SQL/MX 3.1 Query Guide (H06.23+, J06.12+)

SQL/MX Operators
HP NonStop SQL/MX Release 3.1 Query Guide—663851-001
7-62
SAMPLE_FILE_SCAN Operator
case(if_then_else((0 <= 0), 0,
if_then_else((0 < 1), 1,
if_then_else((1 > 0), ((0 assign
(1 - 100)) block 1 ), 0)))))
SAMPLE_FILE_SCAN Operator
The SAMPLE_FILE_SCAN operator occurs as a result of a sample clause in a query,
where it is possible to read randomly after satisfying the conditions mentioned in the
query. This operator has no child node. The description field for this operator contains:
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,
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
scan_type FILE_SCAN followed by table name. text
scan_direction Direction in which table is scanned: forward or
reverse.
text
lock_mode The lock mode specified: shared, exclusive,
not specified (defaulted to lock cursor), or
unknown.
text
access_mode The access specified: read uncommitted, skip
conflict, read committed, stable, serializable,
mx serializable, not specified (defaulted to
read committed), or unknown.
text
columns_retrieved Estimation of the number of columns to be
returned.
integer
fast_scan Indication of whether an optimization for a
simple scan operation is used. The value
used is returned if this optimization is used.
text
fast_replydata_move Indication of whether an optimization for
returning data from DAM is used. The value
used is returned if this optimization is used.
text
TP663851.fm Page 62 Monday, October 17, 2011 11:48 AM