The following is a list of DB2 registry variables and environment variables that you may need to know about to get up and running. Each has a brief description; some may not apply to your environment.
You can view a list of all supported registry variables by using:
db2set -lr
You can change the value for a variable for the current session by using:
db2set registry_variable_name=new_value
The values for the changed registry variables must be set before the
DB2START command is issued. See "Using the db2set Command" for more information on changing and using registry variables.
| Parameter | Operating System | Values | Description | ||
|---|---|---|---|---|---|
| General | |||||
| DB2ACCOUNT | All | Default=null | The accounting string that is sent to the remote host. Refer to the DB2 Connect User's Guide for details. | ||
| DB2BIDI | All | Default=NO
Values: YES or NO | Enables bidirectional CCSID processing. See "Bidirectional CCSID Support" for additional information. Refer to the DB2 Connect Release Notes for details on configuration. | ||
| DB2CODEPAGE | All | Default: derived from the language ID, as specified by the operating system. | Specifies the code page of the data presented to DB2 for database client application. The user should not set db2codepage unless explicitly stated in DB2 documents, or asked to do so by DB2 service. Setting db2codepage to a value not supported by the operating system can produce unexpected results. Normally, you do not need to set db2codepage because DB2 automatically derives the code page information from the operating system. | ||
| DB2COUNTRY | All | Default: derived from the language ID, as specified by the operating system. | Specifies the country code of the client application, which influences date and time formats. | ||
| DB2DBDFT | All | Default=null | Specifies the database alias name of the database that will be implicitly connected to when applications are started and no implicit connect has been done. This keyword is ignored if it is set. | ||
| DB2DBMSADDR | Windows 32-bit operating systems | Default=0x20000000 for Windows NT, 0x90000000 for Windows 95
Value: 0x20000000 to 0xB0000000 in increments of 0x10000 | Specifies the default database manager shared memory address in hexadecimal format. If a shared memory address collision occurs, this value can be modified to force the database manager instance to allocate its shared memory at a different address. | ||
| DB2DISCOVERYTIME | OS/2 and Windows 32-bit operating systems | Default=40 seconds,
Minimum=20 seconds | Specifies the amount of time that SEARCH discovery will search for DB2 systems. | ||
| DB2INCLUDE | All | Default=null | Specifies a path to be used during the processing of the SQL INCLUDE text-file statement during DB2 PREP processing. It provides a list of directories where the INCLUDE file might be found. Refer to the Embedded SQL Programming Guide for descriptions of how db2include is used in the different precompiled languages. | ||
| DB2INSTDEF | OS/2 and Windows 32-bit operating systems | Default=DB2 | Sets the value to be used if DB2INSTANCE is not defined. | ||
| DB2NBDISCOVERRCVBUFS | All | Default=16 buffers,
Minimum=16 buffers | This variable is used for NetBIOS search discovery. The variable specifies the number of concurrent discovery responses that can be received by a client. If the client receives more concurrent responses than are specified by this variable, then the excess responses are discarded by the NetBIOS layer. The default is sixteen (16) NetBIOS receive buffers. If a number less than the default value is chosen, then the default is used. | ||
| DB2SLOGON | Windows 3.x | Default=null,
Values: YES or NO | Enables a secure logon in DB2 for Windows 3.x. If db2slogon=YES DB2 does not write user IDs and passwords to a file, but instead uses a segment of memory to maintain them. When db2slogon is enabled, the user must logon each time Windows 3.x is started. | ||
| DB2TIMEOUT | Windows 3.x and Macintosh | Default=(disabled) | Used to control the timeout period for Windows 3.x and Macintosh clients during long SQL queries. After the timeout period has expired a dialog box pops up asking if the query should be interrupted or allowed to continue. The minimum value for this variable is 30 seconds. If db2timeout is set to a value between 1 and 30, the default minimum value will be used. If db2timeout is set to a value of 0, or a negative value, the timeout feature is disabled. This feature is disabled by default. | ||
