}
sub _select_args {
- my ($self, $ident, $select, $condition, $attrs) = @_;
+ my ($self, $ident, $select, $where, $attrs) = @_;
my $sql_maker = $self->sql_maker;
$sql_maker->{_dbic_rs_attrs} = $attrs;
- my $order = { map
- { $attrs->{$_} ? ( $_ => $attrs->{$_} ) : () }
- (qw/order_by group_by having _virtual_order_by/ )
- };
-
-
- my $bind_attrs = {};
-
my $alias2source = $self->_resolve_ident_sources ($ident);
+ # calculate bind_attrs before possible $ident mangling
+ my $bind_attrs = {};
for my $alias (keys %$alias2source) {
my $bindtypes = $self->source_bind_attributes ($alias2source->{$alias}) || {};
for my $col (keys %$bindtypes) {
}
}
- # This would be the point to deflate anything found in $condition
- # (and leave $attrs->{bind} intact). Problem is - inflators historically
- # expect a row object. And all we have is a resultsource (it is trivial
- # to extract deflator coderefs via $alias2source above).
- #
- # I don't see a way forward other than changing the way deflators are
- # invoked, and that's just bad...
-
- my @args = ('select', $attrs->{bind}, $ident, $bind_attrs, $select, $condition, $order);
+ my @limit;
if ($attrs->{software_limit} ||
$sql_maker->_default_limit_syntax eq "GenericSubQ") {
$attrs->{software_limit} = 1;
# MySQL actually recommends this approach. I cringe.
$attrs->{rows} = 2**48 if not defined $attrs->{rows} and defined $attrs->{offset};
- push @args, $attrs->{rows}, $attrs->{offset};
+
+ if ($attrs->{rows} && keys %{$attrs->{collapse}}) {
+ ($ident, $select, $where, $attrs)
+ = $self->_adjust_select_args_for_limited_prefetch ($ident, $select, $where, $attrs);
+ }
+ else {
+ push @limit, $attrs->{rows}, $attrs->{offset};
+ }
}
- return @args;
+
+###
+ # This would be the point to deflate anything found in $where
+ # (and leave $attrs->{bind} intact). Problem is - inflators historically
+ # expect a row object. And all we have is a resultsource (it is trivial
+ # to extract deflator coderefs via $alias2source above).
+ #
+ # I don't see a way forward other than changing the way deflators are
+ # invoked, and that's just bad...
+###
+
+ my $order = { map
+ { $attrs->{$_} ? ( $_ => $attrs->{$_} ) : () }
+ (qw/order_by group_by having _virtual_order_by/ )
+ };
+
+
+ $sql_maker->{for} = delete $attrs->{for};
+
+ return ('select', $attrs->{bind}, $ident, $bind_attrs, $select, $where, $order, @limit);
+}
+
+sub _adjust_select_args_for_limited_prefetch {
+ my ($self, $from, $select, $where, $attrs) = @_;
+
+ if ($attrs->{group_by} and @{$attrs->{group_by}}) {
+ $self->throw_exception ('Prefetch with limit (rows/offset) is not supported on resultsets with a group_by attribute');
+ }
+
+ $self->throw_exception ('Prefetch with limit (rows/offset) is not supported on resultsets with a custom from attribute')
+ if (ref $from ne 'ARRAY');
+
+ # separate attributes
+ my $sub_attrs = { %$attrs };
+ delete $attrs->{$_} for qw/where bind rows offset/;
+ delete $sub_attrs->{$_} for qw/for collapse select order_by/;
+
+ my $alias = $attrs->{alias};
+
+ # create subquery select list
+ my $sub_select = [ grep { $_ =~ /^$alias\./ } @{$attrs->{select}} ];
+
+ # bring over all non-collapse-induced order_by into the inner query (if any)
+ # the outer one will have to keep them all
+ if (my $ord_cnt = @{$attrs->{order_by}} - @{$attrs->{_collapse_order_by}} ) {
+ $sub_attrs->{order_by} = [
+ @{$attrs->{order_by}}[ 0 .. ($#{$attrs->{order_by}} - $ord_cnt - 1) ]
+ ];
+ }
+
+
+ # mangle the head of the {from}
+ my $self_ident = shift @$from;
+
+ my %join_info = map { $_->[0]{-alias} => $_->[0] } (@$from);
+
+ my (%inner_joins);
+
+ # decide which parts of the join will remain on the inside
+ #
+ # this is not a very viable optimisation, but it was written
+ # before I realised this, so might as well remain. We can throw
+ # away _any_ branches of the join tree that are:
+ # 1) not mentioned in the condition/order
+ # 2) left-join leaves (or left-join leaf chains)
+ # Most of the join ocnditions will not satisfy this, but for real
+ # complex queries some might, and we might make some RDBMS happy.
