This section describes the dynamic and static SQL support provided by Natural.
The following topics are covered:
For a list of error messages that may be issued during static generation, see Static Generation Messages and Codes Issued under NDB in the Natural Messages and Codes documentation.
For information on Static SQL with Natural Security, see Integration with Natural Security.
The SQL support of Natural combines the flexibility of dynamic SQL support with the high performance of static SQL support.
In contrast to static SQL support, the Natural dynamic SQL support does not require any
special consideration with regard to the operation of the SQL interface. All SQL
statements required to execute an application request are generated automatically and can
be executed immediately with the Natural RUN command. Before executing a program, you
can look at the generated SQLCODE, using the LISTSQL command.
Access to Db2 through Natural has the same form whether dynamic or static SQL support is used. Thus, with static SQL support, the same SQL statements in a Natural program can be executed in either dynamic or static mode. An SQL statement can be coded within a Natural program and, for testing purposes, it can be executed using dynamic SQL. If the test is successful, the SQL statement remains unchanged and static SQL for this program can be generated.
Thus, during application development, the programmer works in dynamic mode and all SQL statements are executed dynamically, whereas static SQL is only created for applications that have been transferred to production status.
Natural automatically provides for the preparation and execution of each SQL statement and handles the opening and closing of cursors used for scanning a table.
The following topics are covered:
As each dynamic execution of an SQL statement requires a statically defined
DECLARE STATEMENT and DECLARE CURSOR statement, a special
I/O module named NDBIOMO is provided which contains a fixed number of these
statements and cursors. This number is specified during the generation of the
NDBIOMO module in the course of the Natural for Db2 installation
process.
If possible, an SQL statement is only prepared once and can then be executed several
times if required. For this purpose, Natural internally maintains a table of all SQL
statements that have been prepared and assigns each of these statements to a
DECLAREd STATEMENT in the module NDBIOMO. In addition,
this table maintains the cursors used by the SQL statements SELECT, FETCH, UPDATE
(positioned), and DELETE
(positioned).
Each SQL statement is uniquely identified by:
the name of the Natural program that contains this SQL statement,
the line number of the SQL statement in this program,
the name of the Natural library into which this program was stowed,
the time stamp when this program was stowed.
Once a statement has been prepared, it can be executed several times with different
variable values, using the dynamic SQL statement EXECUTE USING DESCRIPTOR
or OPEN CURSOR USING DESCRIPTOR.
When the full capacity of the statement table is reached, the entry for the next prepared statement overwrites the entry for a free statement whose latest execution is the least recent one.
When a new SELECT
statement is requested, a free entry in the statement table with the corresponding
cursor is assigned to it and all subsequent FETCH, UPDATE, and DELETE statements referring to this SELECT statement will use this
cursor. Upon completion of the sequential scanning of the table, the cursor is released
and free for another assignment. While the cursor is open, the entry in the statement
table is marked as used and cannot be reused by another statement.
If the number of nested FIND (SELECT) statements reaches the
number of entries available in the statement table, any further SQL statement is
rejected at execution time and a Natural error message is returned.
The size of the statement table depends on the size specified for the module NDBIOMO. Since the
statement table is contained in the Db2 buffer area, the setting of Natural profile
parameter DB2SIZE
(see also Natural Parameter Modifications for Natural for Db2 in
Installing Natural
for Db2 on z/OS in the Installation
documentation) may not be sufficient and may need to be increased.
The embedded SQL uses cursor logic to handle SELECT statements. The preparation and execution of a
SELECT statement is done as follows:
The typical SELECT statement is prepared by a program flow which
contains the following embedded SQL statements (note that
X and
SQLOBJ are SQL variables, not program
labels):
DECLARE SQLOBJ STATEMENT DECLARE X CURSOR FOR SQLOBJ INCLUDE SQLDA (copy SQL control block)
Then, the following statement is moved into SQLSOURCE:
SELECT PERSONNEL_ID, NAME, AGE
FROM EMPLOYEES
WHERE NAME IN (?, ?)
AND AGE BETWEEN ? AND ?