| DB2TRACENAME | Windows 3.x and Macintosh | Default=DB2WIN.TRC (on Windows 3.x), DB2MAC.TRC (on Macintosh) | On Windows 3.x and Macintosh, specifies the name of the file where trace information is stored. The default for each system is saved in your current instance directory (for example, \sqllib\db2). We strongly recommend that you specify the full path name when naming the trace file. | ||
| DB2TRACEON | Windows 3.x and Macintosh | Default=NO
Values: YES or NO | On Windows 3.x and Macintosh, turns trace on to provide information to IBM in case of a problem. (It is not recommended that you turn trace on unless you encounter a problem you cannot resolve.) Refer to the Troubleshooting Guide for information on using the trace facility with DB2 Client Application Enabler. | ||
| DB2TRCFLUSH | Windows 3.x and Macintosh | Default=NO
Values: YES or NO | On Windows 3.x and Macintosh, db2trcflush can be used in conjunction with db2traceon=YES. Setting db2trcflush=YES will cause each trace record to be written immediately into the trace file. This will slow down your DB2 system considerably, so the default setting is db2trcflush=NO. This setting is useful in cases where an application hangs the system and requires the system to be rebooted. Setting this keyword guarantees that the trace file and trace entries are not lost by the reboot. | ||
| DB2TRCSYSERR | Windows 3.x and Macintosh | Default=1
Values: 1-32767 | Specifies the number of system errors to trace before the client turns off tracing. The default value traces one system error, after which, trace is turned off. | ||
| DB2YIELD | Windows 3.x | Default=NO
Values: YES or NO | Specifies the behavior of the Windows 3.x client while communicating with a remote server. When set to NO, the client will not yield the CPU to other Windows 3.x applications, and the Windows environment is halted while the client application is communicating with the remote server. You must wait for the communications operation to complete before you can resume any other tasks. When set to YES, your system functions as normal. It is recommended that you try to run your application with db2yield=YES. If your system crashes, you will need to set db2yield=NO. For application development, ensure your application is written to accept and handle Windows messages while waiting for a communications operation to complete. | ||
| System Environment | |||||
| DB2ENVLIST | UNIX | Default: null | Lists specific variable names for either stored procedures or user-defined functions. By default, the db2start command filters out all user environment variables except those prefixed with DB2 or db2. If specific registry variables must be passed to either stored procedures or user-defined functions, you can list the variable names in the db2envlist registry variable. Separate each variable name by one or more spaces. DB2 constructs its own PATH and LIBPATH, so if PATH or LIBPATH is specified in db2envlist, the actual value of the variable name is appended to the end of the DB2-constructed value. | ||
| DB2INSTANCE | All | Default=db2instdef on OS/2 and Windows 32-bit operating systems. | The environment variable used to specify the instance that is active by default. On UNIX, users must specify a value for DB2INSTANCE. | ||
| DB2INSTPROF | OS/2, Windows 3.x, and Windows 32-bit operating systems | Default: null | The environment variable used to specify the location of the instance directory on OS/2, Windows 3.x, and Windows 32-bit operating systems, if different than DB2PATH. | ||
| DB2LIBPATH | UNIX | Default: null | Specifies the value or LIBPATH in the db2libpath registry variable. The value of LIBPATH cannot be inherited between parent and child processes if the user ID has changed. Since the db2start executable is owned by root, DB2 cannot inherit the LIBPATH settings of end users. If you list the variable name, LIBPATH, in the db2envlist registry variable, you must also specify the value of LIBPATH in the db2libpath registry value. The db2start executable then reads the value of db2libpath and append this value to the end of the DB2-constructed LIBPATH. | ||
| DB2PATH | OS/2, Windows 3.x, and Windows 32-bit operating systems | Default: (varies by operating system) | The environment variable used to specify the directory where the product is installed on OS/2, Windows 3.x, and Windows 32-bit operating systems. | ||
| Communications | |||||
| DB2CHECKCLIENTINTERVAL | AIX, server only | Default=0
