Oracle has a great feature, called global temporary table. For details see https://www.oracletutorial.com/oracle-basics/oracle-global-temporary-table/. You can create your temporary table(s) only once, they will be there for good. These tables can be populated with INSERT INTO SELECT statements (see https://www.oracletutorial.com/oracle-basics/oracle-insert-into-select/) in the beginning of the transaction. Then they can be modified by UPDATE and/or MERGE (see https://www.oracletutorial.com/oracle-basics/oracle-merge/). When data looks okay in the global temp table, it can be written into its final location by INSERT or MERGE. Simple and straightforward.

Based on these features you probably can put together single perl script using module DBI (DBD::Oracle) and all the steps can be done with only a few $dbh->do(sqlstatement).

Regards