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

SQL/MX Operators
HP NonStop SQL/MX Query Guide—640323-001
7-60
SAMPLE_FILE_SCAN Operator
The following is an example of the SAMPLE_FILE_SCAN operator:
PREPARE TestQuery22 FROM
select * from tt22 sample random 10 percent;
DESCRIPTION
fragment_id ............ 2
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
key_columns Columns used as the primary key. expr(text)
executor_predicates Any predicate expression that is not a key
predicate evaluated by the executor in DAM.
expr(text)
mdam_disjunct Disjunct key predicates used by MDAM expr(text)
part_key_predicate Predicate expression specified on partitioning
key. It is displayed only if partitioning key
differs from clustering key.
expr(text)
begin_key Expression of the begin key predicate. expr(text)
end_key Expression of the end key predicate. expr(text)
key_type Simple or MDAM. text