Values: A numeric value greater than zero. | Used to verify the status of APPC client connections. Permits early detection of client termination, rather than waiting until after the completion of the query. When set to zero, no check will be made. When set to a numerical value greater than zero, the value represents DB2 internal work units. For guidance, the following check frequency values are given: Low frequency use 300; medium frequency use 100; high frequency use 50. Checking more frequently for client status while executing a database request lengthens the time taken to complete the queries. If the DB2 workload is heavy (that is, it involves many internal requests), then setting DB2CHECKCLIENTINTERVAL to a low value has a greater impact on performance than in a situation where the workload is light and most of the time DB2 is waiting. | ||
| DB2COMM | All, server only | Default=null
Values: any combination of APPC,IPXSPX, NETBIOS,NPIPE, TCPIP | Specifies the communication managers that are started when the database manager is started. If this is not set, no DB2 communications managers are started at the server. | ||
| DB2_FORCE_NLS_CACHE | AIX, HP_UX, Solaris | Default=FALSE
Values: TRUE or FALSE | Used to eliminate the change of lock contention in multi-threaded applications. When this registry variable is "TRUE", the code page and country code information is saved the first time a thread accesses it. From that point, the cached information is used for any other thread that requests this information. This eliminates lock contention and results in a performance benefit in certain situations. This setting should not be used if the application changes locale settings between connections. It is likely not needed in such a situation anyway, since multi-threaded applications typically do not change their locale settings because it is not "thread-safe" to do so. | ||
| DB2NBADAPTERS | OS/2 and Windows NT, server only | Default=0
Range: 0-15, Multiple values should be separated by commas | Used to specify which local adapters to use for DB2 NetBIOS LAN communications. Each local adapter is specified using its logical adapter number. | ||
| DB2NBCHECKUPTIME | OS/2 and Windows NT, server only | Default=1 minute
Values: 1-720 | Specifies the time interval between each invocation of the NetBIOS
protocol checkup procedure. Checkup time is specified in
minutes.
Lower values will ensure that the NetBIOS protocol checkup runs more often, freeing up memory and other system resources left when unexpected agent/session termination occurs. | ||
| DB2NBINTRLISTENS | OS/2 and Windows NT, server only | Default=1
Values: 1-10 Multiple values should be separated by commas | Specifies the number of NetBIOS listen send commands (NCBs) that will be
asynchronously issued in readiness for remote client interrupts. This
flexibility is provided for "interrupt active" environments to ensure that
interrupt calls from remote clients will be able to establish connections when
servers are busy servicing other remote interrupts.
Setting db2nbintrlistens to a lower value will conserve NetBIOS sessions and NCBs at the server. However, in an environment where client interrupts are common, you may need to set db2nbintrlistens to a higher value in order to be responsive to interrupting clients.
| ||
| DB2NBRECVBUFFSIZE | OS/2 and Windows NT, server only | Default=4096 bytes
Range: 4096-65536 | Specifies the size of the DB2 NetBIOS protocol receive buffers. These buffers are assigned to the NetBIOS receive NCBs. Lower values conserve server memory, while higher values may be required when client data transfers are larger. | ||
| DB2NBBRECVNCBS | OS/2 and Windows NT, server only | Default=10
Range: 1-99 | Specifies the number of NetBIOS "receive_any" commands (NCBs) that the
server will issue and maintain during operation. This value may be
adjusted depending on the number of remote clients to which your server is
connected. Lower values will conserve server resources.
| ||
| DB2NBRESOURCES | OS/2 and Windows NT server only | Default=null | Specifies the number of NetBIOS resources to allocate for DB2 use in a multi-context environment. This variable is restricted to multi-context client operation. | ||
| DB2NBSENDNCBS | OS/2 and Windows NT, server only | Default=6
Range: 1-720 | Specifies the number of send NetBIOS commands (NCBs) that the server will reserve for use. This value may be adjusted depending on the number of remote clients your server is connected to. Setting db2nbsendncbs to a lower value will conserve server resources. However, you may need to set it to a higher value to prevent the server from waiting to send to a remote client when all other send commands are in use. | ||
| DB2NBSESSIONS | OS/2 and Windows NT, server only | Default=null
Range: 5-254 | Specifies the number of sessions that DB2 should request to be reserved
for DB2 use. The value of db2nbsessions can be set to request
a specific session for each adapter specified using
db2nbadapters.
