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package DBIx::Class::SQLMaker::LimitDialects;
use warnings;
use strict;
use List::Util 'first';
use namespace::clean;
# constants are used not only here, but also in comparison tests
sub __rows_bindtype () {
+{ sqlt_datatype => 'integer' }
}
sub __offset_bindtype () {
+{ sqlt_datatype => 'integer' }
}
sub __total_bindtype () {
+{ sqlt_datatype => 'integer' }
}
=head1 NAME
DBIx::Class::SQLMaker::LimitDialects - SQL::Abstract::Limit-like functionality for DBIx::Class::SQLMaker
=head1 DESCRIPTION
This module replicates a lot of the functionality originally found in
L<SQL::Abstract::Limit>. While simple limits would work as-is, the more
complex dialects that require e.g. subqueries could not be reliably
implemented without taking full advantage of the metadata locked within
L<DBIx::Class::ResultSource> classes. After reimplementation of close to
80% of the L<SQL::Abstract::Limit> functionality it was deemed more
practical to simply make an independent DBIx::Class-specific limit-dialect
provider.
=head1 SQL LIMIT DIALECTS
Note that the actual implementations listed below never use C<*> literally.
Instead proper re-aliasing of selectors and order criteria is done, so that
the limit dialect are safe to use on joined resultsets with clashing column
names.
Currently the provided dialects are:
=head2 LimitOffset
SELECT ... LIMIT $limit OFFSET $offset
Supported by B<PostgreSQL> and B<SQLite>
=cut
sub _LimitOffset {
my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_;
$sql .= $self->_parse_rs_attrs( $rs_attrs ) . " LIMIT ?";
push @{$self->{limit_bind}}, [ $self->__rows_bindtype => $rows ];
if ($offset) {
$sql .= " OFFSET ?";
push @{$self->{limit_bind}}, [ $self->__offset_bindtype => $offset ];
}
return $sql;
}
=head2 LimitXY
SELECT ... LIMIT $offset $limit
Supported by B<MySQL> and any L<SQL::Statement> based DBD
=cut
sub _LimitXY {
my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_;
$sql .= $self->_parse_rs_attrs( $rs_attrs ) . " LIMIT ";
if ($offset) {
$sql .= '?, ';
push @{$self->{limit_bind}}, [ $self->__offset_bindtype => $offset ];
}
$sql .= '?';
push @{$self->{limit_bind}}, [ $self->__rows_bindtype => $rows ];
return $sql;
}
=head2 RowNumberOver
SELECT * FROM (
SELECT *, ROW_NUMBER() OVER( ORDER BY ... ) AS RNO__ROW__INDEX FROM (
SELECT ...
)
) WHERE RNO__ROW__INDEX BETWEEN ($offset+1) AND ($limit+$offset)
ANSI standard Limit/Offset implementation. Supported by B<DB2> and
B<< MSSQL >= 2005 >>.
=cut
sub _RowNumberOver {
my ($self, $sql, $rs_attrs, $rows, $offset ) = @_;
# get selectors, and scan the order_by (if any)
my $sq_attrs = $self->_subqueried_limit_attrs ( $sql, $rs_attrs );
# make up an order if none exists
my $requested_order = (delete $rs_attrs->{order_by}) || $self->_rno_default_order;
# the order binds (if any) will need to go at the end of the entire inner select
local $self->{order_bind};
my $rno_ord = $self->_order_by ($requested_order);
push @{$self->{select_bind}}, @{$self->{order_bind}};
# this is the order supplement magic
my $mid_sel = $sq_attrs->{selection_outer};
if (my $extra_order_sel = $sq_attrs->{order_supplement}) {
for my $extra_col (sort
{ $extra_order_sel->{$a} cmp $extra_order_sel->{$b} }
keys %$extra_order_sel
) {
$sq_attrs->{selection_inner} .= sprintf (', %s AS %s',
$extra_col,
$extra_order_sel->{$extra_col},
);
}
}
# and this is order re-alias magic
for my $map ($sq_attrs->{order_supplement}, $sq_attrs->{outer_renames}) {
for my $col (sort { (length $b) <=> (length $a) } keys %{$map||{}} ) {
my $re_col = quotemeta ($col);
$rno_ord =~ s/$re_col/$map->{$col}/;
}
}
# whatever is left of the order_by (only where is processed at this point)
my $group_having = $self->_parse_rs_attrs($rs_attrs);
my $qalias = $self->_quote ($rs_attrs->{alias});
my $idx_name = $self->_quote ('rno__row__index');
push @{$self->{limit_bind}}, [ $self->__offset_bindtype => $offset + 1], [ $self->__total_bindtype => $offset + $rows ];
return <<EOS;
SELECT $sq_attrs->{selection_outer} FROM (
SELECT $mid_sel, ROW_NUMBER() OVER( $rno_ord ) AS $idx_name FROM (
SELECT $sq_attrs->{selection_inner} $sq_attrs->{query_leftover}${group_having}
) $qalias
) $qalias WHERE $idx_name >= ? AND $idx_name <= ?