Note:
The question marks (?) above are parameter markers which indicate where values
are to be inserted at execution time.
PREPARE SQLOBJ FROM SQLSOURCE
Then, the SELECT statement is executed as follows:
OPEN X USING DESCRIPTOR SQLDA FETCH X USING DESCRIPTOR SQLDA
The descriptor SQLDA is used to indicate a variable list of program
areas. When the OPEN statement is executed, it contains the address,
length, and type of each value which replaces a parameter marker in the
WHERE clause of the SELECT statement. When the FETCH statement is executed, it
contains the address, length, and type of all program areas which receive fields
read from the table.
When the FETCH statement is executed for the first time, it sets the
Natural system variable *NUMBER to a non-zero value if at least
one record is found that meets the search criteria. Then, all records satisfying the
search criteria are read by repeated execution of the FETCH
statement.
To help improve performance, especially when using distributed databases, the
Db2-specific FOR FETCH ONLY clause can be used. This clause is
generated and executed if rows are to be retrieved only; that is, if no updating is
to take place.
Once all records have been read, the cursor is released by executing the following statement:
CLOSE X
This section describes how to prepare Natural programs for static execution.
The following topics are covered:
For an explanation of the symbols used in this section to describe the syntax of Natural statements, see Syntax Symbols in the Statements documentation.
Static SQL is generated in Natural batch mode for one or more Natural applications which can consist of one or more Natural object programs. The number of programs that can be modified for static execution in one run of the generation procedure is limited to 999.
During the generation procedure, the database access statements contained in the specified Natural objects are extracted, written to work files, and transformed into a temporary Assembler program. If no Natural program is found that contains SQL access or if any error occurs during static SQL generation, batch Natural terminates and condition code 40 is returned, which means that all further JCL steps must no longer be executed.
The Natural modules NDBCHNK and NDBSTAT must reside in a
steplib of the generation step. Both are loaded dynamically during the execution of the
generation step.
The temporary Assembler program is written to a temporary file (the Natural work file
CMWKF06) and precompiled. The size of the workfile is proportional to the
maximum number of programs, the number of SQL statements and the number of variables
used in the SQL statements. During the precompilation step, a database request module
(DBRM) is created, and after the precompilation step, the precompiler output is
extracted from the Assembler program and written to the corresponding Natural objects,
which means that the Natural objects are modified (prepared) for static execution. The
temporary Assembler program is no longer used and deleted.
A static database request module is created by using either the sample job provided on the installation medium or an appropriate job created with the Create DBRM function.
The following topics are covered:
To generate static SQL for Natural programs
Logon to the Natural system library SYSDB2.
Since a new SYSDB2 library has been created when installing
Natural for Db2, ensure that it contains all Predict interface programs
necessary to run the static SQL generation. These programs are loaded into
SYSDB2 at Predict installation time (see the relevant
Predict product documentation).
Specify the CMD CREATE command and the Natural input
necessary for the static SQL generation process; the CMD
CREATE command has the following syntax:
CMD CREATE
DBRM
static-name
USING
using-clause |
{application-name,object-name,excluded-object} |
:
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:
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The generation procedure reads but does not modify the specified Natural objects. If one of the specified programs was not found or had no SQL access, return code 4 is returned at the end of the generation step.
Static-name either specifies the name of the DBRM to be created by the static generation for NDB or the name of the SQLJ profile to be created by the static generation of NDZ.
If the PREDICT
DOCUMENTATION option is to be used, a corresponding Predict
static SQL entry must be available and the
static-name must correspond to the name of
this entry. In addition, the static-name must
correspond to the name of the DBRM to be created during precompilation. The
static-name can be up to 8 characters long
and must conform to Assembler naming conventions.
The using-clause specifies the Natural
objects to be contained in the DBRM. These objects can either be specified explicitly
as INPUT DATA in the JCL or obtained as PREDICT
DOCUMENTATION from Predict.