| ||
| DB2NBXTRANCBS | OS/2 and Windows NT, server only | Default=5 per adapter
Range: 5-254 | Specifies the number of "extra" NetBIOS commands (NCBs) the server will need to reserve when the db2start command is issued. The value of db2nbxtrancbs can be set to request a specific session for each adapter specified using db2nbadapters. | ||
| DB2NETREQ | Windows 3.x | Default=3
Range: 0-25 | Specifies the number of NetBIOS requests that can be run concurrently on Windows 3.x clients. The higher you set this value, the more memory below the 1MB level will be used. When the concurrent number of requests to use NetBIOS services reaches the number you have set, subsequent incoming requests for NetBIOS services are held in a queue and become active as the current requests complete. If you enter 0 (zero) for db2netreq, the Windows database client issues NetBIOS calls in synchronous mode using the NetBIOS wait option. In this mode, the database client allows only the current NetBIOS request to be active and does not process another one until the current request has completed. This can affect other application programs. The 0 value is provided for backwards compatibility only. It is strongly recommended that 0 not be used. | ||
| DB2RETRY | OS/2 and Windows NT | Default=0
Range: 0-20 000 | The number of times DB2 attempts to restart the APPC listener. If the SNA subsystem at the server/gateway is down, this profile variable, in conjunction with db2retrytime, can be used to automatically restart the APPC listener without disrupting client communications using other protocols. In such a scenario, it is no longer necessary to stop and restart DB2 to reinstate the APPC client communications. | ||
| DB2RETRYTIME | OS/2 and Windows NT | Default=1 minute
Range: 0-7 200 minutes | In increments of one minute, the number of minutes that DB2 allows between performing successive retries to start the APPC listener. If the SNA subsystem at the server/gateway is down, this profile variable, in conjunction with db2retry, can be used to automatically restart the APPC listener without disrupting client communications using other protocols. In such a scenario, it is no longer necessary to stop and restart DB2 to reinstate the APPC client communications. | ||
| DB2SERVICETPINSTANCE | OS/2 and Windows NT | Default=null | Used to support incoming APPC connections from DB2 workstation V.1
clients or from the DB2 MVS database. When the db2start
command is invoked, the instance specified will start the APPC listeners for
the following TP names:
| ||
| DB2SOSNDBUF | Windows 95 and Windows NT | Default=32767 | Specifies the value of TCP/IP send buffers on Windows 95 and Windows NT operating systems. | ||
| DB2SYSPLEX_SERVER | OS/2, Windows NT, and UNIX | Default=null | Specifies whether SYSPLEX exploitation when connected to DB2 for OS/390 is enabled. If this registry variable is not set (which is the default), or is set to a non-zero value, exploitation is enabled. If this registry variable is set to zero (0), exploitation is disabled. When set to zero, SYSPLEX exploitation is disabled for the gateway regardless of how the DCS database catalog entry has been specified. For more information see the Command Reference and the CATALOG DCS DATABASE command. | ||
| DB2_VI_ENABLE | Windows NT | Default=OFF
Values: ON or OFF | Specifies whether to use the Virtual Interface Architecture (VIA)
communication protocol or not. If this registry variable is "ON",
then FCM will use VI for inter-node communication. If this registry
variable is "OFF", then FCM will use TCP/IP for inter-node
communication.
| ||
| DB2_VI_VIPL | Windows NT | Default=vipl.dll | Specifies the name of the Virtual Interface Provider Library (VIPL) that will be used by DB2. In order to load the library successfully, the library name used in this registry variable must be in the %path% user environment variable. | ||
| DB2_VI_DEVICE | Windows NT | Default=null | Specifies the symbolic name of the device or Virtual Interface Provider Instance associated with the Network Interface Card (NIC). Independent hardware vendors (IHVs) each produce their own NIC. Only one (1) NIC is allowed per Windows NT machine; Multiple logical nodes on the same physical machine will share the same NIC. | ||
| DCE Directories | |||||
| DB2DIRPATHNAME | OS/2, UNIX, and Windows 32-bit operating systems | Default=null | Specifies a temporary override of the DIR_PATH_NAME parameter value
in the database manager configuration file. If a directory server is
used and the target of a CONNECT statement or ATTACH command is not explicitly
cataloged, then the target is concatenated with DB2DIRPATHNAME (if specified)
to form the fully qualified DCE name.
