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

SQL/MX Operators
HP NonStop SQL/MX Query Guide—640323-001
7-70
SPLIT_TOP Operator
SPLIT_TOP Operator
Exchange Group
The SPLIT_TOP operator describes a portion of an execution plan for a file system
interface in which requests to DAM occur with some level of parallel processing. The
operator for a SPLIT_TOP operator is always SPLIT_TOP. For more information about
exchange operators, see Section 8, Parallelism.
The SPLIT_TOP operator has one child node. The description field for this operator
contains:
The following is an example of the SPLIT_TOP operator:
PREPARE TestQuery19 FROM
select cust_id, count(*) as order_count from orders
where order_date > (date '2001-01-12') group by cust_id order by
cust_id;
DESCRIPTION
fragment_id ............ 0
parent_frag ............ (none)
fragment_type .......... master
olt_optimization ....... not used
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
olt_optimization Indicates whether an optimization for short
and simple operations is used. Value is
used if this optimization is used. Its value is
used or not used.
text
parent_processes Number of ESPs containing this operator.
The value will be one if the parent is Master
Executor.
integer
child_processes Number of bottom partitions. integer
parent_partitioning_function Type of top partitioning and contains
summary information about the parallel
plan.
text
child_partitioning_function Indicates how the input data received by the
SPLT_TOP is organized.
text