DSN_FUNCTION_TABLE
The function table, DSN_FUNCTION_TABLE, contains descriptions of functions that are used in specified SQL statements.
Qualifiers
Your subsystem or data sharing group can contain multiple instances of these tables that are qualified by user ID. These tables are populated with statement cost information when you issue the EXPLAIN statement or bind. They are also populated when you specify EXPLAIN(YES) or EXPLAIN(ONLY) in a BIND or REBIND command. SQL optimization tools might also create EXPLAIN tables that are qualified by a user ID. You can find the SQL statement for creating an instance of these tables in member DSNTESC of the SDSNSAMP library.
Sample CREATE TABLE statement
You can find a sample CREATE TABLE statement for each EXPLAIN table in member DSNTESC of the prefix.SDSNSAMP library. You can call the ADMIN_EXPLAIN_MAINT stored procedure to create EXPLAIN tables, upgrade them to the format for the current Db2 release, or complete other maintenance tasks. See ADMIN_EXPLAIN_MAINT stored procedure for information about using the action input parameter to request each of these tasks.
Column descriptions
The following table describes the columns of DSN_FUNCTION_TABLE.
Column name | Data type | Description |
---|---|---|
QUERYNO | INTEGER NOT NULL WITH DEFAULT | A number that identifies the statement that is being explained. The origin of the value depends on the context of the row:
When the values of QUERYNO are based on the statement number in the source program, values that exceed 32767 are reported as 0. However, in certain rare cases, the value is not guaranteed to be unique. When the SQL statement is embedded in a compiled SQL function, native SQL procedure, or advanced trigger, if the QUERYNO clause is specified, its value is used by Db2. Otherwise Db2 assigns a number based on the line number of the SQL statement in the compiled SQL function, native SQL procedure, or advanced trigger. |
QBLOCKNO | INTEGER NOT NULL WITH DEFAULT | A number that identifies each query block within a query. The value of the numbers are not in any particular order, nor are they necessarily consecutive. |
APPLNAME | VARCHAR(24) NOT NULL WITH DEFAULT | The name of the application plan
for the row. Applies only to embedded EXPLAIN statements that are executed from a plan or to
statements that are explained when binding a plan. A blank indicates that the column is not
applicable. When the SQL statement is embedded in a compiled SQL function, native SQL procedure, or advanced trigger, this column is not used, and is blank. |
PROGNAME | VARCHAR(128) NOT NULL WITH DEFAULT | The name of the program or package
containing the statement being explained. Applies only to embedded EXPLAIN statements and to
statements explained as the result of binding a plan or package. A blank indicates that the column
is not applicable. When the SQL statement is embedded in a compiled SQL function or native SQL procedure, this column indicates the specific name of the compiled SQL function or native SQL procedure. When the SQL statement is embedded in an advanced trigger, this column contains the name of the trigger. |
COLLID | VARCHAR(128) NOT NULL WITH DEFAULT | The collection ID:
When the SQL statement is embedded in a compiled SQL function, native SQL procedure, or advanced trigger, this column indicates the schema name of the compiled SQL function, native SQL procedure, or advanced trigger. |
GROUP_MEMBER | VARCHAR(24) NOT NULL WITH DEFAULT | The member name of the Db2 that executed EXPLAIN. The column is blank if the Db2 subsystem was not in a data sharing environment when EXPLAIN was executed. |
EXPLAIN_TIME | TIMESTAMP NOT NULL WITH DEFAULT | The
time when the EXPLAIN information was captured:
|
SCHEMA_NAME | VARCHAR(128) NOT NULL WITH DEFAULT | The schema name of the function invoked in the explained statement. |
FUNCTION_NAME | VARCHAR(128) NOT NULL WITH DEFAULT | The name of the function invoked in the explained statement. |
SPEC_FUNC_NAME | VARCHAR(128) NOT NULL WITH DEFAULT | The specific name of the function invoked in the explained statement. |
FUNCTION_TYPE | CHAR(2) NOT NULL WITH DEFAULT | The type of function invoked in the explained
statement. Possible values are:
|
VIEW_CREATOR | VARCHAR(128) NOT NULL WITH DEFAULT | If the function specified in the FUNCTION_NAME column is referenced in a view definition, the creator of the view. Otherwise, blank. |
VIEW_NAME | VARCHAR(128) NOT NULL WITH DEFAULT | If the function specified in the FUNCTION_NAME column is referenced in a view definition, the name of the view. Otherwise, blank. |
PATH | VARCHAR(2048) NOT NULL WITH DEFAULT | The value of the SQL path that was used to resolve the schema name of the function. |
FUNCTION_TEXT | VARCHAR(1500) NOT NULL WITH DEFAULT | The text of the function reference (the function name and parameters). If the function reference is over 100 bytes, this column contains the first 100 bytes. For functions specified in infix notation, FUNCTION_TEXT contains only the function name. For example, for a function named /, which overloads the SQL divide operator, if the function reference is A/B, FUNCTION_TEXT contains only /. |
FUNC_VERSION | VARCHAR(122) NOT NULL WITH DEFAULT | For a version of a non-inline SQL scalar function, this column contains the version identifier. For all other cases, this column contains a zero length string. A version of a non-inline SQL scalar function is defined in the SYSIBM.SYSROUTINES table with ORIGIN='Q', FUNCTION_TYPE='S', INLINE='N', and VERSION column containing the version identifier. |
SECURE | CHAR(1) NOT NULL WITH DEFAULT | Whether the user-defined function is secure. |
SECTNOI | INTEGER NOT NULL WITH DEFAULT | The section number of the statement. The value is taken from the same column in SYSPACKSTMT or SYSSTMT tables and can be used to join tables to reconstruct the access path for the statement. This column is applicable only for static statements. The default value of -1 indicates EXPLAIN information that was captured in DB2® 9 or earlier. |
VERSION | VARCHAR(122) NOT NULL WITH DEFAULT | The version identifier for the package. Applies only to an embedded EXPLAIN statement executed from a package or to a statement that is explained when binding a package. If the value is not blank, the value is the same as the VERSION value for the package that was used to create this EXPLAIN table row. The value is blank for a statement in:
|
EXPANSION_REASON | CHAR(2) NOT NULL WITH DEFAULT |
This column applies only to statements that reference archive tables or temporal tables. For other statements, this column is blank.
Indicates the effect of the CURRENT TEMPORAL BUSINESS_TIME special register, the CURRENT TEMPORAL SYSTEM_TIME special register, and the SYSIBMADM.GET_ARCHIVE built-in global variable. These items are controlled by the BUSTIMESENSITIVE, SYSTIMESENSITIVE, and ARCHIVESENSITIVE bind options. Db2 implicitly adds certain syntax to the query if one of the following conditions are true:
This column can have one of the following values:
|
PER_STMT_ID | BIGINT NOT NULL | The persistent statement identifier for SQL statements in Db2 catalog tables. For example, this column corresponds to the following catalog table columns that identify SQL statements:
|
AP_PLANID | CHAR(16) FOR BIT DATA | Used to uniquely identify the BIND or PREPARE optimizations for a SQL statement. Contains an extended timestamp value. |