_alias} ||= $rsrc->columns_info )->{$colname}
698 $self->throw_exception(
699 "No such column '$colname' on source " . $rsrc->source_name
702 -result_source => $rsrc,
703 -source_alias => $source_alias,
704 -fq_colname => $col eq $colname ? "$source_alias.$col" : $col,
705 -colname => $colname,
708 $return{"$source_alias.$colname"} = $return{$col} if $col eq $colname;
714 # The DBIC relationship chaining implementation is pretty simple - every
715 # new related_relationship is pushed onto the {from} stack, and the {select}
716 # window simply slides further in. This means that when we count somewhere
717 # in the middle, we got to make sure that everything in the join chain is an
718 # actual inner join, otherwise the count will come back with unpredictable
719 # results (a resultset may be generated with _some_ rows regardless of if
720 # the relation which the $rs currently selects has rows or not). E.g.
721 # $artist_rs->cds->count - normally generates:
722 # SELECT COUNT( * ) FROM artist me LEFT JOIN cd cds ON cds.artist = me.artistid
723 # which actually returns the number of artists * (number of cds || 1)
725 # So what we do here is crawl {from}, determine if the current alias is at
726 # the top of the stack, and if not - make sure the chain is inner-joined down
729 sub _inner_join_to_node {
730 my ($self, $from, $alias) = @_;
732 # subqueries and other oddness are naturally not supported
738 ref $from->[0] ne 'HASH'
742 $from->[0]{-alias} eq $alias # this last bit means $alias is the head of $from - nothing to do
745 # find the current $alias in the $from structure
748 for my $j (@{$from}[1 .. $#$from]) {
749 if ($j->[0]{-alias} eq $alias) {
750 $switch_branch = $j->[0]{-join_path};
755 # something else went quite wrong
756 return $from unless $switch_branch;
758 # So it looks like we will have to switch some stuff around.
759 # local() is useless here as we will be leaving the scope
760 # anyway, and deep cloning is just too fucking expensive
761 # So replace the first hashref in the node arrayref manually
762 my @new_from = ($from->[0]);
763 my $sw_idx = { map { (values %$_), 1 } @$switch_branch }; #there's one k/v per join-path
765 for my $j (@{$from}[1 .. $#$from]) {
766 my $jalias = $j->[0]{-alias};
768 if ($sw_idx->{$jalias}) {
769 my %attrs = %{$j->[0]};
770 delete $attrs{-join_type};
784 sub _extract_order_criteria {
785 my ($self, $order_by, $sql_maker) = @_;
788 my ($sql_maker, $order_by, $orig_quote_chars) = @_;
790 return scalar $sql_maker->_order_by_chunks ($order_by)
793 my ($lq, $rq, $sep) = map { quotemeta($_) } (
794 ($orig_quote_chars ? @$orig_quote_chars : $sql_maker->_quote_chars),
799 for ($sql_maker->_order_by_chunks ($order_by) ) {
800 my $chunk = ref $_ ? [ @$_ ] : [ $_ ];
801 ($chunk->[0]) = $sql_maker->_split_order_chunk($chunk->[0]);
803 # order criteria may have come back pre-quoted (literals and whatnot)
804 # this is fragile, but the best we can currently do
805 $chunk->[0] =~ s/^ $lq (.+?) $rq $sep $lq (.+?) $rq $/"$1.$2"/xe
806 or $chunk->[0] =~ s/^ $lq (.+) $rq $/$1/x;
808 push @chunks, $chunk;
815 return $parser->($sql_maker, $order_by);
818 $sql_maker = $self->sql_maker;
820 # pass these in to deal with literals coming from
821 # the user or the deep guts of prefetch
822 my $orig_quote_chars = [$sql_maker->_quote_chars];
824 local $sql_maker->{quote_char};
825 return $parser->($sql_maker, $order_by, $orig_quote_chars);
829 sub _order_by_is_stable {
830 my ($self, $ident, $order_by, $where) = @_;
832 my $colinfo = $self->_resolve_column_info($ident, [
833 (map { $_->[0] } $self->_extract_order_criteria($order_by)),
834 $where ? @{$self->_extract_fixed_condition_columns($where)} :(),
837 return undef unless keys %$colinfo;
840 $cols_per_src->{$_->{-source_alias}}{$_->{-colname}} = $_ for values %$colinfo;
842 for (values %$cols_per_src) {
843 my $src = (values %$_)[0]->{-result_source};
844 return 1 if $src->_identifying_column_set($_);
850 # this is almost identical to the above, except it accepts only
851 # a single rsrc, and will succeed only if the first portion of the order
853 # returns that portion as a colinfo hashref on success
854 sub _main_source_order_by_portion_is_stable {
855 my ($self, $main_rsrc, $order_by, $where) = @_;
857 die "Huh... I expect a blessed result_source..."
