From: Peter Rabbitson Date: Sat, 20 Jun 2009 10:44:09 +0000 (+0000) Subject: Add count_rs, move the code back from DBI - leave only sql specific hooks X-Git-Tag: v0.08108~72^2~2 X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=5960a19503062a9725068f9e8ed067b9ab6e8293;p=dbsrgits%2FDBIx-Class.git Add count_rs, move the code back from DBI - leave only sql specific hooks --- diff --git a/lib/DBIx/Class/ResultSet.pm b/lib/DBIx/Class/ResultSet.pm index 6faf118..b4fc281 100644 --- a/lib/DBIx/Class/ResultSet.pm +++ b/lib/DBIx/Class/ResultSet.pm @@ -1154,17 +1154,122 @@ sub count { return $self->search(@_)->count if @_ and defined $_[0]; return scalar @{ $self->get_cache } if $self->get_cache; - my $meth = $self->_has_resolved_attr (qw/collapse group_by/) - ? 'count_grouped' - : 'count' - ; - my $attrs = $self->_resolved_attrs_copy; + + # this is a little optimization - it is faster to do the limit + # adjustments in software, instead of a subquery + my $rows = delete $attrs->{rows}; + my $offset = delete $attrs->{offset}; + + my $crs; + if ($self->_has_resolved_attr (qw/collapse group_by/)) { + $crs = $self->_count_subq_rs ($attrs); + } + else { + $crs = $self->_count_rs ($attrs); + } + my $count = $crs->next; + + $count -= $offset if $offset; + $count = $rows if $rows and $rows < $count; + $count = 0 if ($count < 0); + + return $count; +} + +=head2 count_rs + +=over 4 + +=item Arguments: $cond, \%attrs?? + +=item Return Value: $count_rs + +=back + +Same as L but returns a L object. +This can be very handy for subqueries: + + ->search( { amount => $some_rs->count_rs->as_query } ) + +As with regular resultsets the SQL query will be executed only after +the resultset is accessed via L or L. That would return +the same single value obtainable via L. + +=cut + +sub count_rs { + my $self = shift; + return $self->search(@_)->count_rs if @_; + + # this may look like a lack of abstraction (count() does about the same) + # but in fact an _rs *must* use a subquery for the limits, as the + # software based limiting can not be ported if this $rs is to be used + # in a subquery itself (i.e. ->as_query) + if ($self->_has_resolved_attr (qw/collapse group_by offset rows/)) { + return $self->_count_subq_rs; + } + else { + return $self->_count_rs; + } +} + +# +# returns a ResultSetColumn object tied to the count query +# +sub _count_rs { + my ($self, $attrs) = @_; + + my $rsrc = $self->result_source; + $attrs ||= $self->_resolved_attrs; + + my $tmp_attrs = { %$attrs }; + + # 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 (supplied by the storage) + $tmp_attrs->{select} = $rsrc->storage->_count_select ($rsrc, $tmp_attrs); + $tmp_attrs->{as} = 'count'; + + my $tmp_rs = $rsrc->resultset_class->new($rsrc, $tmp_attrs)->get_column ('count'); + + return $tmp_rs; +} + +# +# same as above but uses a subquery +# +sub _count_subq_rs { + my ($self, $attrs) = @_; + my $rsrc = $self->result_source; + $attrs ||= $self->_resolved_attrs_copy; - return $rsrc->storage->$meth ($rsrc, $attrs); + my $sub_attrs = { %$attrs }; + + # these can not go in the subquery, and there is no point of ordering it + 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 + # clobber old group_by regardless + if ( keys %{$attrs->{collapse}} ) { + $sub_attrs->{group_by} = [ map { "$attrs->{alias}.$_" } ($rsrc->primary_columns) ] + } + + $sub_attrs->{select} = $rsrc->storage->_subq_count_select ($rsrc, $sub_attrs); + + $attrs->{from} = [{ + count_subq => $rsrc->resultset_class->new ($rsrc, $sub_attrs )->as_query + }]; + + # the subquery replaces this + delete $attrs->{$_} for qw/where bind collapse group_by having having_bind rows offset/; + + return $self->_count_rs ($attrs); } + sub _bool { return 1; } @@ -2571,22 +2676,24 @@ sub _resolved_attrs { $self->{attrs}{alias} => $source->from, } ]; - if ( exists $attrs->{join} || exists $attrs->{prefetch} ) { + if ( $attrs->{join} || $attrs->{prefetch} ) { + + $self->throw_exception ('join/prefetch can not be used with a literal scalarref {from}') + if ref $attrs->{from} ne 'ARRAY'; + my $join = delete $attrs->{join} || {}; if ( defined $attrs->{prefetch} ) { $join = $self->_merge_attr( $join, $attrs->{prefetch} ); - } $attrs->{from} = # have