SQL/MX 2.x Query Guide (H06.04+, J06.03+)

SQL/MX Operators
HP NonStop SQL/MX Query Guide—540437-005
7-35
LEFT_MERGE_JOIN Operator
returned, and the data from the right table is set to null. See MERGE_JOIN Operator
on page 7-40.
The LEFT_MERGE_JOIN operator has two child nodes. The description field for this
operator contains:
The example of the LEFT_MERGE_JOIN operator is based on:
Control Query Default nested_joins 'off';
Control Query Default hash_joins 'off';
prepare TestQuery37b from
SELECT *
FROM customer LEFT JOIN nation ON c_nationkey = n_nationkey
WHERE c_custkey > 1000 AND c_custkey < 1010
ORDER BY c_custkey;
DESCRIPTION
fragment_id ............ 0
parent_frag ............ (none)
fragment_type .......... master
join_type .............. left
join_method ............ merge
merge_join_predicate ... (DETCAT.DETSCH.CX1.C_NATIONKEY =
DETCAT.DETSCH.NATION.N_NATIONKEY)
Token Followed by ... Data Type
fragment_id A sequential number assigned to the
fragment. 0 is always the master executor and
1 is reserved for the EXPLAIN plan. Numbers
2 to n will be ESP or DAM fragments.
integer
parent_frag The fragment_id for the parent fragment of the
current fragment. The value is (none) for the
master executor.
integer
fragment_type Master, ESP, or DP2 text
join_type Inner, left, natural, inner semi, or inner anti-
semi-join
text
join_method Name of join method: merge text
merge_join_predicate Expression of the join predicate. expr(text)
parallel_join_type Type1 or Type2, depending on parallel join
algorithm.
text
selection_predicates Expression of the WHERE clause. expr(text)