858 if ref($main_rsrc) eq 'ARRAY';
862 ( $self->_extract_order_criteria($order_by) )
864 return unless @ord_cols;
866 my $colinfos = $self->_resolve_column_info($main_rsrc);
868 for (0 .. $#ord_cols) {
870 ! $colinfos->{$ord_cols[$_]}
872 $colinfos->{$ord_cols[$_]}{-result_source} != $main_rsrc
879 # we just truncated it above
880 return unless @ord_cols;
882 my $order_portion_ci = { map {
883 $colinfos->{$_}{-colname} => $colinfos->{$_},
884 $colinfos->{$_}{-fq_colname} => $colinfos->{$_},
887 # since all we check here are the start of the order_by belonging to the
888 # top level $rsrc, a present identifying set will mean that the resultset
889 # is ordered by its leftmost table in a stable manner
891 # RV of _identifying_column_set contains unqualified names only
892 my $unqualified_idset = $main_rsrc->_identifying_column_set({
894 $self->_resolve_column_info(
895 $main_rsrc, $self->_extract_fixed_condition_columns($where)
902 my %unqualified_idcols_from_order = map {
903 $order_portion_ci->{$_} ? ( $_ => $order_portion_ci->{$_} ) : ()
904 } @$unqualified_idset;
906 # extra optimization - cut the order_by at the end of the identifying set
907 # (just in case the user was stupid and overlooked the obvious)
908 for my $i (0 .. $#ord_cols) {
909 my $col = $ord_cols[$i];
910 my $unqualified_colname = $order_portion_ci->{$col}{-colname};
911 $ret_info->{$col} = { %{$order_portion_ci->{$col}}, -idx_in_order_subset => $i };
912 delete $unqualified_idcols_from_order{$ret_info->{$col}{-colname}};
914 # we didn't reach the end of the identifying portion yet
915 return $ret_info unless keys %unqualified_idcols_from_order;
918 die 'How did we get here...';
921 # returns an arrayref of column names which *definitely* have som
922 # sort of non-nullable equality requested in the given condition
923 # specification. This is used to figure out if a resultset is
924 # constrained to a column which is part of a unique constraint,
925 # which in turn allows us to better predict how ordering will behave
928 # this is a rudimentary, incomplete, and error-prone extractor
929 # however this is OK - it is conservative, and if we can not find
930 # something that is in fact there - the stack will recover gracefully
931 # Also - DQ and the mst it rode in on will save us all RSN!!!
932 sub _extract_fixed_condition_columns {
933 my ($self, $where, $nested) = @_;
935 return unless ref $where eq 'HASH';
938 for my $lhs (keys %$where) {
939 if ($lhs =~ /^\-and$/i) {
940 push @cols, ref $where->{$lhs} eq 'ARRAY'
941 ? ( map { $self->_extract_fixed_condition_columns($_, 1) } @{$where->{$lhs}} )
942 : $self->_extract_fixed_condition_columns($where->{$lhs}, 1)
945 elsif ($lhs !~ /^\-/) {
946 my $val = $where->{$lhs};
948 push @cols, $lhs if (defined $val and (
951 (ref $val eq 'HASH' and keys %$val == 1 and defined $val->{'='})
955 return $nested ? @cols : \@cols;