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

SQL/MX Functions and Expressions
HP NonStop SQL/MX Reference Manual—544517-008
9-59
Examples of EXPLAIN
Operators are grouped together for purposes of display within the EXPLAIN statement.
For more information about the use of the result table of the EXPLAIN function, see the
SQL/MX Query Guide.
Examples of EXPLAIN
•
Use the EXPLAIN statement to construct and display all columns in the result table
of the EXPLAIN function for the specified prepared statement:
prepare xx from
select * from part where p_partkey = (select max(ps_partkey)
from partsupp);
explain options 'f' xx;
SUBSET_DELETE
SUBSET_UPDATE
TRANSPOSE
TUPLE_FLOW
TUPLELIST
UNIQUE_DELETE
UNIQUE_UPDATE
UNPACK
VALUES
DAM subset
DAM subset
Data mining
Join
Tuple
DAM unique
DAM unique
Rowset
Tuple
LEFT_CHILD_
SEQ_NUM
INT Sequence number for the first child operator of the current
node (or operator); null if node has no child operators.
RIGHT_CHILD_
SEQ_NUM
INT Sequence number for the second child operator of the
current node (or operator); null if node does not have a
second child.
TNAME CHAR(60) For operators in scan group, full name of base table,
truncated on the right if too long for column. If correlation
name differs from table name, simple correlation name first
and then table name in parentheses.
CARDINALITY REAL Estimated number of rows that will be returned by the
current node.
OPERATOR_
COST
REAL Estimated cost associated with the current node to execute
the operator.
TOTAL_COST REAL Estimated cost associated with the current node to execute
the operator, including the cost of all subtrees in the
operator tree.
DETAIL_COST VARCHAR
(200)
Tokenized cost vector.
DESCRIPTION VARCHAR
(3000)
Additional information about the operation in the form of a
stream of token pairs.
Column Name Data Type Description