About your problem,
You can make two qvd's only with the PKey Field, one with 17 million records and other with 30,000 records
and use this qvd in your select
After you dismiss this 30,000 from the 17 million qvd
WHERE NOT EXISTS (PK);
To the next day you will your base qvd equal 17 million - 30,000 records to start again.
Also, keep in mind that everything after "SQL" needs to be valid SQL and "where not exists (PKey) " is not, because I believe it expects a SQL subquery.
LOAD *; SQL SELECT * FROM "GL_Transactions".dbo."GL_Transactions" where not exists (PKey) ;
Mind you, I could be wrong, I'm not a SQL genius, just made this error a couple of times myself...