AidanLee has asked for the wisdom of the Perl Monks concerning the following question:
Hi all,
I've got an efficiency/comprehensiveness question. I've got a list of sql tables, and a double-keyed hash (thanks btrott) which contains relationships between those tables. So here is the code that I've currently got to search/record that the relationships exist:
#Anonymous block for scoping { my( @linked_tables,@unlinked_tables) = (); #----------------------------------------------------------------- +------------------------------------ sub _get_table_relations { my( $self,$tables,$conditions ) = @_; #prep lists @unlinked_tables = keys %$tables; @linked_tables = (); my @tables_nolinks = (); #no relations to be found if there's only one table return if scalar( @unlinked_tables ) <= 1; # try to find a link for each of the supplied tables while( my $table = shift @unlinked_tables ) { next if grep { $table eq $_ } @linked_tables; push @tables_nolinks, $table unless $self->_table_relation +_helper($table,$conditions); } csWarn(class=>csErrorClass('CODE_PARAMS'),severity=>csErrorSca +le('MODERATE'), message=>'Could not find relations certain tables in th +is view.', debug=>"tables without relations:".join(',',@tables_nol +inks) ) if scalar( @tables_nolinks ); return 1; } #----------------------------------------------------------------- +------------------------------------ sub _table_relation_helper { my ($self,$table,$conditions) = @_; foreach my $table2 ( @linked_tables, @unlinked_tables ) { # a link exists if( exists $self->{_links}{$table,$table2} ) { #store the conditions of our found relationship with o +ur other conditions push @{ $conditions->{axioms} }, ( $self->{_links}{ +$table,$table2}{op} eq $conditions->{op} and ( $conditions->{op} eq ' +and' or $conditions->{op} eq 'or' )) ? @{ $self->{_ +links}{$table,$table2}{axioms} } : { %{ $self-> +{_links}{$table,$table2} } }; #first check to see if $table2 needs linking foreach my $i ( 0 .. $#unlinked_tables ) { if( $unlinked_tables[$i] eq $table2 ) { splice(@unlinked_tables,$i,1); $self->_table_relation_helper($table2,$conditi +ons) unless $table2 =~ /\s/; last; #short circuit the foreach } } #then add $table to $linked_tables push @linked_tables, $table; return 1; #short circuit } } return 0; } }
I've had to go back and add to this a couple of times as i've realized I left out certain scenarios where a relationship existed but the code couldn't find it, or where I wound up with two unjoined maps of tables when there should only be one map. So at this point I'm wondering if
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Re: Efficiency in Mapping Relationships
by runrig (Abbot) on Jul 23, 2001 at 22:44 UTC |