to copy here to avoid corrupting the original [ - @{ $attrs->{from} }, - $source->_resolve_join( - $join, $alias, { %{ $attrs->{seen_join} || {} } } - ) + @{ $attrs->{from} }, + $source->_resolve_join( + $join, $alias, { %{ $attrs->{seen_join} || {} } } + ) ]; - } if ( $attrs->{order_by} ) { diff --git a/lib/DBIx/Class/Storage/DBI.pm b/lib/DBIx/Class/Storage/DBI.pm index e0799df..707b305 100644 --- a/lib/DBIx/Class/Storage/DBI.pm +++ b/lib/DBIx/Class/Storage/DBI.pm @@ -1446,75 +1446,37 @@ sub _resolve_ident_sources { return $alias2source; } -sub count { - my ($self, $source, $attrs) = @_; - - my $tmp_attrs = { %$attrs }; - - # 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 $tmp_rs = $source->resultset_class->new($source, $tmp_attrs); - my ($count) = $tmp_rs->cursor->next; - - # if the offset/rows attributes are still present, we did not use - # a subquery, so we need to make the calculations in software - $count -= $attrs->{offset} if $attrs->{offset}; - $count = $attrs->{rows} if $attrs->{rows} and $attrs->{rows} < $count; - $count = 0 if ($count < 0); - - return $count; -} - -sub count_grouped { - my ($self, $source, $attrs) = @_; - - # copy for the subquery, we need to do some adjustments to it too - my $sub_attrs = { %$attrs }; - - # these can not go in the subquery, and there is no point of ordering it - 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 - # Note: we check $attrs, as $sub_attrs has collapse deleted - if (ref $attrs->{collapse} and keys %{$attrs->{collapse}} ) { - delete $sub_attrs->{group_by}; - } - - $sub_attrs->{group_by} ||= [ map { "$attrs->{alias}.$_" } ($source->primary_columns) ]; - $sub_attrs->{select} = $self->_grouped_count_select ($source, $sub_attrs); - - $attrs->{from} = [{ - count_subq => $source->resultset_class->new ($source, $sub_attrs )->as_query - }]; - - # the subquery replaces this - delete $attrs->{$_} for qw/where bind collapse group_by having having_bind rows offset/; - - return $self->count ($source, $attrs); -} - +# Returns a counting SELECT for a simple count +# query. Abstracted so that a storage could override +# this to { count => 'firstcol' } or whatever makes +# sense as a performance optimization +sub _count_select { + #my ($self, $source, $rs_attrs) = @_; + return { count => '*' }; +} + +# Returns a SELECT which will end up in the subselect +# There may or may not be a group_by, as the subquery +# might have been called to accomodate a limit # -# Returns a SELECT to go with a supplied GROUP BY -# (caled by count_grouped so a group_by is present) -# Most databases expect them to match, but some -# choke in various ways. +# Most databases would be happy with whatever ends up +# here, but some choke in various ways. # -sub _grouped_count_select { - my ($self, $source, $rs_args) = @_; - return $rs_args->{group_by}; +sub _subq_count_select { + my ($self, $source, $rs_attrs) = @_; + return $rs_attrs->{group_by} if $rs_attrs->{group_by}; + + my @pcols = map { join '.', $rs_attrs->{alias}, $_ } ($source->primary_columns); + return @pcols ? \@pcols : [ 1 ]; } + sub source_bind_attributes { my ($self, $source) = @_; - + my $bind_attributes; foreach my $column ($source->columns) { - + my $data_type = $source->column_info($column)->{data_type} || ''; $bind_attributes->{$column} = $self->bind_attribute_by_data_type($data_type) if $data_type; diff --git a/lib/DBIx/Class/Storage/DBI/mysql.pm b/lib/DBIx/Class/Storage/DBI/mysql.pm index 221548a..53b8e16 100644 --- a/lib/DBIx/Class/Storage/DBI/mysql.pm +++ b/lib/DBIx/Class/Storage/DBI/mysql.pm @@ -64,10 +64,10 @@ sub _subq_update_delete { # primary keys of the main table in the inner query. This hopefully still # hits the indexes and keeps mysql happy. # (mysql does not care if the SELECT and the GROUP BY match) -sub _grouped_count_select { - my ($self, $source, $rs_args) = @_; - my @pcols = map { join '.', $rs_args->{alias}, $_ } ($source->primary_columns); - return @pcols ? \@pcols : $rs_args->{group_by}; +sub _subq_count_select { + my ($self, $source, $rs_attrs) = @_; + my @pcols = map { join '.', $rs_attrs->{alias}, $_ } ($source->primary_columns); + return @pcols ? \@pcols : [ 1 ]; } 1;