SQL/MX 3.x Query Guide (H06.22+, J06.11+)

SQL/MX Operators
HP NonStop SQL/MX Query Guide—640323-001
7-52
ORDERED_UNION Operator
hash_join_predicate .... (DETCAT.DETSCH.ORDERS.O_ORDERKEY =
DETCAT.DETSCH.LX5.L_ORDERKEY)
ORDERED_UNION Operator
The ORDERED_UNION operator ensures that its left and right children work one at a
time. It first receives rows from its left child. It then enables the right child to work. In
effect, for the same request, ORDERED_UNION operator produces rows from left child
followed by rows from right child.
The description field for this operator contains:
The following is an example of the ORDERED_UNION operator:
create table table_a
(col1 char(5) NOT NULL NOT DROPPABLE
, col2 int NOT NULL NOT DROPPABLE
, col3 smallint
, CONSTRAINT table_a_PRIMARY_KEY PRIMARY KEY (col1 ASC, col2
ASC) NOT DROPPABLE
);
create table table_b
(col1 char(5) NOT NULL NOT DROPPABLE
, col2 int NOT NULL NOT DROPPABLE
, col3 smallint
, owner_count int
, CONSTRAINT table_b_PRIMARY_KEY PRIMARY KEY (col1 ASC, col2
ASC) NOT DROPPABLE
);
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 of the current
fragment. The value is (none) for the master
executor.
integer
fragment_type Master, ESP, or DP2. text
sort_order Sort order of the result of the union. text
merge_expression Expression used to determine which child
operator to read from next—read from left if true
and read from right if false.
expr(text)
union_type Merge, physical or unspecified. text
condExpr Expression used for conditional union. Occurs
with IF statement in compound statements.
expr(text)
trigExceptExpr Expression used for trigger exceptions. expr(text)