sub _adjust_select_args_for_complex_prefetch {
my ($self, $from, $select, $where, $attrs) = @_;
- $self->throw_exception ('Complex prefetches are not supported on resultsets with a custom from attribute')
- if (ref $from ne 'ARRAY');
-
- # copies for mangling
- $from = [ @$from ];
- $select = [ @$select ];
- $attrs = { %$attrs };
+ $self->throw_exception ('Nothing to prefetch... how did we get here?!')
+ if not @{$attrs->{_prefetch_select}};
- # separate attributes
- my $sub_attrs = { %$attrs };
- delete $attrs->{$_} for qw/where bind rows offset group_by having/;
- delete $sub_attrs->{$_} for qw/for collapse _prefetch_select _collapse_order_by select as/;
+ $self->throw_exception ('Complex prefetches are not supported on resultsets with a custom from attribute')
+ if (ref $from ne 'ARRAY' || ref $from->[0] ne 'HASH' || ref $from->[1] ne 'ARRAY');
- my $select_root_alias = $attrs->{alias};
- my $sql_maker = $self->sql_maker;
- # create subquery select list - consider only stuff *not* brought in by the prefetch
- my $sub_select = [];
- my $sub_group_by;
- for my $i (0 .. @{$attrs->{select}} - @{$attrs->{_prefetch_select}} - 1) {
- my $sel = $attrs->{select}[$i];
+ # generate inner/outer attribute lists, remove stuff that doesn't apply
+ my $outer_attrs = { %$attrs };
+ delete $outer_attrs->{$_} for qw/where bind rows offset group_by having/;
- # alias any functions to the dbic-side 'as' label
- # adjust the outer select accordingly
- if (ref $sel eq 'HASH' ) {
- $sel->{-as} ||= $attrs->{as}[$i];
- $select->[$i] = join ('.', $attrs->{alias}, ($sel->{-as} || "select_$i") );
- }
+ my $inner_attrs = { %$attrs };
+ delete $inner_attrs->{$_} for qw/for collapse _prefetch_select _collapse_order_by select as/;
- push @$sub_select, $sel;
- }
# bring over all non-collapse-induced order_by into the inner query (if any)
# the outer one will have to keep them all
- delete $sub_attrs->{order_by};
- if (my $ord_cnt = @{$attrs->{order_by}} - @{$attrs->{_collapse_order_by}} ) {
- $sub_attrs->{order_by} = [
- @{$attrs->{order_by}}[ 0 .. $ord_cnt - 1]
+ delete $inner_attrs->{order_by};
+ if (my $ord_cnt = @{$outer_attrs->{order_by}} - @{$outer_attrs->{_collapse_order_by}} ) {
+ $inner_attrs->{order_by} = [
+ @{$outer_attrs->{order_by}}[ 0 .. $ord_cnt - 1]
];
}
- # mangle {from}, keep in mind that $from is "headless" from here on
- my $join_root = shift @$from;
- my %inner_joins;
- my %join_info = map { $_->[0]{-alias} => $_->[0] } (@$from);
+ # generate the inner/outer select lists
+ # for inside we consider only stuff *not* brought in by the prefetch
+ # on the outside we substitute any function for its alias
+ my $outer_select = [ @$select ];
+ my $inner_select = [];
+ for my $i (0 .. ( @$outer_select - @{$outer_attrs->{_prefetch_select}} - 1) ) {
+ my $sel = $outer_select->[$i];
+
+ if (ref $sel eq 'HASH' ) {
+ $sel->{-as} ||= $attrs->{as}[$i];
+ $outer_select->[$i] = join ('.', $attrs->{alias}, ($sel->{-as} || "inner_column_$i") );
+ }
+
+ push @$inner_select, $sel;
+ }
+
+ # normalize a copy of $from, so it will be easier to work with further
+ # down (i.e. promote the initial hashref to an AoH)
+ $from = [ @$from ];
+ $from->[0] = [ $from->[0] ];
+ my %original_join_info = map { $_->[0]{-alias} => $_->[0] } (@$from);
- # in complex search_related chains $select_root_alias may *not* be
- # 'me' so always include it in the inner join
- $inner_joins{$select_root_alias} = 1 if ($join_root->{-alias} ne $select_root_alias);
+ # decide which parts of the join will remain in either part of
+ # the outer/inner query
- # decide which parts of the join will remain on the inside
- #
- # this is not a very viable optimisation, but it was written
- # before I realised this, so might as well remain. We can throw
- # away _any_ branches of the join tree that are:
- # 1) not mentioned in the condition/order
- # 2) left-join leaves (or left-join leaf chains)
- # Most of the join conditions will not satisfy this, but for real
- # complex queries some might, and we might make some RDBMS happy.
- #
- #
- # since we do not have introspectable SQLA, we fall back to ugly
- # scanning of raw SQL for WHERE, and for pieces of ORDER BY
- # in order to determine what goes into %inner_joins
+ # First we compose a list of which aliases are used in restrictions
+ # (i.e. conditions/order/grouping/etc). Since we do not have
+ # introspectable SQLA, we fall back to ugly scanning of raw SQL for
+ # WHERE, and for pieces of ORDER BY in order to determine which aliases
+ # need to appear in the resulting sql.
