my @unwanted = qw( schema log );

##</code><code>##

my %unwanted = map { $_ => 1 } @unwanted;

my @wanted = grep !$unwanted{ $_ }, keys %hash;
my %subhash = %hash{ @wanted };

do_something( \%sub_hash );

##</code><code>##

my %subhash = %hash;
delete @subhash{ @unwanted };

do_something( \%sub_hash );

##</code><code>##

delete local @hash{ @unwanted };

do_something( \%hash );