| Pl. clear my douts of nested loop join. [message #65542] |
Thu, 21 October 2004 01:11  |
BhavinShah
Messages: 105
Registered: February 2004
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Senior Member |
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Dear frends,
I have some dout in nested loop join pl. clarify me.
SELECT a.unit_price * a.quantity
FROM order_items a,orders b
WHERE b.customer_id = :b1
AND a.order_id = b.order_id
Plan
-------------------------------------------------
SELECT STATEMENT
NESTED LOOPS
TABLE ACCESS BY INDEX ROWID ORDERS
INDEX RANGE SCAN CUSTOMER_ID
TABLE ACCESS BY INDEX ROWID ORDER_ITEMS
INDEX RANGE SCAN ORDER_ID
In this case Order table is outer table and order_items table is inner table.
Actually How the Oracle Execute this plan..My mean to say is first it will keep block of first
row of outer table in buffer cache and then all rows of inner table in buffer cache.
Is inner table is scanned every time for every row of outer table ??
Pl.clear my douts.
Thax in adv.
Bhavin Shah
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