SQL/MX 2.x Query Guide (G06.24+, H06.03+)

Operators and Operator Groups
HP NonStop SQL/MX Query Guide—523728-003
7-25
LEFT_ORDERED_HASH_JOIN Operator
The LEFT_NESTED_JOIN has two child nodes. The description field for this operator
contains:
The example of the LEFT_NESTED_JOIN operator is based on:
SELECT a.ten, MAX(a.unique2)
FROM abase a LEFT JOIN bbase b ON a.unique2=b.unique3
WHERE a.onepercent = 90 by a.ten FOR READ UNCOMMITTED ACCESS;
3 6 7 left_nested_join
join_type: left
join_method: nested
parallel_join_type: 2
LEFT_ORDERED_HASH_JOIN Operator
Join Group
The LEFT_ORDERED_HASH_JOIN operator returns an unmatched outer row even
when it does not find a match in the inner table. Null values are supplied for the
missing inner rows. The LEFT_ORDERED_HASH_JOIN operator differs from the
LEFT_HYBRID_HASH_JOIN in that it preserves the order of the outer table and does
not overflow to disk. In addition, the reuse feature enables reuse of the hash table for
subsequent requests within the same query. Choose this operator when you need to
preserve the order of the outer table or if you can benefit from the reuse feature. It
should be chosen only if the inner table is small enough to fit in memory.
The LEFT_ORDERED_HASH_JOIN operator has two child nodes. The description
field for this operator contains:
Token Followed by ... Data Type
join_type Inner, left, natural, inner semi,
or inner anti-semi-join
text
join_method Name of join method text
join_predicate Expression of the join
predicates
expr(text)
parallel_join_type Type1 or Type2, depending on
parallel join algorithm
text
selection_predicates Expression of the selection
predicates
expr(text)
Token Followed by ... Data Type
hash_join_predicate Expression of the join
predicates
expr(text)
join_type Inner, left, natural, inner semi,
or inner anti-semi-join
text
join_method Name of join method text