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WITH XREF
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FS
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[LIB
lib-name
] |
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DCTODP
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If the parameters to be specified do not fit in one line, specify the command
identifier (CMD) and the various parameters in separate lines and use
both the input delimiter (as specified with the Natural profile/session parameter
ID - default is a
comma (,) - and the continuation character indicator - as specified with the Natural
profile/session parameter CF; default is a percent (%) - as shown in the
following example:
Example:
CMD CREATE,DBRM,static,USING,PREDICT,DOCUMENTATION,WITH,XREF,NO,% LIB,library
Alternatively, you can also use abbreviations as shown in the following example:
Example:
CMD CRE DBRM static US IN DA W XR Y FS OFF LIB library
The sequence of the parameters USING,
WITH, FS, and
LIB is optional.
As input data, the applications and names of the Natural objects to be included in
the DBRM must be specified in the subsequent lines of the job stream (
application-name,object-name). A subset of
these objects can also be excluded again
(excluded-objects). Objects in libraries
whose names begin with SYS can be used for static generation, too.
The applications and names of Natural objects must be separated by the input
delimiter - as specified with the Natural profile parameter ID; default is a comma (,).
If you wish to specify all objects whose names begin with a specific string of
characters, use an object-name or
excluded-objects name that ends with
asterisk notation (*). To specify all objects in an application, use asterisk notation
only.
Example:
LIB1,ABC* LIB2,A*,AB* LIB2,* : .
The specification of applications/objects must be terminated by a line that contains a period (.) only.
Since Predict supports static SQL for Db2, you can also have Predict supply the input
data for creating static SQL by using already existing PREDICT
DOCUMENTATION.
Since Predict Active References supports static SQL for Db2, the generated static DBRM can be documented in Predict, and the documentation can be used and updated with Natural.
WITH XREF is the option which enables you to store cross-reference data
for a static SQL entry in Predict each time a static DBRM is created
(YES). You can instead specify that no cross-reference data are stored
(NO) or that a check is made to determine whether a Predict static SQL
entry for this static DBRM already exists (FORCE). If so, cross-reference
data are stored; if not, the creation of the static DBRM is not allowed. For more
detailed information on Predict Active References, refer to the relevant Predict
documentation.
When WITH XREF (YES/FORCE) is specified, XREF data are
written for both the Predict static SQL entry (if defined in Predict) and each
generated static Natural program. However, static generation with WITH XREF
(YES/FORCE) is possible only if the corresponding Natural programs have been
cataloged with XREF ON.
WITH XREF FORCE only applies to the USING INPUT DATA
option.
Note:
If you do not use Predict, the XREF option must be omitted or set to
NO and the module NATXRF2 need not be linked to the
Natural nucleus.
If the FS (file server) option is set to ON, a second
SELECT is generated for the Natural file
server for Db2. ON is the default setting.
If the FS option is set to OFF, no second
SELECT is generated, which results in less SQL statements being
generated in your static DBRM and thus in a smaller DBRM.
With the LIB (library) option, a Predict library other than the default
library (*SYSSTA*) can be specified to contain the Predict static SQL
entry and XREF data. The name of the library can be up to eight
characters long.
The DCTODP option is only relevant if you are doing a static generation
for programs which have been catalogued with Natural parameter DC=’,’.
By the DCTODP parameter it can be determined whether the static
generation will change decimal literals in SQL statements by replacing the decimal
character comma ‘,’ by the decimal character period ‘.’ in the generated static SQL
assembler program. This will be necessary since the Db2 precompiler does not support
decimal point comma in decimal literals.
When DCTODP OFF is specified no conversion of decimal point comma to
decimal point period will take place. DCTODP OFF is the default
value.
When DCTODP ON is specified static generation will convert decimal point
comma to decimal point period.
If DCTODP ON is used, you should be sure your programs are coded
unambiguously when using the comma as separator in function calls and various SQL
clauses like IN or ORDER BY so that the comma as separator
in element lists can’t be misinterpreted as decimal point of a decimal literal
For instance, if you code a SQL IN clause while using DC=’,’ like
Column-name IN (10,20,30,40).
Static generation with DCTODP ON change the IN clause to
Column-name IN (10,20 , 30,40).