# It may not be very efficient, but it's a reasonable stop-gap
+ # Also unqualified column names will not be considered, but more often
+ # than not this is actually ok
+ #
+ # In the same loop we enumerate part of the selection aliases, as
+ # it requires the same sqla hack for the time being
+ my ($restrict_aliases, $select_aliases, $prefetch_aliases);
{
# produce stuff unquoted, so it can be scanned
+ my $sql_maker = $self->sql_maker;
local $sql_maker->{quote_char};
my $sep = $self->_sql_maker_opts->{name_sep} || '.';
$sep = "\Q$sep\E";
- my @order_by = (map
+ my $non_prefetch_select_sql = $sql_maker->_recurse_fields ($inner_select);
+ my $prefetch_select_sql = $sql_maker->_recurse_fields ($outer_attrs->{_prefetch_select});
+ my $where_sql = $sql_maker->where ($where);
+ my $group_by_sql = $sql_maker->_order_by({
+ map { $_ => $inner_attrs->{$_} } qw/group_by having/
+ });
+ my @non_prefetch_order_by_chunks = (map
{ ref $_ ? $_->[0] : $_ }
- $sql_maker->_order_by_chunks ($sub_attrs->{order_by})
+ $sql_maker->_order_by_chunks ($inner_attrs->{order_by})
);
- my $where_sql = $sql_maker->where ($where);
- my $select_sql = $sql_maker->_recurse_fields ($sub_select);
- # sort needed joins
- for my $alias (keys %join_info) {
+ for my $alias (keys %original_join_info) {
+ my $seen_re = qr/\b $alias $sep/x;
- # 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 $piece ($select_sql, $where_sql, @order_by ) {
- if ($piece =~ /\b $alias $sep/x) {
- $inner_joins{$alias} = 1;
+ for my $piece ($where_sql, $group_by_sql, @non_prefetch_order_by_chunks ) {
+ if ($piece =~ $seen_re) {
+ $restrict_aliases->{$alias} = 1;
}
}
+
+ if ($non_prefetch_select_sql =~ $seen_re) {
+ $select_aliases->{$alias} = 1;
+ }
+
+ if ($prefetch_select_sql =~ $seen_re) {
+ $prefetch_aliases->{$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) );
+ # Add any non-left joins to the restriction list (such joins are indeed restrictions)
+ for my $j (values %original_join_info) {
+ my $alias = $j->{-alias} or next;
+ $restrict_aliases->{$alias} = 1 if (
+ (not $j->{-join_type})
+ or
+ ($j->{-join_type} !~ /^left (?: \s+ outer)? $/xi)
+ );
+ }
- if ($inner_joins{$alias}) {
- $inner_joins{$_} = 1 for (@{$j->{-join_path}});
+ # mark all join parents as mentioned
+ # (e.g. join => { cds => 'tracks' } - tracks will need to bring cds too )
+ for my $collection ($restrict_aliases, $select_aliases) {
+ for my $alias (keys %$collection) {
+ $collection->{$_} = 1
+ for (@{ $original_join_info{$alias}{-join_path} || [] });
}
}
# construct the inner $from for the subquery
- my $inner_from = [ $join_root ];
+ my %inner_joins = (map { %{$_ || {}} } ($restrict_aliases, $select_aliases) );
+ my @inner_from;
for my $j (@$from) {
- push @$inner_from, $j if $inner_joins{$j->[0]{-alias}};
+ 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
- unless ($sub_attrs->{group_by}) {
+ unless ($inner_attrs->{group_by}) {
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;
+ $inner_attrs->{group_by} ||= $inner_select;
last;
}
}
}
+ # demote the inner_from head
+ $inner_from[0] = $inner_from[0][0];
+
# generate the subquery
my $subq = $self->_select_args_to_query (
- $inner_from,
- $sub_select,
+ \@inner_from,
+ $inner_select,
$where,
- $sub_attrs
+ $inner_attrs,
);
+
my $subq_joinspec = {
- -alias => $select_root_alias,
- -source_handle => $join_root->{-source_handle},
- $select_root_alias => $subq,
+ -alias => $attrs->{alias},
+ -source_handle => $inner_from[0]{-source_handle},
+ $attrs->{alias} => $subq,
};
- # Generate a new from (really just replace the join slot with the subquery)
- # Before we would start the outer chain from the subquery itself (i.e.
- # SELECT ... FROM (SELECT ... ) alias JOIN ..., but this turned out to be
- # a bad idea for search_related, as the root of the chain was effectively
- # lost (i.e. $artist_rs->search_related ('cds'... ) would result in alias
- # of 'cds', which would prevent from doing things like order_by artist.*)
- # See t/prefetch/via_search_related.t for a better idea
+ # Generate the outer from - this is relatively easy (really just replace
+ # the join slot with the subquery), with a major caveat - we can not
+ # join anything that is non-selecting (not part of the prefetch), but at
+ # the same time is a multi-type relationship, as it will explode the result.
