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

SQL/MX Operators
HP NonStop SQL/MX Query Guide—640323-001
7-9
CURSOR_UPDATE Operator
CURSOR_UPDATE Operator
DAM Unique Group
The CURSOR_UPDATE operator describes a portion of an execution plan that works
on one row only. The CURSOR_UPDATE operation is performed by first retrieving
rows from the table and then updating each row that is required. This operation differs
from SUBSET_UPDATE, in which the read and update are performed in a combined
operation.
The CURSOR_UPDATE operator has no child nodes. The description field for this
operator contains:
The following is an example of the CURSOR_UPDATE operator:
UPDATE table_b SET owner_count = (
SELECT count(*) FROM table_a
WHERE (table_b.col1,table_b.col2)=
(table_a.col1,table_a.col2)
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. Its value is used or
not used.
text
olt_opt_lean Indicates for short, simple operations whether a
further optimization that reduces the physical
size of the plan is used. Its value is used or
not used.
text
iud_type Type of update followed by table or index
name.
expr(text)
new_rec_expr Computation of the row to be updated. expr(text)
begin_key Expression of the begin key predicate. expr(text)
index_begin_key Expression of the begin key predicates on
index.
expr(text)
part_key_predicate Predicate expression specified on partitioning
key. It is displayed only if partitioning key differs
from clustering key.
expr(text)
check_constraint Check constrains in the update table. expr(text)