EOS
}
# some databases are happy with OVER (), some need OVER (ORDER BY (SELECT (1)) )
sub _rno_default_order {
return undef;
}
=head2 SkipFirst
SELECT SKIP $offset FIRST $limit * FROM ...
Suported by B<Informix>, almost like LimitOffset. According to
L<SQL::Abstract::Limit> C<... SKIP $offset LIMIT $limit ...> is also supported.
=cut
sub _SkipFirst {
my ($self, $sql, $rs_attrs, $rows, $offset) = @_;
$sql =~ s/^ \s* SELECT \s+ //ix
or $self->throw_exception("Unrecognizable SELECT: $sql");
return sprintf ('SELECT %s%s%s%s',
$offset
? do {
push @{$self->{pre_select_bind}}, [ $self->__offset_bindtype => $offset];
'SKIP ? '
}
: ''
,
do {
push @{$self->{pre_select_bind}}, [ $self->__rows_bindtype => $rows ];
'FIRST ? '
},
$sql,
$self->_parse_rs_attrs ($rs_attrs),
);
}
=head2 FirstSkip
SELECT FIRST $limit SKIP $offset * FROM ...
Supported by B<Firebird/Interbase>, reverse of SkipFirst. According to
L<SQL::Abstract::Limit> C<... ROWS $limit TO $offset ...> is also supported.
=cut
sub _FirstSkip {
my ($self, $sql, $rs_attrs, $rows, $offset) = @_;
$sql =~ s/^ \s* SELECT \s+ //ix
or $self->throw_exception("Unrecognizable SELECT: $sql");
return sprintf ('SELECT %s%s%s%s',
do {
push @{$self->{pre_select_bind}}, [ $self->__rows_bindtype => $rows ];
'FIRST ? '
},
$offset
? do {
push @{$self->{pre_select_bind}}, [ $self->__offset_bindtype => $offset];
'SKIP ? '
}
: ''
,
$sql,
$self->_parse_rs_attrs ($rs_attrs),
);
}
=head2 RowNum
Depending on the resultset attributes one of:
SELECT * FROM (
SELECT *, ROWNUM rownum__index FROM (
SELECT ...
) WHERE ROWNUM <= ($limit+$offset)
) WHERE rownum__index >= ($offset+1)
or
SELECT * FROM (
SELECT *, ROWNUM rownum__index FROM (
SELECT ...
)
) WHERE rownum__index BETWEEN ($offset+1) AND ($limit+$offset)
or
SELECT * FROM (
SELECT ...
) WHERE ROWNUM <= ($limit+1)
Supported by B<Oracle>.
