Question

I am trying to optimize an Oracle query. Right now it runs pretty slow since the table has ~1M records. I have two tables, the item_location table, and the tariffs table. An item_location record has a dual key, the item_no and item_loc. The tariffs records are stored with a key tariff_code which is a random three-digit identifier, with fields import_tariff and export_tariff. The item_tariff_code is the foreign key for the item’s tariffs record.

Here is an SQLFiddle for simplicity.

I am trying to find the item_no with locations that have export_tariff‘s that match two values inclusive.

For example, if I want to find items with export_tariff equal to both "1111111111" and "2222222222", it would return "12345" because these records were in the database:

  item_no  |  item_loc  |  export_tariff
----------------------------------------
  12345    |  B1        |  1111111111
  12345    |  B2        |  2222222222

But it shouldn’t find "67890" because of this record:

  item_no  |  item_loc  |  export_tariff
----------------------------------------
  67890    |  B1        |  1111111111

Since it doesn’t have export_tariff "2222222222".

I’ve added the query I’ve been using so far in the SQLFiddle.

Answer 1

If you cannot use temp tables, Oracle has the WITH clause that can be used in pretty much the same way:

WITH t as (SELECT tariff_code FROM tariffs WHERE 
    (export_tariff LIKE '3916906000%' OR export_tariff LIKE '39191080%'))
SELECT t1.item_no FROM
(SELECT * FROM item_location il, t WHERE il.item_tariff_code = t.tariff_code) t1,
(SELECT * FROM item_location il, t WHERE il.item_tariff_code = t.tariff_code) t2
WHERE t1.item_no = t2.item_no AND t1.item_tariff_code <> t2.item_tariff_code

Thanks for SQLFiddle by the way, it’s a great site.

PS: I can’t see how to avoid the scanning of the item_location table twice, because you really have to do the join on item_no. If you want to get that out of the way quickly, you can turn around the order of execution with a query like this:

WITH il AS (
  SELECT
    il1.item_no,
    il1.item_tariff_code AS tc1,
    il2.item_tariff_code AS tc2
  FROM item_location il1
  JOIN item_location il2
    ON il1.item_no = il2.item_no AND
       il1.item_loc <> il2.item_loc)
SELECT item_no FROM il
JOIN tariffs t1
  ON il.tc1 = t1.tariff_code
JOIN tariffs t2
  ON il.tc2 = t2.tariff_code
WHERE
  t1.export_tariff LIKE '3916906000%' AND
  t2.export_tariff LIKE '39191080%'

See it at SQLFiddle