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

SQL/MX Operators
HP NonStop SQL/MX Query Guide—640323-001
7-56
PROBE_CACHE Operator
The following is an example of the PARTITION_ACCESS operator:
prepare TestQuery17 from
select T03.char_100
from PTAB03 T03
where T03.char_100 =
(Select min(T00.char_10)
from PTAB00 T00
);
DESCRIPTION
fragment_id ............ 2
parent_frag ............ 0
fragment_type .......... dp2
buffer_size ............ 31,000
record_length .......... 11
space_usage ............ 19:8:8:40
eid_space_computation on
begin_key_preds_(incl)
(DETCAT.DETSCH.PTAB00.SINT32_UNIQ =
<min>)
end_key_preds_(incl) ... (DETCAT.DETSCH.PTAB00.SINT32_UNIQ =
<max>)
begin_part_no_expr ..... \:_sys_hostVarPAPartNo_1606919584
end_part_no_expr ......... \:_sys_hostVarPAPartNo_1606919584
PROBE_CACHE Operator
This operator appears above the right child of a nested join and is an optimization to
reduce the work done by the right child. The operator has a mechanism to cache
results of a probe (request) into the inner child from the outer child. If the probe
repeats, the cached result is used to improve the performance.
The DESCRIPTION column of the explain function will contain token-value pairs to
name the probe columns sent to the inner table, the sizes of the cache and inner table
buffer (called num_inner_tuples).
child_partitioning_function Type of bottom partitioning and contains
summary information about the parallel
plan.
text
begin_part_selection_expr Expression used by SPLIT_TOP or
PARTITION_ACCESS to compute the
begin_part_no_expr.
expr(text)
end_part_selection_expr Expression used by SPLIT_TOP or
PARTITION_ACCESS to text compute
the end_part_no_expr.
expr(text)
Token Followed by ... Data Type