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

SQL/MX Operators
HP NonStop SQL/MX Release 3.2 Query Guide—663851-002
7-59
PROBE_CACHE Operator
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).
ROOT Operator
Root Group
The ROOT operator is the root, or the top node, of an execution plan and describes the
SQL query. The operator for a ROOT is always ROOT.
The ROOT operator has one child. The description field for this operator contains the
following:
Token Followed by ... Data Type
statement Original SQL statement text
select_list Expression of the SELECT list columns expr(text)
input_variables Expression containing list of input variables
(params)
expr(text)
order_by Expression containing list of sort keys expr(text)
must_match When CONTROL QUERY SHAPE is used,
textual description of forced query tree ()
expr(text)
update_col The update column specification of an
updatable cursor declaration
expr(text)
olt_optimization Indicates whether an optimization for short,
simple operations is used. The value used is
returned if this optimization is used.
text
TP663851.fm Page 59 Thursday, August 2, 2012 4:47 PM