=cut
sub _RowNum {
my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_;
my $sq_attrs = $self->_subqueried_limit_attrs ($sql, $rs_attrs);
my $qalias = $self->_quote ($rs_attrs->{alias});
my $idx_name = $self->_quote ('rownum__index');
my $order_group_having = $self->_parse_rs_attrs($rs_attrs);
# if no offset (e.g. first page) - we can skip one of the subqueries
if (! $offset) {
push @{$self->{limit_bind}}, [ $self->__rows_bindtype => $rows ];
return <<EOS;
SELECT $sq_attrs->{selection_outer} FROM (
SELECT $sq_attrs->{selection_inner} $sq_attrs->{query_leftover}${order_group_having}
) $qalias WHERE ROWNUM <= ?
EOS
}
#
# There are two ways to limit in Oracle, one vastly faster than the other
# on large resultsets: https://decipherinfosys.wordpress.com/2007/08/09/paging-and-countstopkey-optimization/
# However Oracle is retarded and does not preserve stable ROWNUM() values
# when called twice in the same scope. Therefore unless the resultset is
# ordered by a unique set of columns, it is not safe to use the faster
# method, and the slower BETWEEN query is used instead
#
# FIXME - this is quite expensive, and does not perform caching of any sort
# as soon as some of the DQ work becomes viable consider switching this
# over
if (
$rs_attrs->{order_by}
and
$rs_attrs->{_rsroot_rsrc}->storage->_order_by_is_stable(
@{$rs_attrs}{qw/from order_by where/}
)
) {
push @{$self->{limit_bind}}, [ $self->__total_bindtype => $offset + $rows ], [ $self->__offset_bindtype => $offset + 1 ];
return <<EOS;
SELECT $sq_attrs->{selection_outer} FROM (
SELECT $sq_attrs->{selection_outer}, ROWNUM $idx_name FROM (
SELECT $sq_attrs->{selection_inner} $sq_attrs->{query_leftover}${order_group_having}
) $qalias WHERE ROWNUM <= ?
) $qalias WHERE $idx_name >= ?
EOS
}
else {
push @{$self->{limit_bind}}, [ $self->__offset_bindtype => $offset + 1 ], [ $self->__total_bindtype => $offset + $rows ];
return <<EOS;
SELECT $sq_attrs->{selection_outer} FROM (
SELECT $sq_attrs->{selection_outer}, ROWNUM $idx_name FROM (
SELECT $sq_attrs->{selection_inner} $sq_attrs->{query_leftover}${order_group_having}
) $qalias
) $qalias WHERE $idx_name BETWEEN ? AND ?
EOS
}
}
# used by _Top and _FetchFirst below
sub _prep_for_skimming_limit {
my ( $self, $sql, $rs_attrs ) = @_;
# get selectors
my $sq_attrs = $self->_subqueried_limit_attrs ($sql, $rs_attrs);
my $requested_order = delete $rs_attrs->{order_by};
$sq_attrs->{order_by_requested} = $self->_order_by ($requested_order);
$sq_attrs->{grpby_having} = $self->_parse_rs_attrs ($rs_attrs);
# without an offset things are easy
if (! $rs_attrs->{offset}) {
$sq_attrs->{order_by_inner} = $sq_attrs->{order_by_requested};
}
else {
$sq_attrs->{quoted_rs_alias} = $self->_quote ($rs_attrs->{alias});
# localise as we already have all the bind values we need
local $self->{order_bind};
# make up an order unless supplied or sanity check what we are given
my $inner_order;
if ($sq_attrs->{order_by_requested}) {
$self->throw_exception (
'Unable to safely perform "skimming type" limit with supplied unstable order criteria'
) unless ($rs_attrs->{_rsroot_rsrc}->schema->storage->_order_by_is_stable(
$rs_attrs->{from},
$requested_order,
$rs_attrs->{where},
));
$inner_order = $requested_order;
}
else {