+ #
+ # There are two possibilities here
+ # - either the join is non-restricting, in which case we simply throw it away
+ # - it is part of the restrictions, in which case we need to collapse the outer
+ # result by tackling yet another group_by to the outside of the query
+
+ # so first generate the outer_from, up to the substitution point
my @outer_from;
- if ($join_root->{-alias} eq $select_root_alias) { # just swap the root part and we're done
- @outer_from = (
- $subq_joinspec,
- @$from,
- )
+ while (my $j = shift @$from) {
+ if ($j->[0]{-alias} eq $attrs->{alias}) { # time to swap
+ push @outer_from, [
+ $subq_joinspec,
+ @{$j}[1 .. $#$j],
+ ];
+ last; # we'll take care of what's left in $from below
+ }
+ else {
+ push @outer_from, $j;
+ }
}
- else { # this is trickier
- @outer_from = ($join_root);
-
- for my $j (@$from) {
- if ($j->[0]{-alias} eq $select_root_alias) {
- push @outer_from, [
- $subq_joinspec,
- @{$j}[1 .. $#$j],
- ];
- }
- else {
- push @outer_from, $j;
- }
+
+ # see what's left - throw away if not selecting/restricting
+ # also throw in a group_by if restricting to guard against
+ # cross-join explosions
+ #
+ while (my $j = shift @$from) {
+ my $alias = $j->[0]{-alias};
+
+ if ($select_aliases->{$alias} || $prefetch_aliases->{$alias}) {
+ push @outer_from, $j;
+ }
+ elsif ($restrict_aliases->{$alias}) {
+ push @outer_from, $j;
+
+ # FIXME - this should be obviated by SQLA2, as I'll be able to
+ # have restrict_inner and restrict_outer... or something to that
+ # effect... I think...
+
+ # FIXME2 - I can't find a clean way to determine if a particular join
+ # is a multi - instead I am just treating everything as a potential
+ # explosive join (ribasushi)
+ #
+ # if (my $handle = $j->[0]{-source_handle}) {
+ # my $rsrc = $handle->resolve;
+ # ... need to bail out of the following if this is not a multi,
+ # as it will be much easier on the db ...
+
+ $outer_attrs->{group_by} ||= $outer_select;
+ # }
}
}
+ # demote the outer_from head
+ $outer_from[0] = $outer_from[0][0];
+
# 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, and even
# then if where conditions apply to the *right* side of the prefetch, you may have
# the outer select to exclude joins you didin't want in the first place
#
# OTOH it can be seen as a plus: <ash> (notes that this query would make a DBA cry ;)
- return (\@outer_from, $select, $where, $attrs);
+ return (\@outer_from, $outer_select, $where, $outer_attrs);
}
sub _resolve_ident_sources {
}
{
- $schema->storage->debug(1);
- my $cd_rs = $schema->resultset('CD')->search(undef, {
+ my $cd_rs = $schema->resultset('CD')->search({}, {
distinct => 1,
join => [qw/ tracks /],
prefetch => [qw/ artist /],
});
-
- is($cd_rs->all, 5, 'search with has_many join and distinct ok');
- $schema->storage->debug(0);
+ is($cd_rs->count, 5, 'complex prefetch + non-prefetching has_many join count correct');
+ is($cd_rs->all, 5, 'complex prefetch + non-prefetching has_many join number of objects correct');
+
+ # try the same as above, but add a condition so the tracks join can not be thrown away
+ my $cd_rs2 = $cd_rs->search ({ 'tracks.title' => { '!=' => 'ugabuganoexist' } });
+ is($cd_rs2->count, 5, 'complex prefetch + non-prefetching restricted has_many join count correct');
+ is($cd_rs2->all, 5, 'complex prefetch + non-prefetching restricted has_many join number of objects correct');
+
+ # the outer group_by seems like a necessary evil, if someone can figure out how to take it away
+ # without breaking compat - be my guest
+ is_same_sql_bind (
+ $cd_rs2->as_query,
+ '(
+ SELECT me.cdid, me.artist, me.title, me.year, me.genreid, me.single_track,
+ artist.artistid, artist.name, artist.rank, artist.charfield
+ FROM (
+ SELECT me.cdid, me.artist, me.title, me.year, me.genreid, me.single_track
+ FROM cd me
+ LEFT JOIN track tracks ON tracks.cd = me.cdid
+ JOIN artist artist ON artist.artistid = me.artist
+ WHERE ( tracks.title != ? )
+ GROUP BY me.cdid, me.artist, me.title, me.year, me.genreid, me.single_track
+ ) me
+ LEFT JOIN track tracks ON tracks.cd = me.cdid
+ JOIN artist artist ON artist.artistid = me.artist
+ WHERE ( tracks.title != ? )
+ GROUP BY me.cdid, me.artist, me.title, me.year, me.genreid, me.single_track,
+ artist.artistid, artist.name, artist.rank, artist.charfield
+ )',
+ [ map { [ 'tracks.title' => 'ugabuganoexist' ] } (1 .. 2) ],
+ );
}
done_testing;
projects / dbsrgits/DBIx-Class.git / commitdiff