IN list contains two values 10.20 and 30.40.
The same IN clause in static generation with DCTODP OFF
(default value) will be changed to
Column-name IN (10,20 , 30,40).
IN list contains four values 10 , 20 , 30 and 40.
If you had coded
Column-name IN (10 , 20 , 30 , 40).
Static generation will always generate the IN clause with
DCTODP either ON or OFF to
Column-name IN (10 , 20 , 30 , 40).
In this step, the precompiler is invoked to precompile the generated temporary Assembler program. The precompiler output consists of the DBRM and a precompiled temporary Assembler program which contains all the database access statements transformed from SQL into Assembler statements.
Later, the DBRM serves as input for the BIND step and the Assembler
program as input for the modification step.
The modification procedure modifies the Natural objects involved by writing precompiler
information into the object and by marking the object header with the
static-name as specified with the
CMD CREATE command.
In addition, any existing copies of these objects in the Natural global buffer pool (if
available) are deleted and XREF data are written to Predict (if specified
during the generation procedure).
To perform the modification procedure
Logon to the Natural system library SYSDB2.
Specify the CMD MODIFY command which has the following syntax:
CMD MODIFY
[XREF]
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The input for the modify step is the precompiler output which must reside on a data set
defined as the Natural work file CMWKF01.
The output consists of precompiler information which is written to the corresponding Natural objects. In addition, a message is returned telling you whether it was the first time an object was modified for static execution (modified) or whether it had been modified before (re-modified).
If you specify the XREF option of the CMD
MODIFY command, an output listing is created on the work file
CMWKF02, which contains the DBRM name and the Assembler statement number
of each statically generated SQL statement together with the corresponding Natural
source code line number, program name, library name, database ID and file number.
-------------------------------------------------------------------------....
DBRMNAME STMTNO LINE NATPROG NATLIB DB FNR COMMENT ....
-------------------------------------------------------------------------....
TESTDBRM 000627 0390 TESTPROG SAG 010 042 INSERT ....
000641 0430 INSERT ....
000652 0510 SELECT ....
000674 0570 SELECT ....
000698 0570 SELECT 2ND ....
000728 0650 UPD/DEL ....
000738 0650 UPD/DEL 2ND ....
000751 0700 SELECT ....
000775 0700 SELECT 2ND .... |
| Column | Explanation |
|---|---|
DBRMNAME |
Name of the DBRM which contains the static SQL statement. |
STMTNO |
Assembler statement number of the static SQL statement. |
LINE |
Corresponding Natural source code line number. |
NATPROG |
Name of the Natural program that contains the static SQL statement. |
NATLIB |
Name of the Natural library that contains the Natural program. |
DB / FNR |
Natural database ID and file number. |
COMMENT |
Type of SQL statement, where 2ND indicates that the
corresponding statement is used for a reselection; see also the Concept of the File
Server.
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The modification procedure modifies the Natural objects involved by writing the SQLJ
profile sequence number into the object and by marking the object header with the
static-name of the SQLJ profile as
specified with the CMD CREATE command.
In addition, any existing copies of these objects in the Natural global buffer pool (if
available) are deleted and XREF data is written to Predict (if specified
during the generation procedure).
To perform the modification procedure
Logon to the Natural system library SYSDB2.
Specify the CMD MODIFYZ command which has the following syntax:
CMD MODIFYZ
[XREF]
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The input for the modifyz step is the generated SQL Assembler program by CMD
CREATE DBRM command output which resides on a data set defined as the Natural
work file CMWKF01.
The output consists of SQLJ information which is written to the corresponding Natural objects. In addition, a message is returned telling you whether it was the first time an object was modified for static execution (modified) or whether it had been modified before (remodified).
If you specify the XREF option of the CMD
MODIFYZ command, an output listing is created on the work file
CMWKF02, which contains the DBRM name and the Assembler statement number
of each statically generated SQL statement together with the corresponding Natural
source code line number, program name, library name, database ID, and file number.
-------------------------------------------------------------------------....