+ #
+ #
+ # since we do not have introspectable SQLA, we fall back to ugly
+ # scanning of raw SQL for WHERE, and for pieces of ORDER BY
+ # in order to determine what goes into %inner_joins
+ # It may not be very efficient, but it's a reasonable stop-gap
+ {
+ # produce stuff unquoted, so it can be scanned
+ my $sql_maker = $self->sql_maker;
+ local $sql_maker->{quote_char};
+
+ my @order_by = (map
+ { ref $_ ? $_->[0] : $_ }
+ $sql_maker->_order_by_chunks ($sub_attrs->{order_by})
+ );
+
+ my $where_sql = $sql_maker->where ($where);
+
+ # sort needed joins
+ for my $alias (keys %join_info) {
+
+ # any table alias found on a column name in where or order_by
+ # gets included in %inner_joins
+ # Also any parent joins that are needed to reach this particular alias
+ for my $piece ($where_sql, @order_by ) {
+ if ($piece =~ /\b$alias\./) {
+ $inner_joins{$alias} = 1;
+ }
+ }
+ }
+ }
+
+ # scan for non-leaf/non-left joins and mark as needed
+ # also mark all ancestor joins that are needed to reach this particular alias
+ # (e.g. join => { cds => 'tracks' } - tracks will bring cds too )
+ #
+ # traverse by the size of the -join_path i.e. reverse depth first
+ for my $alias (sort { @{$join_info{$b}{-join_path}} <=> @{$join_info{$a}{-join_path}} } (keys %join_info) ) {
+
+ my $j = $join_info{$alias};
+ $inner_joins{$alias} = 1 if (! $j->{-join_type} || ($j->{-join_type} !~ /^left$/i) );
+
+ if ($inner_joins{$alias}) {
+ $inner_joins{$_} = 1 for (@{$j->{-join_path}});
+ }
+ }
+
+ # construct the inner $from for the subquery
+ my $inner_from = [ $self_ident ];
+ if (keys %inner_joins) {
+ for my $j (@$from) {
+ push @$inner_from, $j if $inner_joins{$j->[0]{-alias}};
+ }
+
+ # if a multi-type join was needed in the subquery ("multi" is indicated by
+ # presence in {collapse}) - add a group_by to simulate the collapse in the subq
+ for my $alias (keys %inner_joins) {
+
+ # the dot comes from some weirdness in collapse
+ # remove after the rewrite
+ if ($attrs->{collapse}{".$alias"}) {
+ $sub_attrs->{group_by} = $sub_select;
+ last;
+ }
+ }
+ }
+
+ # generate the subquery
+ my $subq = $self->_select_args_to_query (
+ $inner_from,
+ $sub_select,
+ $where,
+ $sub_attrs
+ );
+
+ # put it back in $from
+ unshift @$from, { $alias => $subq };
+
+ # This is totally horrific - the $where ends up in both the inner and outer query
+ # Unfortunately not much can be done until SQLA2 introspection arrives
+ #
+ # OTOH it can be seen as a plus: <ash> (notes that this query would make a DBA cry ;)
+ return ($from, $select, $where, $attrs);
}
sub _resolve_ident_sources {
my $tmp_attrs = { %$attrs };
- # take off any pagers, record_filter is cdbi, and no point of ordering a count
- delete $tmp_attrs->{$_} for (qw/select as rows offset page order_by record_filter/);
+ # take off any limits, record_filter is cdbi, and no point of ordering a count
+ delete $tmp_attrs->{$_} for (qw/select as rows offset order_by record_filter/);
# overwrite the selector
$tmp_attrs->{select} = { count => '*' };
my $sub_attrs = { %$attrs };
# these can not go in the subquery, and there is no point of ordering it
- delete $sub_attrs->{$_} for qw/prefetch collapse select as order_by/;
+ delete $sub_attrs->{$_} for qw/collapse select as order_by/;
# if we prefetch, we group_by primary keys only as this is what we would get out of the rs via ->next/->all
# simply deleting group_by suffices, as the code below will re-fill it
}];
# the subquery replaces this
- delete $attrs->{$_} for qw/where bind prefetch collapse group_by having having_bind rows offset page pager/;
+ delete $attrs->{$_} for qw/where bind collapse group_by having having_bind rows offset/;
return $self->count ($source, $attrs);
}
projects / dbsrgits/DBIx-Class.git / blobdiff