DB2 UDB for z/OS Version 8 Performance Topics - IBM Redbooks

Column Type Content
--------58 Columns
Format-------Version 8 ----2003-
D.1.2 DSN_STATEMNT_TABLE
EXPLAIN estimates the cost of executing an SQL SELECT, INSERT, UPDATE, or DELETE
statement. The output appears in a table called DSN_STATEMNT_TABLE. The columns of
this table and their contents are listed in Table D-3. For more information about statement
tables, see “Estimating a statement’s cost” on the DB2 UDB for z/OS Version 8 Administration
Guide, SC18-7413.
Table D-3 EXPLAIN enhancements in DSN_STATEMNT_TABLE
Column Name Type Content
QUERYNO INTEGER NOT NULL WITH
DEFAULT
-58 Column Format -Version 8 -Mar.
26, 2004-
A number that identifies the statement
being explained.
APPLNAME CHAR(8) NOT NULL WITH DEFAULT The name of the application plan for
the row, or blank.
PROGNAME VARCHAR (128) NOT NULL WITH
DEFAULT
COLLID VARCHAR (128) NOT NULL WITH
DEFAULT
GROUP_MEMBER CHAR (8) NOT NULL WITH
DEFAULT
The name of the program or package
containing the statement being
explained, or blank.
The collection ID for the package.
The member name of the DB2 that
executed EXPLAIN, or blank.
EXPLAIN_TIME TIMESTAMP The time at which the statement is
processed.
STMT_TYPE CHAR (6) NOT NULL WITH
DEFAULT
COST_CATEGORY CHAR (1) NOT NULL WITH
DEFAULT
PROCMS INTEGER NOT NULL WITH
DEFAULT
PROCSU INTEGER NOT NULL WITH
DEFAULT
REASON VARCHAR (256) NOT NULL WITH
DEFAULT
STMT_ENCODE CHAR (1) NOT NULL WITH
DEFAULT
The type of statement being
explained. SELECT,
UPDATE,INSERT, or UPDATE...
Indicates if DB2 was forced to use
default values when making its
estimates (B) or used statistics (A).
The estimated processor cost, in
milliseconds, for the SQL statement.
The estimated processor cost, in
service units, for the SQL statement.
A string that indicates the reasons for
putting an estimate into cost category
B.
Encoding scheme of the statement.
A = ASCII
E = EBCDIC
U = Unicode
Appendix D. EXPLAIN and its tables 415