| java.lang.Object
 org.axiondb.engine.rowiterators.BaseRowIterator
org.axiondb.engine.rowiterators.AbstractJoinedRowIterator
org.axiondb.engine.rowiterators.IndexNestedLoopJoinedRowIterator
| IndexNestedLoopJoinedRowIterator | | public class IndexNestedLoopJoinedRowIterator extends AbstractJoinedRowIterator (Code) | | The Index Nested Loop Join or Augmented Nested Loop Join (ANL) is by far the most
common join method and is the classic Axion join method. An augmented nested loop join
is performed by doing a scan over the left subtree and for each row in it, performing
an index bracket scan on a portion of the right subtree. The right subtree is read as
many times as there are rows in the left subtree. To be a candidate for an ANL join,
the subtree pair for a join node must meet the following criteria:
There must be an index(es) defined on the join column(s) for the table in the
right subtree.
No other scan on that index has already been set.
When there is an index defined on the left subtree’s table instead of on the right, the
optimizer swaps the subtrees to make an ANL join possible. When neither subtree’s table
has an index defined on the join column, the optimizer creats a dynamic index on one of
the subtree.
version:
$Revision: 1.3 $ $Date: 2005/04/02 18:23:30 $
author:
Rodney Waldhoff
author:
Ahimanikya Satapathy |
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