$inner_order = [ map
{ "$rs_attrs->{alias}.$_" }
( @{
$rs_attrs->{_rsroot_rsrc}->_identifying_column_set
||
$self->throw_exception(sprintf(
'Unable to auto-construct stable order criteria for "skimming type" limit '
. "dialect based on source '%s'", $rs_attrs->{_rsroot_rsrc}->name) );
} )
];
}
$sq_attrs->{order_by_inner} = $self->_order_by ($inner_order);
my @out_chunks;
for my $ch ($self->_order_by_chunks ($inner_order)) {
$ch = $ch->[0] if ref $ch eq 'ARRAY';
($ch, my $is_desc) = $self->_split_order_chunk($ch);
# !NOTE! outside chunks come in reverse order ( !$is_desc )
push @out_chunks, { ($is_desc ? '-asc' : '-desc') => \$ch };
}
$sq_attrs->{order_by_middle} = $self->_order_by (\@out_chunks);
# this is the order supplement magic
$sq_attrs->{selection_middle} = $sq_attrs->{selection_outer};
if (my $extra_order_sel = $sq_attrs->{order_supplement}) {
for my $extra_col (sort
{ $extra_order_sel->{$a} cmp $extra_order_sel->{$b} }
keys %$extra_order_sel
) {
$sq_attrs->{selection_inner} .= sprintf (', %s AS %s',
$extra_col,
$extra_order_sel->{$extra_col},
);
$sq_attrs->{selection_middle} .= ', ' . $extra_order_sel->{$extra_col};
}
# Whatever order bindvals there are, they will be realiased and
# reselected, and need to show up at end of the initial inner select
push @{$self->{select_bind}}, @{$self->{order_bind}};
}
# and this is order re-alias magic
for my $map ($sq_attrs->{order_supplement}, $sq_attrs->{outer_renames}) {
for my $col (sort { (length $b) <=> (length $a) } keys %{$map||{}}) {
my $re_col = quotemeta ($col);
$_ =~ s/$re_col/$map->{$col}/
for ($sq_attrs->{order_by_middle}, $sq_attrs->{order_by_requested});
}
}
}
$sq_attrs;
}
=head2 Top
SELECT * FROM
SELECT TOP $limit FROM (
SELECT TOP $limit FROM (
SELECT TOP ($limit+$offset) ...
) ORDER BY $reversed_original_order
) ORDER BY $original_order
Unreliable Top-based implementation, supported by B<< MSSQL < 2005 >>.
=head3 CAVEAT
Due to its implementation, this limit dialect returns B<incorrect results>
when $limit+$offset > total amount of rows in the resultset.
=cut
sub _Top {
my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_;
my $lim = $self->_prep_for_skimming_limit($sql, $rs_attrs);
$sql = sprintf ('SELECT TOP %u %s %s %s %s',
$rows + ($offset||0),
$offset ? $lim->{selection_inner} : $lim->{selection_original},
$lim->{query_leftover},
$lim->{grpby_having},
$lim->{order_by_inner},
);
$sql = sprintf ('SELECT TOP %u %s FROM ( %s ) %s %s',
$rows,
$lim->{selection_middle},
$sql,
$lim->{quoted_rs_alias},
$lim->{order_by_middle},
) if $offset;
$sql = sprintf ('SELECT %s FROM ( %s ) %s %s',
$lim->{selection_outer},
$sql,
$lim->{quoted_rs_alias},
$lim->{order_by_requested},
) if $offset and (
$lim->{order_by_requested} or $lim->{selection_middle} ne $lim->{selection_outer}
);
return $sql;
}
=head2 FetchFirst
SELECT * FROM
(
SELECT * FROM (
SELECT * FROM (
SELECT * FROM ...
) ORDER BY $reversed_original_order
FETCH FIRST $limit ROWS ONLY
) ORDER BY $original_order
FETCH FIRST $limit ROWS ONLY
)
Unreliable FetchFirst-based implementation, supported by B<< IBM DB2 <= V5R3 >>.
=head3 CAVEAT
Due to its implementation, this limit dialect returns B<incorrect results>
when $limit+$offset > total amount of rows in the resultset.