SQLJPROF SQLJNO LINE NATPROG NATLIB DB FNR COMMENT ....
-------------------------------------------------------------------------....
TESTDBRM 000000 0390 TESTPROG SAG 010 042 INSERT ....
000001 0430 INSERT ....
000002 0510 SELECT ....
000003 0570 SELECT ....
000004 0570 SELECT 2ND ....
000005 0650 UPD/DEL ....
000006 0650 UPD/DEL 2ND ....
000007 0700 SELECT ....
000008 0700 SELECT 2ND .... |
| Column | Explanation |
|---|---|
SQLJPROF |
Name of the SQLJ profile which contains the static SQL statement. |
SQLJNO |
SQLJ Assembler statement number of the static SQL statement. |
LINE |
Corresponding Natural source code line number. |
NATPROG |
Name of the Natural program that contains the static SQL statement. |
NATLIB |
Name of the Natural library that contains the Natural program. |
DB / FNR |
Natural database ID and file number. |
COMMENT |
Type of SQL statement, where 2ND indicates that the
corresponding statement is used for a reselection; see also the Concept of the File
Server.
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We recommend that you execute the Db2 BIND command after the
CMD MODIFY
command.
The Db2 BIND command binds the DBRM into a Db2 package. You can bind one
or more Db2 packages into a Db2 application plan. In addition to the packages of static
DBRMs created with the CMD
CREATE command, this application plan can also contain the package
of the DBRM of the NDBIOMO module Natural provides for dynamic SQL execution.
A DBRM can be bound into any number of packages and the packages can be bound into any number of application plans where required. A plan is physically independent of the environment where the program is to be run. However, you can group your packages logically into plans which are to be used for either batch or online processing, where the same package can be part of both a batch plan and an online plan.
Unless you are using plan switching, only one plan can be executed per Natural session.
Thus, you must ensure that the plan name specified in the BIND step is the
same as the one used to execute Natural.
The DB2 MF parameter setting of the Natural session that performs the static
generation, determines whether the DECLARE CURSOR statements of the
generated static program contain the WITH ROWSET POSITIONING clause.
The WITH ROWSET POSITIONING clause enables the static program to use
multi-fetching.
| Code | Explanation |
|---|---|
MF>0 |
WITH ROWSET POSITIONING clause is added to the DECLARE
CURSOR statements. Multi-fetching will be used with the value of the
MF parameter at execution time.
|
MF=0 |
No WITH ROWSET POSITIONING clause is added to the
DECLARE CURSOR statements. Multi-fetching is not possible,
regardless how the MF parameter is set at execution time. The
generated static program can only operate with single-fetching.
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To be able to execute Natural in static mode, all users of Natural must have the Db2
EXECUTE PLAN/PACKAGE privilege for the plan created in the
BIND step.
To execute static SQL, start Natural and execute the corresponding Natural program. Internally, the Natural runtime interface evaluates the precompiler data written to the Natural object and then performs the static accesses.
To the user there is no difference between dynamic and static execution.
It is possible to operate Natural in a mixed static and dynamic mode where for some programs static SQL is generated and for some not.
The mode in which a program is run is determined by the Natural object program itself. If a static DBRM is referenced in the executing program, all statements in this program are executed in static mode.
Note:
Natural programs which return a runtime error do not automatically execute in dynamic
mode. Instead, either the error must be corrected or, as a temporary solution, the Natural
program must be recataloged to be able to execute in dynamic mode.
Within the same Natural session, static and dynamic programs can be mixed without any further specifications. The decision which mode to use is made by each individual Natural program.
For a list of error messages that may be issued during static generation, refer to Static Generation Messages and Codes Issued under NDB in the Natural Messages and Codes documentation.
This section describes how to switch application plans within the same Natural session in different TP-monitor environments or in batch mode.
The following topics are covered:
When using application plan switching, you can switch to a different application plan within the same Natural session.