| ||
| DB2CLIENTCOMM | OS/2, UNIX, and Windows 32-bit operating systems | Default=null | Specifies a temporary override of the DFT_CLIENT_COMM parameter value in the database manager configuration file. If both DFT_CLIENT_COMM and db2clientcomm are not specified, then the first protocol found in the object is used. If either one or both of them are specified, then only the first matching protocol will be used. In either case, no retry is attempted if the first connect fails. | ||
| DB2CLIENTADPT | OS/2 and Windows 32-bit operating systems | Default=null
Range: 0-15 | Specifies the client adapter number for NETBIOS protocol on OS/2 operating systems. The db2clientadpt value overrides the DFT_CLIENT_ADPT parameter value in the database manager configuration file. | ||
| DB2ROUTE | OS/2, UNIX, and Windows 32-bit operating systems | Default=null | Specifies the name of the Routing Information Object the client uses when it connects to a database with a different database protocol. The db2route value overrides the ROUTE_OBJ_NAME parameter value in the database manager configuration file. | ||
| Command Line Processor | |||||
| DB2BQTIME | All | Default=1 second
Maximum value: 1 second | Specifies the amount of time the command line processor front end will sleep before checking if the back end process is active and establishing a connection to it. | ||
| DB2BQTRY | All | Default=60 retries
Minimum value: 0 retries | Specifies the number of times the command line processor front end process tries to determine whether the back end process is already active. It works in conjunction with db2bqtime. | ||
| DB2IQTIME | All | Default=5 seconds
Minimum value: 1 second | Specifies the amount of time the command line processor back end process waits on the input queue for the front end process to pass commands. | ||
| DB2OPTIONS | All | Default=null | Sets command line processor options. | ||
| DB2RQTIME | All | Default=5 seconds
Minimum value: 1 second | Specifies the amount of time the command line processor back end process waits for a request from the front end process. | ||
| MPP Configuration | |||||
| DB2ATLD_PORTS | DB2 UDB EEE on AIX, Solaris, and Windows NT | Default=6000:6063
Value: num1:num2 where both are between 1 and 65535, and num1<=num2 | Specifies the range of port numbers used for the AutoLoader utility's internal TCPIP communication. If not set, AutoLoader uses the internal default port range 6000:6063. When you have other applications using the AutoLoader default port range, this variable can be used to select an alternate port range. | ||
| DB2ATLD_PWFILE | DB2 UDB EEE on AIX, Solaris, and Windows NT | Default=null
Value: a file path expression | Specifies a path to a file that contains a password used during AutoLoader authentication. If not set, AutoLoader either extracts the password from its configuration file or prompts you interactively. Using this variable will address password security concerns and allows the separation of AutoLoader configuration information from authentication information. | ||
| DB2_FORCE_FCM_BP | AIX | Default=NO
Values: YES or NO | This registry variable is applicable to DB2 UDB EEE for AIX when using multiple logical partitions. When DB2START is issued, DB2 allocates the FCM buffers from the database global memory or, if there is not enough room there, from a separate shared memory segment which is used by all FCM daemons (for that instance) on the same physical machine. Which it chooses is largely dependent on the number of FCM buffers to be created (which, in turn, is determined by the FCM_NUM_BUFFERS database manager configuration parameter). If this registry variable is ON, the FCM buffers are always created in a separate memory segment. When the FCM buffers are created in a separate memory segment, the communication between FCM daemons of different logical partitions on the same physical node occurs through shared memory. Otherwise, FCM daemons on the same node communicate through UNIX Sockets. The advantage of communicating through shared memory in this way is that it is faster. The disadvantage is that there is one fewer shared memory segments available for other uses, most notably database buffer pools. This reduces the maximum size of database buffer pools. | ||
| DB2INSTOWNER | Windows NT | Default=null | Specifies the machine name of the instance owning machine. | ||
| DB2NODE | All | Default=null
Values: 1-999 | Specifies which node of the MPP server instance you want to connect or attach to. | ||
| DB2PORTRANGE | Windows NT | Values: nnnn:nnnn | This value is set to the TCP/IP port range used by FCM so that any additional partitions created on another machine will also have the same port range. | ||
| SQL Complier | |||||
| DB2_CORRELATED_PREDICATES | All | Default=OFF
Values: ON or OFF | When there are unique indexes on correlated columns in a join, and this registry variable is ON, the optimizer attempts to detect and compensate for correlation of join predicates. When this registry variable is ON, the optimizer uses the KEYCARD information of unique index statistics to detect cases of correlation, and dynamically adjusts the combined selectivities of the correlated predicates, thus obtaining a more accurate estimate of the join size and cost. | ||
| DB2_PRED_FACTORIZE | All | Default=NO
Value: YES or NO | Specifies whether the optimizer will search for opportunities to extract