=cut
sub _FetchFirst {
my ( $self, $sql, $rs_attrs, $rows, $offset ) = @_;
my $lim = $self->_prep_for_skimming_limit($sql, $rs_attrs);
$sql = sprintf ('SELECT %s %s %s %s FETCH FIRST %u ROWS ONLY',
$offset ? $lim->{selection_inner} : $lim->{selection_original},
$lim->{query_leftover},
$lim->{grpby_having},
$lim->{order_by_inner},
$rows + ($offset||0),
);
$sql = sprintf ('SELECT %s FROM ( %s ) %s %s FETCH FIRST %u ROWS ONLY',
$lim->{selection_middle},
$sql,
$lim->{quoted_rs_alias},
$lim->{order_by_middle},
$rows,
) if $offset;
$sql = sprintf ('SELECT %s FROM ( %s ) %s %s',
$lim->{selection_outer},
$sql,
$lim->{quoted_rs_alias},
$lim->{order_by_requested},
) if $offset and (
$lim->{order_by_requested} or $lim->{selection_middle} ne $lim->{selection_outer}
);
return $sql;
}
=head2 GenericSubQ
SELECT * FROM (
SELECT ...
)
WHERE (
SELECT COUNT(*) FROM $original_table cnt WHERE cnt.id < $original_table.id
) BETWEEN $offset AND ($offset+$rows-1)
This is the most evil limit "dialect" (more of a hack) for I<really> stupid
databases. It works by ordering the set by some unique column, and calculating
the amount of rows that have a less-er value (thus emulating a L</RowNum>-like
index). Of course this implies the set can only be ordered by a single unique
column.
Also note that this technique can be and often is B<excruciatingly slow>. You
may have much better luck using L<DBIx::Class::ResultSet/software_limit>
instead.
Currently used by B<Sybase ASE>, due to lack of any other option.
=cut
sub _GenericSubQ {
my ($self, $sql, $rs_attrs, $rows, $offset) = @_;
my $root_rsrc = $rs_attrs->{_rsroot_rsrc};
# Explicitly require an order_by
# GenSubQ is slow enough as it is, just emulating things
# like in other cases is not wise - make the user work
# to shoot their DBA in the foot
my $supplied_order = delete $rs_attrs->{order_by} or $self->throw_exception (
'Generic Subquery Limit does not work on resultsets without an order. Provide a stable, '
. 'root-table-based order criteria.'
);
my $usable_order_ci = $root_rsrc->storage->_main_source_order_by_portion_is_stable(
$root_rsrc,
$supplied_order,
$rs_attrs->{where},
) or $self->throw_exception(
'Generic Subquery Limit can not work with order criteria based on sources other than the current one'
);
###
###
### we need to know the directions after we figured out the above - reextract *again*
### this is eyebleed - trying to get it to work at first
my @order_bits = do {
local $self->{quote_char};
local $self->{order_bind};
map { ref $_ ? $_->[0] : $_ } $self->_order_by_chunks ($supplied_order)
};
# truncate to what we'll use
$#order_bits = ( (keys %$usable_order_ci) - 1 );
# @order_bits likely will come back quoted (due to how the prefetch
# rewriter operates
# Hence supplement the column_info lookup table with quoted versions
if ($self->quote_char) {
$usable_order_ci->{$self->_quote($_)} = $usable_order_ci->{$_}
for keys %$usable_order_ci;
