Can a query make use of an Index on concat column ?

Question

Hi sql gurus,
We will develope application on a database as below ( simplified ) :
create table invoice (doc_no varchar2(30), cust_code varchar2(10), amount number (12,2));
create table debit_memo (doc_code varchar2(6), doc_no varchar2(24), cust_code varchar2(10), amount number (12,2));
create table credit_memo (doc_code varchar2(6), doc_no varchar2(24), cust_code varchar2(10), amount number (12,2));
create view v_ar_transaction as
select doc_no, cust_code, amount from invoice
union
select doc_code||doc_no, cust_code, amount from debit_memo
union
select doc_code||doc_no, cust_code, amount from credit_memo
The question is :
If I have query like this :
select * from v_ar_transaction where doc_no = :pdoc_no
Can it use the index built on the tables ?
What kind of index that will help the above query to be efficient ?
Thank you for your help,
xtanto

Answer 1

create view v_ar_transaction as
select doc_no, cust_code, amount from invoice
union
select doc_code||doc_no, cust_code, amount from
debit_memo
union
select doc_code||doc_no, cust_code, amount from
credit_memo
he question is :
If I have query like this :
select * from v_ar_transaction where doc_no =
:pdoc_no
an it use the index built on the tables ?
What kind of index that will help the above query to
be efficient ?I'd try:
doc_no for invoice
function based index doc_code||doc_no for debit_memo and credit_memo
As a side note - do you really need UNION or UNION ALL?
Isn't important where the transaction comes from?
Gints Plivna
http://www.gplivna.eu