additional predicates from disjuncts. In some circumstances, the
additional predicates can alter the estimated cardinality of the intermediate
and final result sets. With the following query:
SELECT n1.empno, n1.lastname
FROM employee n1, employee n2
WHERE ((n1.lastname='SMITH'
AND n2.lastname='JONES')
OR (n1.lastname='JONES'
AND n2.lastname='SMITH'))
the optimizer can generate the following additional predicates: SELECT n1.empno, n1.lastname
FROM employee n1, employee n2
WHERE n1.lastname IN ('SMITH',
'JONES')
AND n2.lastname IN ('SMITH',
'JONES')
AND ((n1.lastname='SMITH'
AND n2.lastname='JONES')
OR (n1.lastname='JONES'
AND n2.lastname='SMITH'))
| ||
| DB2_VECTOR | All | Default=OFF
Values: OFF or ON | When processing SQL statements using a GROUP BY with column functions where aggregation is performed inside a sort, this registry variable determines if a vectored approach is used to aggregate the row into groups. When this registry variable is ON, input values associated with rows are stored in a vector area and aggregation operations are performed on the contents of the vector area as a whole. When this registry variable is OFF, each new row is aggregated into its group immediately; a vector area and vector aggregation operations are not used. | ||
| Performance | |||||
| DB2_AVOID_PREFETCH | All | Default=OFF,
Values: ON or OFF | Specifies whether or not prefetch should be used during crash recovery. If db2_avoid_prefetch=ON, prefetch is not used. | ||
| DB2CHKPTR | All | Default=OFF,
Values: ON or OFF | Specifies whether or not pointer checking for input is required. | ||
| DB2_MMAP_READ | AIX | Default=ON ,
Values: ON or OFF | Used in conjunction with db2_mmap_write to allow DB2 to use mmap as an alternate method of I/O. In most environments, mmap should be used to avoid operating system locks when multiple processes are writing to different sections of the same file. However, perhaps you migrated from Parallel Edition V1.2 where the default was OFF allowing AIX chaching of DB2 data read from JFS filesystems into memory (outside the buffer pool). If you want the comparable performance with DB2 UDB, you can either increase the size of the buffer pool, or change db2_mmap_read and db2_mmap_write to OFF. | ||
| DB2_MMAP_WRITE | AIX | Default=ON
Values: ON or OFF | Used in conjunction with db2_mmap_read to allow DB2 to use mmap as an alternate method of I/O. In most environments, mmap should be used to avoid operating system locks when multiple processes are writing to different sections of the same file. However, perhaps you migrated from Parallel Edition V1.2 where the default was OFF allowing AIX caching of DB2 data read from JFS filesystems into memory (outside the buffer pool). If you want the comparable performance with DB2 UDB, you can either increase the size of the buffer pool, or change db2_mmap_read and db2_mmap_write to OFF. | ||
| DB2_NO_PKG_LOCK | All | Default=OFF
Values: ON or OFF | Allows the Global SQL Cache to operate without the use of package locks to protect cached package entries. (Package locks are internal system locks.) To improve performance (because acquiring and freeing locks takes time), you can now choose to work in a "no package lock" mode. In this mode, certain database operations are not allowed. These operations may include: operations that invalidate packages, operations that inoperate packages, and operations that directly change a package. | ||
| DB2NTMEMSIZE | Windows NT | Default=(varies by memory segment) | Windows NT requires that all shared memory segments be reserved at DLL
initialization time in order to guarantee matching addresses across
processes. DB2NTMEMSIZE has been introduced to permit the user
to override the DB2 defaults on Windows NT if necessary. In most
situations, the default values should be sufficient. The memory
segments, default sizes, and override options are: 1) Database
Kernel: default size is 16777216 (16 MB); override option is
DBMS:<number of bytes>. 2) Parallel FCM Buffers:
default size is 22020096 (21 MB); override option is FCM:<number of
bytes>. 3) Database Admin GUI: default size is 33554432 (32
MB); override option is DBAT:<number of bytes>. 4) Fenced
Stored Procedures: default size is 16777216 (16 MB); override option is
APLD:<number of bytes>. More than one segment may be
overridden by separating the override options with a semi-colon
(;). For example, to limit the database kernel to approximately
256K, and the FCM buffers to approximately 64 MB, use:
db2set DB2NTMEMSIZE= DBMS:256000;FCM:64000000 | ||
| DB2NTNOCACHE | Windows NT | Default=OFF
Value: ON or OFF | Specifies whether or not DB2 will open database files with a NOCACHE option. If db2ntnocache=ON, file system caching is eliminated. If db2ntnocache=OFF, the operating system caches DB2 files. This applies to all data except for files that contain LONG FIELDS or LOBS. Eliminating system caching allows more memory to be available to the database so that the bufferpool or sortheap can be increased. | ||
| DB2NTPRICLASS | Windows NT | Default=null
Value: R, H, (any other value) | Sets the priority class for the DB2 instance (program
DB2SYSCS.EXE). There are three priority classes:
This variable is used in conjunction with individual thread priorities (set using DB2PRIORITIES) to determine the absolute priority of DB2 threads relative to other threads in the system.
