Sql update takes 4 days for 10 million records - oracle

Question

I want to update a database table which has over 10 million records from a temporary table.
But my update query executes more than 4 days.
1.) I have already created an index for update search criteria for
tax_ledger_item_tab. index creatred on party_type, identity, company.
My search criteria are on party_type, identity, company, delivery_type_id
as the following given query, those columns are not keys in the table.
I believe that I cant add delivery_type_id for the index as it will
update by the query, if I add that into index performance will be worst.
2.) temporary table identity_invoice_info_cfv will also returns 70,000 records
also.
So far I believe my update execution plan cost will be like around 70000*10 million records.
How can I get performance enhancement with following update query? I only want to update delivery_type_id, fetched columns only.
DECLARE
CURSOR get_records IS
SELECT i.COMPANY, i.IDENTITY, i.CF$_DELIVERY_TYPE
FROM identity_invoice_info_cfv i
WHERE i.PARTY_TYPE_DB = 'CUSTOMER';
BEGIN
FOR rec_ IN get_records LOOP
dbms_output.put_line (sysdate );
UPDATE tax_ledger_item_tab t
SET t.delivery_type_id = rec_.CF$_DELIVERY_TYPE, t.fetched = 'TRUE'
WHERE t.party_type = 'CUSTOMER'
AND t.identity = rec_.IDENTITY
AND t.company = rec_.COMPANY
AND t.delivery_type_id IS NULL;
COMMIT;
END LOOP;
END;

Answer 1

Use a MERGE statement:
Oracle Setup:
CREATE TABLE identity_invoice_info_cfv ( COMPANY, IDENTITY, CF$_DELIVERY_TYPE, PARTY_TYPE_DB ) AS
SELECT 'A', 123, 456, 'CUSTOMER' FROM DUAL;
CREATE TABLE tax_ledger_item_tab ( identity, company, party_type, delivery_type_id, fetched ) AS
SELECT 123, 'A', 'CUSTOMER', CAST( NULL AS NUMBER ), 'FALSE' FROM DUAL;
Merge:
MERGE INTO tax_ledger_item_tab t
USING identity_invoice_info_cfv i
ON (
t.identity = i.identity
AND t.company = i.COMPANY
AND t.party_type = 'CUSTOMER'
AND i.PARTY_TYPE_DB = 'CUSTOMER'
)
WHEN MATCHED THEN
UPDATE
SET delivery_type_id = i.CF$_DELIVERY_TYPE,
fetched = 'TRUE'
WHERE t.delivery_type_id IS NULL;
Query:
SELECT * FROM tax_ledger_item_tab;
Output:
IDENTITY | COMPANY | PARTY_TYPE | DELIVERY_TYPE_ID | FETCHED
-------: | :------ | :--------- | ---------------: | :------
123 | A | CUSTOMER | 456 | TRUE
db<>fiddle here

Answer 2

I hope you can achieve this using Merge Statement as well. Below is the code for the same. Please test from your side with some sample data and then proceed.
Merge into tax_ledger_item_tab t
using identity_invoice_info_cfv i
on (t.party_type ='CUSTOMER' and t.identity=i.IDENTITY
and t.company = i.COMPANY and i.PARTY_TYPE_DB = 'CUSTOMER')
when matched then
update set
t.delivery_type_id=i.CF$_DELIVERY_TYPE,
t.fetched = 'TRUE'
where t.delivery_type_id IS NULL;
commit;