}
# calculate the condition
my $count_tbl_alias = 'rownum__emulation';
my $root_alias = $rs_attrs->{alias};
my $root_tbl_name = $root_rsrc->name;
my (@unqualified_names, @qualified_names, @is_desc, @new_order_by);
for my $bit (@order_bits) {
($bit, my $is_desc) = $self->_split_order_chunk($bit);
push @is_desc, $is_desc;
push @unqualified_names, $usable_order_ci->{$bit}{-colname};
push @qualified_names, $usable_order_ci->{$bit}{-fq_colname};
push @new_order_by, { ($is_desc ? '-desc' : '-asc') => $usable_order_ci->{$bit}{-fq_colname} };
};
my (@where_cond, @skip_colpair_stack);
for my $i (0 .. $#order_bits) {
my $ci = $usable_order_ci->{$order_bits[$i]};
my ($subq_col, $main_col) = map { "$_.$ci->{-colname}" } ($count_tbl_alias, $root_alias);
my $cur_cond = { $subq_col => { ($is_desc[$i] ? '>' : '<') => { -ident => $main_col } } };
push @skip_colpair_stack, [
{ $main_col => { -ident => $subq_col } },
];
# we can trust the nullability flag because
# we already used it during _id_col_set resolution
#
if ($ci->{is_nullable}) {
push @{$skip_colpair_stack[-1]}, { $main_col => undef, $subq_col=> undef };
$cur_cond = [
{
($is_desc[$i] ? $subq_col : $main_col) => { '!=', undef },
($is_desc[$i] ? $main_col : $subq_col) => undef,
},
{
$subq_col => { '!=', undef },
$main_col => { '!=', undef },
-and => $cur_cond,
},
];
}
push @where_cond, { '-and', => [ @skip_colpair_stack[0..$i-1], $cur_cond ] };
}
# reuse the sqlmaker WHERE, this will not be returning binds
my $counted_where = do {
local $self->{where_bind};
$self->where(\@where_cond);
};
# construct the rownum condition by hand
my $rownum_cond;
if ($offset) {
$rownum_cond = 'BETWEEN ? AND ?';
push @{$self->{limit_bind}},
[ $self->__offset_bindtype => $offset ],
[ $self->__total_bindtype => $offset + $rows - 1]
;
}
else {
$rownum_cond = '< ?';
push @{$self->{limit_bind}},
[ $self->__rows_bindtype => $rows ]
;
}
# and what we will order by inside
my $inner_order_sql = do {
local $self->{order_bind};
my $s = $self->_order_by (\@new_order_by);
$self->throw_exception('Inner gensubq order may not contain binds... something went wrong')
if @{$self->{order_bind}};
$s;
};
### resume originally scheduled programming
###
###
# we need to supply the order for the supplements to be properly calculated
my $sq_attrs = $self->_subqueried_limit_attrs (
$sql, { %$rs_attrs, order_by => \@new_order_by }
);
my $in_sel = $sq_attrs->{selection_inner};
# add the order supplement (if any) as this is what will be used for the outer WHERE
$in_sel .= ", $_" for sort keys %{$sq_attrs->{order_supplement}};
my $group_having_sql = $self->_parse_rs_attrs($rs_attrs);
return sprintf ("
SELECT $sq_attrs->{selection_outer}
FROM (
SELECT $in_sel $sq_attrs->{query_leftover}${group_having_sql}
) %s
WHERE ( SELECT COUNT(*) FROM %s %s $counted_where ) $rownum_cond
$inner_order_sql
", map { $self->_quote ($_) } (
$rs_attrs->{alias},
$root_tbl_name,
$count_tbl_alias,
));