If a second application plan is to be used, this can be specified by executing the
Natural program NATPLAN. NATPLAN is contained in the Natural
system library SYSDB2 and can be invoked either from within a Natural
program or dynamically by entering the command NATPLAN at the
NEXT prompt. The only input value required for NATPLAN is an
eight-character plan name. If no plan name is specified, you are prompted by the system
to do so.
Before executing NATPLAN, ensure that any open Db2 recovery units are
closed.
Since the NATPLAN program is also provided in source form, user-written
plan switching programs can be created using similar logic.
The actual switch from one plan to another differs in the various environments supported. The feature is available under Com-plete, CICS, and IMS TM MPP. When using the Call Attachment Facility (CAF) or Resource Recovery Services Attachment Facility (RRSAF), it is also available in TSO and batch environments.
In some of these environments, a transaction ID or code must be specified instead of a plan name.
Under CICS, you have the option of using either plan switching by transaction ID
(default) or dynamic plan selection exit routines. Thus, by setting the field
#SWITCH-BY- TRANSACTION-ID in the NATPLAN program to either
TRUE or FALSE, either the subroutine CMTRNSET
or the desired plan name is written to temporary storage queue.
For more information on activating plan switching under CICS, see Installation Steps Specific to CICS in the Installing Natural for Db2 on z/OS documentation.
Below is information on:
If #SWITCH-BY-TRANSACTION-ID is set to FALSE, the desired
plan name is written to a temporary storage queue for a CICS/Db2 exit routine
specified as PLANExit attribute of a DB2ENTRY, or of the DB2CONN definition, the
NATPLAN program must be invoked before the first Db2 access. Natural
for Db2 provides NDBUEXT as CICS Db2 plan selection exit program. For
additional information on CICS/Db2 exit routines, refer to the relevant IBM
literature.
The name of the temporary storage queue is
PLANsssstttt, where
ssss is the remote or local CICS system
identifier and tttt the CICS terminal
identifier.
When running in a CICSplex environment, the CICS temporary storage queue
PLANsssstttt containing the plan name must
be defined with TYPE=SHARED or TYPE=REMOTE in a CICS
TST.
For each new Db2 unit of recovery, the appropriate plan selection exit routine is automatically invoked. This exit routine reads the temporary storage record and uses the contained plan name for plan selection.
When no temporary storage record exists for the Natural session, a default plan name contained in the plan exit can be used. If no plan name is specified by the exit, the name of the plan used is the same as the name of the static program (DBRM) issuing the SQL call. If no such plan name exists, an SQL error results.
In Com-plete environments, plan switching is accomplished by using the Call Attachment Facility (CAF), which releases the thread in use and attaches another one that has a different plan name.
Once the Db2 connection has been established, the same plan name continues to be used
until the plan is explicitly changed with IBM's call attachment language interface
(DSNALI). For additional information on the CAF interface, refer to the
relevant IBM literature.
Under Com-plete, the NATPLAN program first issues an END TRANSACTION statement and then invokes an Assembler
routine by using DB2SERV.
The assembler routine performs the actual switching. It issues a
CLOSE request to DSNALI to terminate the Db2
connection (if one exists). It then issues an OPEN request to
re-establish the Db2 connection and to allocate the resources needed to execute the
specified plan.
If NATPLAN has not been executed before the first SQL call, the default
plan used is the one defined in the Com-plete startup parameters. Once a plan has been
changed using NDBPLAN, it remains scheduled until another plan is scheduled
by NDBPLAN or until the end of the Natural session.
In an IMS MPP environment, the switch is accomplished by using direct or deferred message switching. As a different application plan is associated with each IMS application program, message switching from one transaction code to another automatically switches the application plan being used.
Since Natural applications can perform direct or deferred message switches by calling
the appropriate supplied routines, use of the NATPLAN program for plan
switching is optional.
NATPLAN calls the Assembler routine CMDEFSW, which sets the
new transaction code to be used with the next following terminal I/O.
In the TSO and batch environments, plan switching is accomplished by using the Call Attachment Facility (CAF) or the Resource Recovery Services Attachment Facility (RRSAF). Either facility releases the thread in use and attaches another one that has a different plan name.
