3 files changed, 41 insertions, 0 deletions
diff --git a/Bugzilla/DB/Mysql.pm b/Bugzilla/DB/Mysql.pm
index 8a64d3646..fdb475078 100644
--- a/Bugzilla/DB/Mysql.pm
+++ b/Bugzilla/DB/Mysql.pm
@@ -48,6 +48,8 @@ use Bugzilla::Util;
 use Bugzilla::Error;
 use Bugzilla::DB::Schema::Mysql;
 
+use List::Util qw(max);
+
 # This module extends the DB interface via inheritance
 use base qw(Bugzilla::DB);
 
@@ -204,6 +206,30 @@ sub sql_group_by {
     return "GROUP BY $needed_columns";
 }
 
+sub bz_explain {
+    my ($self, $sql) = @_;
+    my $sth  = $self->prepare("EXPLAIN $sql");
+    $sth->execute();
+    my $columns = $sth->{'NAME'};
+    my $lengths = $sth->{'mysql_max_length'};
+    my $format_string = '|';
+    my $i = 0;
+    foreach my $column (@$columns) {
+        # Sometimes the column name is longer than the contents.
+        my $length = max($lengths->[$i], length($column));
+        $format_string .= ' %-' . $length . 's |';
+        $i++;
+    }
+
+    my $first_row = sprintf($format_string, @$columns);
+    my @explain_rows = ($first_row, '-' x length($first_row));
+    while (my $row = $sth->fetchrow_arrayref) {
+        my @fixed = map { defined $_ ? $_ : 'NULL' } @$row;
+        push(@explain_rows, sprintf($format_string, @fixed));
+    }
+
+    return join("\n", @explain_rows);
+}
 
 sub _bz_get_initial_schema {
     my ($self) = @_;
diff --git a/Bugzilla/DB/Oracle.pm b/Bugzilla/DB/Oracle.pm
index 56d9d3fbf..341818a5c 100644
--- a/Bugzilla/DB/Oracle.pm
+++ b/Bugzilla/DB/Oracle.pm
@@ -104,6 +104,15 @@ sub bz_check_regexp {
         { value => $pattern, dberror => $self->errstr });
 }
 
+sub bz_explain { 
+     my ($self, $sql) = @_; 
+     my $sth = $self->prepare("EXPLAIN PLAN FOR $sql"); 
+     $sth->execute();
+     my $explain = $self->selectcol_arrayref(
+         "SELECT PLAN_TABLE_OUTPUT FROM TABLE(DBMS_XPLAN.DISPLAY)");
+     return join("\n", @$explain); 
+} 
+
 sub sql_regexp {
     my ($self, $expr, $pattern, $nocheck) = @_;
 
diff --git a/Bugzilla/DB/Pg.pm b/Bugzilla/DB/Pg.pm
index a6a2e3281..d06decaa3 100644
--- a/Bugzilla/DB/Pg.pm
+++ b/Bugzilla/DB/Pg.pm
@@ -171,6 +171,12 @@ sub bz_sequence_exists {
     return $exists || 0;
 }
 
+sub bz_explain {
+    my ($self, $sql) = @_;
+    my $explain = $self->selectcol_arrayref("EXPLAIN ANALYZE $sql");
+    return join("\n", @$explain);
+}
+
 #####################################################################
 # Custom Database Setup
 #####################################################################