}
# !!! THIS IS ALSO HORRIFIC !!! /me ashamed
#
# Generates inner/outer select lists for various limit dialects
# which result in one or more subqueries (e.g. RNO, Top, RowNum)
# Any non-root-table columns need to have their table qualifier
# turned into a column alias (otherwise names in subqueries clash
# and/or lose their source table)
#
# Returns mangled proto-sql, inner/outer strings of SQL QUOTED selectors
# with aliases (to be used in whatever select statement), and an alias
# index hashref of QUOTED SEL => QUOTED ALIAS pairs (to maybe be used
# for string-subst higher up).
# If an order_by is supplied, the inner select needs to bring out columns
# used in implicit (non-selected) orders, and the order condition itself
# needs to be realiased to the proper names in the outer query. Thus we
# also return a hashref (order doesn't matter) of QUOTED EXTRA-SEL =>
# QUOTED ALIAS pairs, which is a list of extra selectors that do *not*
# exist in the original select list
sub _subqueried_limit_attrs {
my ($self, $proto_sql, $rs_attrs) = @_;
$self->throw_exception(
'Limit dialect implementation usable only in the context of DBIC (missing $rs_attrs)'
) unless ref ($rs_attrs) eq 'HASH';
# mangle the input sql as we will be replacing the selector entirely
unless (
$rs_attrs->{_selector_sql}
and
$proto_sql =~ s/^ \s* SELECT \s* \Q$rs_attrs->{_selector_sql}//ix
) {
$self->throw_exception("Unrecognizable SELECT: $proto_sql");
}
my ($re_sep, $re_alias) = map { quotemeta $_ } ( $self->{name_sep}, $rs_attrs->{alias} );
# insulate from the multiple _recurse_fields calls below
local $self->{select_bind};
# correlate select and as, build selection index
my (@sel, $in_sel_index);
for my $i (0 .. $#{$rs_attrs->{select}}) {
my $s = $rs_attrs->{select}[$i];
my $sql_sel = $self->_recurse_fields ($s);
my $sql_alias = (ref $s) eq 'HASH' ? $s->{-as} : undef;
push @sel, {
arg => $s,
sql => $sql_sel,
unquoted_sql => do {
local $self->{quote_char};
$self->_recurse_fields ($s);
},
as =>
$sql_alias
||
$rs_attrs->{as}[$i]
||
$self->throw_exception("Select argument $i ($s) without corresponding 'as'")
,
};
# anything with a placeholder in it needs re-selection
$in_sel_index->{$sql_sel}++ unless $sql_sel =~ / (?: ^ | \W ) \? (?: \W | $ ) /x;
$in_sel_index->{$self->_quote ($sql_alias)}++ if $sql_alias;
# record unqualified versions too, so we do not have
# to reselect the same column twice (in qualified and
# unqualified form)
if (! ref $s && $sql_sel =~ / $re_sep (.+) $/x) {
$in_sel_index->{$1}++;
}
}
# re-alias and remove any name separators from aliases,
# unless we are dealing with the current source alias
# (which will transcend the subqueries as it is necessary
# for possible further chaining)
# same for anything we do not recognize
my ($sel, $renamed);
for my $node (@sel) {
push @{$sel->{original}}, $node->{sql};
if (
! $in_sel_index->{$node->{sql}}
or
$node->{as} =~ / (?<! ^ $re_alias ) \. /x
or
$node->{unquoted_sql} =~ / (?<! ^ $re_alias ) $re_sep /x
) {
$node->{as} = $self->_unqualify_colname($node->{as});
my $quoted_as = $self->_quote($node->{as});
push @{$sel->{inner}}, sprintf '%s AS %s', $node->{sql}, $quoted_as;
push @{$sel->{outer}}, $quoted_as;
$renamed->{$node->{sql}} = $quoted_as;
}
else {
push @{$sel->{inner}}, $node->{sql};
push @{$sel->{outer}}, $self->_quote (ref $node->{arg} ? $node->{as} : $node->{arg});
}
}
# see if the order gives us anything
my $extra_order_sel;
for my $chunk ($self->_order_by_chunks ($rs_attrs->{order_by})) {
# order with bind
$chunk = $chunk->[0] if (ref $chunk) eq 'ARRAY';
($chunk) = $self->_split_order_chunk($chunk);
next if $in_sel_index->{$chunk};
$extra_order_sel->{$chunk} ||= $self->_quote (
'ORDER__BY__' . sprintf '%03d', scalar keys %{$extra_order_sel||{}}
);
}
return {
query_leftover => $proto_sql,
(map {( "selection_$_" => join (', ', @{$sel->{$_}} ) )} keys %$sel ),
outer_renames => $renamed,
order_supplement => $extra_order_sel,
};
}
sub _unqualify_colname {
my ($self, $fqcn) = @_;
$fqcn =~ s/ \. /__/xg;
return $fqcn;
}
1;
=head1 AUTHORS
See L<DBIx::Class/CONTRIBUTORS>.
=head1 LICENSE
You may distribute this code under the same terms as Perl itself.
=cut
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