SQL/MX 2.x Reference Manual (H06.10+, J06.03+)

SQL/MX Statements
HP NonStop SQL/MX Reference Manual—544517-008
2-145
Considerations for EXPLAIN
When numbers are displayed as 0.01 for OPTIONS 'n' (or 0.0001 for OPTIONS
'e'), the numbers have likely been rounded up. However, if the numbers are zero, the
display shows “0”.
When trailing decimal digits are zero, they are dropped. For example, 6.4200 will be
displayed as 6.42 and 5.0 will be displayed as 5, without a decimal point.
Machine-readable [OPTIONS 'm'] Considerations
The machine-readable option provides an output in the format that can be read only by
machines but is suitable for programs.Table 2-2 lists the fields of the OPTIONS 'm'
output.
Table 2-2. Fields of OPTIONS 'm' Output
Column name Data Type Description
MODULE NAME CHAR (60) Reserved for future use.
STATEMENT NAME CHAR (60) Statement name; truncated on the right if
longer than 60 characters.
PLAN_ID INT Unique system-generated plan ID
automatically assigned by SQL; generated at
compile time.
SEQ_NUM CHAR (30) Sequence number of the current operator in
the operator tree; indicates the sequence in
which the operator tree is generated.
OPERATOR CHAR (30) Current operator type.
LEFT_CHILD_SEQ_NUM INT Sequence number for the first child operator of
the current operator; displays NULL if the
operator has no child operators.
RIGHT_CHILD_SEQ_NUM INT Sequence number for the second child
operator of the current operator; displays
NULL if the operator does not have a second
child.
TNAME CHAR (60) For operators in a scan group, the full name of
base table is truncated on the right if it is too
long for the column. If the correlation name
differs from the table name put the correlation
name first and then table name in
parentheses.
CARDINALITY REAL Estimated number of rows that are returned by
the current operator.
OPERATOR_COST REAL Estimated cost associated with the current
operator to execute the operator.