Data commit

Task/Hash-join/Perl/hash-join.pl

@@ -0,0 +1,30 @@
+use Data::Dumper qw(Dumper);
+
+sub hashJoin {
+    my ($table1, $index1, $table2, $index2) = @_;
+    my %h;
+    # hash phase
+    foreach my $s (@$table1) {
+	push @{ $h{$s->[$index1]} }, $s;
+    }
+    # join phase
+    map { my $r = $_;
+	  map [$_, $r], @{ $h{$r->[$index2]} }
+    } @$table2;
+}
+
+@table1 = ([27, "Jonah"],
+           [18, "Alan"],
+           [28, "Glory"],
+           [18, "Popeye"],
+           [28, "Alan"]);
+@table2 = (["Jonah", "Whales"],
+           ["Jonah", "Spiders"],
+           ["Alan", "Ghosts"],
+           ["Alan", "Zombies"],
+           ["Glory", "Buffy"]);
+
+$Data::Dumper::Indent = 0;
+foreach my $row (hashJoin(\@table1, 1, \@table2, 0)) {
+    print Dumper($row), "\n";
+}