If you want the schema information to hash it, the most generic way would be the catalog methods of DBI:

my $sth = $dbh->table_info();
my $tables = $sth->fetchall_arrayref();
print Dumper @$tables;
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Hi Corion, Hashing here means not taking values to a hash, what I meant was to generate a hash/checksum(by using hashing algo like sha1,sha256,md5, etc) value in each table definition in each schema. As an example below is the test file i am generating in Oracle database. In there, I have created temporary table and generate hash values and inserted into a temporary table. #SCHEMA_NAME,OBJECT_TYPE,TABLE_NAME,HASH_VALUE,CREATED_TIME TEST_USER,TABLE,USER_DETAILS,30D841C3EEA693D1436D9B7978903527F9D0DDB6,25-SEP-17

So that hashvalue

30D841C3EEA693D1436D9B7978903527F9D0DDB6

is the result of hashing the string "#SCHEMA_NAME,OBJECT_TYPE,TABLE_NAME,HASH_VALUE,CREATED_TIME TEST_USER,TABLE,USER_DETAILS" ?

Isn't that trivially done in postgres easily with Corion's retrieval values (or mine), and postgres' md5() function (or similar functions from perl, or pgcrypto) ? Where are you having problems?

Also, do you mean 'temporary' where you wrote 'temporal'? And why 'temporary', or 'temporal'?

I don't really see the problem. That oracle get_dll() just gets you the metadata. Every database can give you metadata.

An easy way in postgres is to use the views in schema information_schema. To see a list in psql:

   \dv information_schema.
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select 
    table_schema
  , table_name
  , data_type
from information_schema.columns
where table_schema = 'public'
  and table_name= 'pgbench_accounts'
order by ordinal_position;
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and use something like that to md5 (or another checksum), either as a whole or on a row-by-row basis, or both.