For more information, please refer to the SetPriorityClass() API in the Win32 documentation. | ||
| DB2NTWORKSET | Windows NT | Default=1,1 | Used to modify the minimum and maximum working set size available to
DB2. When you are not in a paging situation, a process's working
set can grow as large as needed. When paging occurs, the maximum
working set that a process can have is approximately 1 MB.
Specify db2ntworkset for DB2 using the syntax db2ntworkset=min,max, where min and max are expressed in megabytes. | ||
| DB2PRIORITIES | All | Values setting is platform dependent. | Controls the priorities of DB2 processes and threads. | ||
| DB2_RR_TO_RS | All | Default=NO
Values: YES or NO | Specifies whether or not next-key locking occurs on access to user tables. When set to YES, next-key locking will not be activated. | ||
| Miscellaneous | |||||
| DB2ADMINSERVER | OS/2, Windows 95, Windows NT, and UNIX | Default=null | Specifies which DB2 instance is set up as the DB2 Administration Server. | ||
| DB2CLIINIPATH | All | Default=null | Used to override the default path of the DB2 CLI/ODBC configuration file (db2cli.ini) and specify a different location on the client. The value specified must be a valid path on the client system. | ||
| DB2DATALINK | All except Windows 3.x | Default=NO
Values: NO or YES | Specifies that the DB2 database manager will have to contact a DB2 File Manager Server if a table containing the DATALINK datatype column is accessed. | ||
| DB2DEFPREP | All | Default=NO
Values: ALL, YES, or NO | Simulates the runtime behavior of the DEFERRED_PREPARE precompile option for applications that were precompiled prior to this option becoming available. For example, if a DB2 v2.1.1 or earlier application were run in a DB2 v2.1.2 or later environment, db2defprep could be used to indicate the desired 'deferred prepare' behavior. | ||
| DB2DMNBCKCTLR | Windows NT | Default=null
Values: ? or a domain name | If you know the name of the domain for which DB2 server is the backup
domain controller, set
db2dmnbckctlr=DOMAIN_NAME. The DOMAIN_NAME
must be in upper case. To have DB2 determine the domain for which the
local machine is a backup domain controller, set
db2dmnbckctlr=?. If the
db2dmnbckctlr profile variable is not set or is set to blank, DB2
performs authentication at the primary domain controller.
