Hi nysus, thank you very much for the response. Exactly what I was looking for!

New code is here.

#!/usr/bin/perl
# Compare two schemas or tables for names, types and length.

use v5.10;
no strict;

my %tables1_lookup=();
my %tables2_lookup=();

my %DS1=( PERL => [
            {TABLES=>{ TABSCHEMA=>"VARCHAR(128)", TABNAME=>"VARCHAR(12
+8)", }}, # Tables and Columns are names of the tables.
            {COLUMNS=>{ TABSCHEMA=>"VARCHAR(128)", TABNAME=>"VARCHAR(1
+28)", COLNAME=>"VARCHAR(128)", PARTKEYSEQ=>"SMALLINT", }}
               ]
      );

my %DS2=( PERL => [
            {TABLES=>{ TABSCHEMA=>"VARCHAR(256)", TABNAME=>"VARCHAR(12
+8)", }}, # Tables and Columns are names of the tables.
            {COLUMNS=>{ TABSCHEMA=>"VARCHAR(256)", TABNAME=>"VARCHAR(1
+28)", COLNAME=>"VARCHAR(128)", PARTKEYSEQ=>"SMALLINT", }}
               ]
      );

foreach my $schema1 (keys %DS1)
   {
   if (exists $DS2{$schema1})
      {
      say "Schema $schema1 exist in target.";
      } else {
      die "Schema $schema1 does not exist in target.";
      }


   # Build look up hashes with tables list for schema one from DS1.
   foreach my $tabhash1_ref (@{$DS1{$schema1}})
      {
      foreach my $tables1_name (keys %{$tabhash1_ref})
         {
         $tables1_lookup{$tables1_name}=1;
         }
      }

    # Build look up hashes with tables list for schema two from DS2.
    foreach my $tabhash2_ref (@{$DS2{$schema1}})
      {
      foreach my $tables2_name (keys %{$tabhash2_ref})
         {
         $tables2_lookup{$tables2_name}=1;
         }
      }

    foreach my $tables1_name(keys %tables1_lookup)
       {
       if (! exists $tables2_lookup{$tables1_name})
          {
          say "$tables1_name table does not exists in target schema 2.
+"
          }
       else
          {
          say "$tables1_name table exists in target schema 2"
          }
       }
   }
[download]

Output is here:

Schema PERL exist in target.
COLUMNS table exists in target schema 2
TABLES table exists in target schema 2
[download]

Looks like I need to learn how to use hashes as lookup tables :-)