SQL/MX 3.2 Query Guide (H06.25+, J06.14+)

SQL/MX Operators
HP NonStop SQL/MX Release 3.2 Query Guide—663851-002
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
the following:
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
TP663851.fm Page 62 Thursday, August 2, 2012 4:47 PM