| ||
| DB2_FALLBACK | Windows NT | Default=OFF
Values: ON or OFF | This variable allows you to force all database connections off during the fallback processing. It is used in conjunction with the failover support in the Windows NT environment with Microsoft Cluster Server (MSCS). If DB2_FALLBACK is not set or is set to OFF, and a database connection exists during the fall back, the DB2 resource cannot be brought offline. This will mean the fallback processing will fail. | ||
| DB2_FORCE_TRUNCATION | All | Default=NO
Values: YES or NO | Used during restart recovery. If set to "NO", it will halt restart recovery if it is determined that a bad page is stopping the restart recovery too soon (that is, all active logs have not been read). This is usually caused by a bad page in one of the logs. The user can set this variable to "YES" to signal restart recovery that it should continue processing as if the end of logs was reached. After setting the variable to "YES", logs not read during restart recovery are overwritten when the database becomes active again. The default is "NO", which is not to proceed if a bad page is not found. Use this variable only under the direction from IBM Service personnel. | ||
| DB2_GRP_LOOKUP | Windows NT | Default=null | Specifies which Windows NT security mechanism will be used to enumerate the groups that a user belongs to. | ||
| DB2_LIKE_VARCHAR | All | Default=NO
Values: YES, NO, or a floating point constant | Specifies how the optimizer works with a predicate of the form
COLUMN LIKE '%XXXXXX%' where the xxxxxx is any string of characters. For all predicates, the optimizer has to estimate how many rows match the predicate. For LIKE predicates with leading and trailing % characters, the optimizer assumes that the COLUMN being matched has a structure of a series of elements concatenated together to form the entire column. The optimizer then estimates the length of each element based on the length of the string enclosed in the % characters. | ||
| DB2LOADREC | All | Default=null | Used to override the location of the load copy during roll forward. If the user has changed the physical location of the load copy, db2loadrec must be set before issuing the roll forward. | ||
| DB2_LOADSORT_STACKSZ | All | Default=262144 (256 KB)
Values: stack size in bytes | Redefines the size of the thread stack size used by the sorting routines. For example, the LOAD utility uses one thread per index. | ||
| DB2LOCK_TO_RB | All | Default=null
Values: Statement | Specifies whether lock timeouts cause the entire transaction to be rolled-back, or only the current statement. If db2lock_to_rb is set to STATEMENT before the db2start command is issued, locked timeouts cause only the current statement is rolled back. Any other setting results in transaction rollback. | ||
| DB2NOEXITLIST | All | Default=OFF
Values: ON or OFF | If defined, this variable indicates to DB2 not to install an exit list
handler in applications and not to perform a COMMIT. Normally, DB2
installs a process exit list handler in applications and the exit list handler
performs a COMMIT operation if the application ends normally.
For applications that dynamically load the DB2 library and unload it before the application terminates, the invocation of the exit list handler fails because the handler routine is no longer loaded in the application. If your application operates in this way, you should set the DB2NOEXITLIST variable and ensure your application explicitly invokes all required COMMITs. | ||
| DB2NTREMOTEPREG | Windows 95 and Windows NT | Default=null
Value: Any valid Windows 95 or Windows NT machine name | Specifies the remote machine name that contains the Win32 registry list of DB2 instance profiles and DB2 instances. The value for db2remotepreg should only be set once after DB2 is installed, and should not be modified. Use this variable with extreme caution. | ||
| DB2SORCVBUF | Windows 95 and Windows NT | Default=32767 | Specifies the value of TCP/IP receive buffers on Windows 95 and Windows NT operating systems. | ||
| DB2SORT | All, server only | Default=null | Specifies the location of a library to be loaded at runtime by the LOAD utility. The library contains the entry point for functions used in sorting indexing data. Use db2sort to exploit vendor-supplied sorting products for use with the LOAD utility in generating table indexes. The path supplied must be relative to the database server. | ||
| DB2_SORT_AFTER_TQ | All | Default=NO
Values: YES or NO | Specifies how the optimizer works with directed table queues in a
partitioned database when the receiving end requires the data to be sorted,
and the number of receiving nodes is equal to the number of sending
nodes.
When DB2_SORT_AFTER_TQ=N, the optimizer tends to sort at the sending end, and merge the rows at the receiving end. When DB2_SORT_AFTER_TQ=Y, the optimizer tends to transmit the rows unsorted, not merge at the receiving end, and sort the rows at the receiving end after receiving all the rows. | ||
| DB2SYSTEM | Windows NT, Windows 95, OS/2, and UNIX | Default=null | Specifies the name that is used by your users and database administrators
to identify the DB2 server system. If possible, this name should be
unique within your network.
This name is displayed in the system level of the Control Center's object tree to aid administrators in the identification of server systems that can be administered from the Control Center. When using the 'Search the Network' function of the Client Configuration Assistant, DB2 discovery returns this name and it is displayed at the system level in the resulting object tree. This name aids users in identifying the system that contains the database they wish to access. A value for db2system is set at installation time as follows:
| ||
| DB2UPMPR | OS/2 | Default=ON
Values: ON or OFF | Specifies whether or not the UPM logon screen will display on the screen when the user enters the wrong user ID or password on OS/2. | ||