Below is information on:
Initial connection and plan setting can be done using the subparameters DB2PLAN and
DB2SSID of the NTDB2 macro or of the DB2 profile parameter
without using the NATPLAN program. However, the initial settings could be
overwritten by using the NATPLAN program.
When using the Call Attachment Facility (CAF), plan selection is either implicit or explicit. If no Db2 connection has been made before the first SQL call, a plan name is selected by Db2. If so, the plan name used is the same as the name of the program (DBRM) issuing the SQL call.
Once the Db2 connection has been established, the plan name is retained until
explicitly changed by IBM's call attachment language interface (DSNALI).
For additional information on the CAF interface, refer to the relevant IBM
literature.
Under TSO and in batch mode, the NATPLAN program first issues an
END TRANSACTION statement
and then invokes an Assembler routine by using DB2SERV.
Note:
Modify the NATPLAN program by setting the #SSM field to
the current Db2 subsystem name; the default name is Db2.
The assembler routine performs the actual switching. It issues a
CLOSE request to DSNALI to terminate a
possible Db2 connection. It then issues an OPEN request to
re-establish the Db2 connection and to allocate the resources needed to execute the
specified plan.
If NATPLAN has not been executed before the first SQL call, plan
selection is done by DSNALI. If so, the plan name used is the same as the
name of the program issuing the SQL call. The subsystem ID used is the one specified
during the Db2 installation. If no such plan name or subsystem ID exists, a Natural
error message is returned.
If a static DBRM issues the SQL call, a plan name must exist with the same name as the one of the static DBRM.
If dynamic SQL is used, a Db2 plan must exist which contains a package with the DBRM
of the NDBIOMO module. If the name of the Db2 plan has neither been
defined in the NATPLAN program nor with the
DB2PLAN keyword subparameter, the Db2 Call Attachment
Facility (CAF) uses the name of the NDBIOMO DBRM as the default plan
name.
Note:
To avoid any confusion concerning the chosen plan name and/or subsystem ID,
always call NATPLAN before the first SQL call.
Initial connection and plan setting can be done using the keyword subparameters
DB2COLL, DB2GROV,
DB2PLAN, DB2SSID and
DB2XID
of the NTDB2 macro or of the DB2 profile parameter
without using the NATPLAN program. However, the initial settings can be
overwritten by using the NATPLAN program.
When using the Resource Recovery Services Attachment Facility (RRSAF), plan selection is explicit.
RRSAF is used if IBM's DSNRLI interface module is linked to Natural.
Once the Db2 connection has been established, the plan name is retained until
explicitly changed with RRSAF. For additional information on RRSAF, refer to the
relevant IBM literature.
The NATPLAN program performs the actual switching. It issues a
TERMINATE IDENTIFY request to DSNRLI to
terminate a possible Db2 connection. NATPLAN then issues an
IDENTIFY request to re-establish the Db2 connection. This
request is followed by SIGNON and CREATE
THREAD requests.
In an RRSAF environment, up to four of the following parameters can be specified in
NATPLAN where #PLAN is mandatory:
| Parameter | Default Value | Format | Explanation |
|---|---|---|---|
#PLAN |
None | A8 | Name of the plan used for SQL processing in the thread created
(CREATE THREAD).
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#SSM |
DB2 |
A4 | Subsystem ID of the Db2 server connected (IDENTIFY).
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#COLLID |
COLLID |
A18 |
Only used if the first character of #PLAN is a question mark (?). Collection ID used for SQL processing in the thread created
( |
#XID |
1 |
I4 |
Indicates that a global transaction ID is used. If set to0
(SIGNON), no global transaction ID is
used.
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Example of Plan Selection with RRSAF under TSO
The example below demonstrates plan selection under TSO by using RRSAF.
NATPLAN
<Enter>
Please enter new plan name NDBPLAN4
,SUB SYSTEM ID DB27
,COLLECTION ID
,global XID (0/1) __________1
<Enter>
The example below demonstrates plan selection in batch mode by using RRSAF:
NATPLAN NDBPLAN4,DB27, ,1